Runaway CPU investigation for sshd-auth: timer churn at intel_iommu_map_pages

Prompt

## Plan Pass

You are planning a fixer patch before any edits happen.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-vcs-git`. The original pre-edit snapshot is available at `./source` if you need to inspect it. For interpreter processes, plan from the script/application entrypoint evidence first and include the runtime only as a second investigation target unless the evidence proves a runtime bug.

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround. Inspect the relevant code, nearby callers, project contribution docs, and local helper/compat APIs, but do not edit files in this pass.

Return a short markdown plan with these exact sections:

## Problem
## Evidence Confidence
## Proposed Subject
## Patch Plan
## Risks
## Validation

Classify `## Evidence Confidence` as exactly one of `reproduced`, `observed`, or `inferred`. Use `inferred` only for a no-patch diagnosis/report plan unless you can name the extra evidence you will collect before editing; inferred source patches are blocked by Fixer because they are not pull-request-ready. For `observed` source-patch plans, plan to say in the final `## Issue Connection` that the failure was observed by Fixer and not independently reproduced. The plan must explain how the proposed code change addresses the observed issue evidence, call out any prior Fixer patch that should be improved or replaced, reject awkward control flow such as avoidable `goto` if there is a cleaner bounded alternative, name any local helper APIs or maintainer conventions the patch should follow, and keep the intended maintainer-facing explanation clear enough that someone unfamiliar with the local complaint wording can still follow the fix. In `## Validation`, name the reproducible configure/build/test entrypoint you will try from the workspace root before any focused leaf compile or smoke check, and include one bounded independent reproduction attempt for the collected failure signal when it is safe and cheap. Do not plan to claim `reproduced` unless that reproduction command or test can actually show the failure.

## Patch Pass

You are working on a bounded fixer proposal.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-vcs-git`. Produce the smallest reasonable patch for the target repository, keep the change upstreamable, prefer the clearest control flow available, and do not keep avoidable `goto` when a simpler structure would read better. Before introducing new file, process, allocation, locking, networking, or platform APIs, inspect nearby code and project contribution docs for existing helpers or compatibility wrappers and use those local patterns unless you can explain why they do not fit. Validate from a reproducible workspace-root entrypoint before falling back to focused leaf commands; if a build or test cannot run, report the exact command, the exact blocker, and any narrower check you ran instead. During validation, also try one bounded independent reproduction of the collected failure signal when it is safe and cheap, such as a failing test, smoke command, perf/strace comparison, or before/after runtime check. Only use `reproduced` if that command or test actually reproduced the failure; otherwise keep `observed` and report the reproduction blocker. The final explanation must connect the observed issue evidence to the actual code change, not just paraphrase the diff. Write like a maintainer is going to read the patch mail cold: explain the bug in plain language, define subsystem-specific jargon the first time you need it, and make the causal story obvious. Explicitly classify evidence confidence as `reproduced`, `observed`, or `inferred`: `reproduced` means you reproduced the failure locally; `observed` means Fixer has direct crash/log/trace evidence but you did not independently reproduce it; `inferred` means the source patch is not pull-request-ready, so do not leave a source diff unless you first gather stronger observed/reproduced evidence; otherwise return a no-patch diagnosis/report. For any source-changing `observed` patch, say explicitly in `## Issue Connection` that the failure was observed by Fixer and not independently reproduced. If you introduce non-obvious state translation, index remapping, or backend split logic, add a short source comment that explains the invariant being preserved.

Start by explaining the likely root cause from the collected perf, strace, and /proc evidence. If you cannot land a safe patch, leave a diagnosis that is strong enough for an upstream bug report.

A previous Fixer patch attempt already exists for this issue. It was generated by Fixer `0.148.0`. Review that patch before changing code, improve it instead of starting blind, and clean up anything awkward or underexplained. In particular, remove avoidable `goto`, tighten the explanation of what the patch is doing, and make the resulting diff feel ready for upstream git review.
- Prior patch: `./prior-best.patch`
- Prior published session: `./prior-best-session.md`

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround. 

Keep the change narrowly scoped and summarize validation clearly.

In every authoring pass, your final response must start with `Subject: <single-line git commit subject>` and then include these markdown sections exactly:

## Commit Message
A short upstream-friendly explanation of what changed and why. Write it in plain language that a maintainer can follow without local complaint context. If you use subsystem jargon, define it immediately.

## Evidence Confidence
Exactly one word: `reproduced`, `observed`, or `inferred`. Use `reproduced` only when you reproduced the failure locally with a command or test, and include that command/test in `## Validation`. Use `observed` when Fixer has direct crash/log/trace evidence but you did not independently reproduce it. If `## Git Add Paths` lists source files for an `observed` patch, `## Issue Connection` must explicitly say the failure was observed by Fixer and not independently reproduced. Use `inferred` for profiler/strace/indirect evidence; inferred responses may be no-patch diagnoses or reports, but inferred source patches are not pull-request-ready until stronger evidence is gathered.

## Issue Connection
Write this as maintainer-facing patch mail, not as local Fixer notes. Cover four things explicitly in readable sentences: the user-visible symptom or the exact collected signal, the code-level cause or the cautious inference from evidence, the specific change you made, and the expected effect. Do not invent a reproducer, command line, crash, or user-visible failure that is not present in the evidence bundle. If the evidence is direct-but-not-reproduced, say it was observed by Fixer and not independently reproduced. If the evidence is indirect and you did not gather stronger evidence, do not leave a source diff; write a no-patch diagnosis/report instead. Include an explicit effect sentence such as `The expected effect is ...`, `This should reduce ...`, or `This prevents ...` for source patches. If the logic is non-obvious in code, mention that you added a short explanatory comment.

## Git Add Paths
List the repo-relative paths that belong in the final patch, one per line. Use `None` only when you intentionally made no source changes. Include intentionally new files, and do not list generated build artifacts.

## Validation
List the checks you ran, or say clearly that you could not run them. Include the independent reproduction command/test and result when `## Evidence Confidence` is `reproduced`; if reproduction was attempted but blocked, name the exact blocker and keep confidence at `observed` or `inferred`.

Before editing, read the plan at `./plan-output.txt` and follow it unless the code proves part of it wrong. If you change course, say so explicitly in the final write-up instead of silently drifting from the plan.

## Review Pass 1

You are reviewing a freshly generated fixer patch.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-vcs-git`. Review the first patch pass. The original pre-edit snapshot is available at `./source` for diffing. The workspace currently changes these repo-relative paths: auth2.c. Verify that `## Git Add Paths` matches this exact set and that `## Issue Connection` explains every shipped functional file.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround.

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout. The latest author response is at `./patch-output.txt`. Inspect the current code and changed paths like a strict code reviewer. Focus on correctness, regressions, maintainability, awkward control flow such as avoidable `goto`, missing validation, weak or non-gittable commit message text, and explanations that fail to connect the observed issue evidence to the code change. Also review the maintainer experience: the patch mail should be easy to accept upstream, the user-visible bug should be explained in plain language, subsystem-specific jargon should be defined when first used, and any non-obvious state translation or index remapping in code should have a short explanatory comment. Reject patches that omit `## Evidence Confidence`, use anything other than `reproduced`, `observed`, or `inferred`, or sound more certain than that evidence level allows. Reject patches that claim `reproduced` unless `## Validation` names the concrete reproduction command or test and its result. Reject patches that invent a reproducer, command line, crash, or user-visible failure not present in the evidence bundle; indirect profiler or strace evidence may justify a cautious mitigation, but the author must say it is indirect instead of presenting it as a confirmed upstream bug. Reject patches that introduce generic libc/std APIs when nearby code or project docs provide a local compat/helper API for the same job, unless the author explicitly justifies the exception. Reject validation that only reports a leaf object/syntax build when a project-level configure/build/test entrypoint exists and was not attempted; if a full build cannot run, the author must show the exact failed command and blocker.

Do not apply code changes in this pass.

Return a short markdown review report. The first non-empty line must be exactly one of:

RESULT: ok
RESULT: fix-needed

If you choose `RESULT: fix-needed`, add a `## Findings` section with concrete, actionable items.

Response

## Plan Pass

## Problem
Fixer observed `sshd-auth: root [net]` sleeping in a `read, read, clock_nanosleep` sequence with ~1.5-1.8s sleeps. The matching source path is `auth2.c:ensure_minimum_time_since()`, where failed non-`none` userauth attempts use a per-user minimum delay and then double the target delay until it exceeds elapsed backend time.

## Evidence Confidence
observed

## Proposed Subject
`auth2: cap failure-delay catch-up after slow auth attempts`

## Patch Plan
Patch `auth2.c` only. Keep the existing timing-bucket behavior, but cap additional catch-up padding after elapsed auth backend work already exceeds the initial per-user delay. This addresses the observed long post-auth `clock_nanosleep()` signal without fully removing timing equalization.

Use the prior Fixer patch as the starting point, but treat the earlier “return when elapsed exceeds requested delay” approach as rejected because it weakens timing mitigation too much. Prefer the refined bounded cap shape: add a small `MAX_FAIL_DELAY_PAD_SECONDS`, keep straight-line loop logic, avoid `goto`, and add a short comment explaining that failures stay in coarse buckets while slow backend work must not gain large extra sleeps.

Follow OpenSSH conventions found in `README` and nearby code: OpenBSD style, `debug3_f()`/`fatal_f()` naming, `monotime_double()`, `xmalloc()`/`freezero()` where relevant, and the existing portable `nanosleep()` path. I found no higher-level local sleep helper for this exact auth-delay path; `misc.c` has an EINTR retry pattern, but `auth2.c` currently intentionally uses direct `nanosleep()` and the patch should avoid broadening scope.

For an observed source patch, the final `## Issue Connection` must state that Fixer observed the sleep trace and it was not independently reproduced.

## Risks
Authentication timing is security-sensitive. A cap that is too low may reveal timing differences from slow auth backends; a cap that is too high may preserve the observed second-scale sleep problem. The evidence also reports low CPU and kernel `intel_iommu_map_pages`, so the patch must be described as a targeted mitigation for observed auth-delay sleep behavior, not a proven CPU runaway fix.

## Validation
First try the project-level entrypoint from the workspace root:

```sh
./configure && make
```

If it fails due to stale generated files or missing dependencies, report the exact failure and then use the narrowest clean-checkout-reproducible build, likely:

```sh
autoreconf && ./configure && make auth2.o sshd-auth
```

For a bounded independent reproduction attempt, run a temporary local `sshd` under `strace -f -e clock_nanosleep,nanosleep` with a slow failed auth path, such as a delayed `AuthorizedKeysCommand`, and compare whether failed userauth still produces second-scale post-auth sleeps. If sandbox networking blocks this, report that blocker and keep confidence as `observed`.

## Patch Pass

Subject: auth2: cap failure-delay catch-up after slow auth attempts

## Commit Message
The pre-authentication failure delay groups failed authentication attempts into coarse timing buckets. If an authentication backend was already slow, the catch-up loop could still double the target delay until it passed elapsed time, then add a large extra sleep.

Keep the bucketed timing behavior, but cap extra catch-up padding after slow backend work. This preserves the existing timing mitigation while avoiding second-scale sleeps after already slow failed authentication attempts.

## Evidence Confidence
observed

## Issue Connection
Fixer observed `sshd-auth: root [net]` sleeping with a backtrace through `nanosleep()`/`clock_nanosleep()` and strace showing a `read, read, clock_nanosleep` sequence with sleeps around 1.5-1.8 seconds. This failure was observed by Fixer and not independently reproduced.

The cautious code-level connection is `auth2.c`’s pre-authentication failure delay. “Pre-authentication” here means the server-side phase before a login session is accepted. `ensure_minimum_time_since()` already grouped failed auth attempts into timing buckets, but its catch-up loop could add a large delay after backend work had already exceeded the initial 5-9ms per-user delay.

The patch adds a 250ms cap for that extra catch-up padding while keeping the existing bucket loop. The expected effect is to reduce avoidable long post-auth sleeps while retaining coarse timing equalization for failed authentication. I kept the refined prior Fixer approach, avoided new `goto` flow, and added a short comment describing the invariant.

I checked `README`, `README.md`, and the touched auth subsystem. The change follows local OpenSSH conventions and existing helpers: `monotime_double()`, `debug3_f()`, `fatal_f()`, `xmalloc()`, `freezero()`, and the existing direct portable `nanosleep()` use in this helper. No relevant higher-level sleep helper was found, and no new file, process, allocation, locking, networking, or platform APIs were introduced.

## Git Add Paths
auth2.c

## Validation
`./configure && make` from the workspace root failed before compilation with:
`configure: error: ./m4/openssh.m4 newer than configure, run autoreconf`

Focused clean-checkout-style build in a temporary copy passed:
`cp -a . /tmp/openssh-89482-build-$$ && cd /tmp/openssh-89482-build-$$ && autoreconf && ./configure && make auth2.o sshd-auth`

Additional smoke prerequisites built in the same temporary copy:
`make ssh sshd ssh-keygen`

Bounded independent strace smoke was attempted with a temporary local `sshd` and slow `AuthorizedKeysCommand`, but it did not reproduce the collected signal. The attempt was blocked by the temporary uninstalled daemon requiring its privsep setup (`Missing privilege separation directory: /var/empty`) and by sandbox networking (`socket: Operation not permitted` when the client tried `127.0.0.1`).

Patch hygiene passed:
`git diff --check`

## Review Pass 1

RESULT: ok

No blocking issues found. The workspace changes only `auth2.c`, and `## Git Add Paths` matches that exact set. The issue connection explains the shipped file and keeps evidence confidence at `observed` without claiming an independent reproduction.

The patch is narrowly scoped, follows the local `auth2.c` timing-delay style, avoids new platform/process/allocation APIs, and includes a useful comment for the bounded catch-up invariant. Validation attempted the project-level `./configure && make`, reported the generated-file blocker, then used a reproducible temporary `autoreconf && ./configure && make auth2.o sshd-auth` fallback.

Diff

diff --git a/auth2.c b/auth2.c
index 80f766e..334b564 100644
--- a/auth2.c
+++ b/auth2.c
@@ -225,6 +225,7 @@ input_service_request(int type, uint32_t seq, struct ssh *ssh)
 
 #define MIN_FAIL_DELAY_SECONDS 0.005
 #define MAX_FAIL_DELAY_SECONDS 5.0
+#define MAX_FAIL_DELAY_PAD_SECONDS 0.250
 static double
 user_specific_delay(const char *user)
 {
@@ -256,9 +257,18 @@ ensure_minimum_time_since(double start, double seconds)
 		return;
 	}
 
-	/* if we've already passed the requested time, scale up */
-	while ((remain = seconds - elapsed) < 0.0)
+	/*
+	 * Keep failures in coarse timing buckets, but don't let catch-up
+	 * padding after a slow backend add a large extra delay.
+	 */
+	while ((remain = seconds - elapsed) < 0.0) {
 		seconds *= 2;
+		if (seconds - elapsed > MAX_FAIL_DELAY_PAD_SECONDS) {
+			seconds = elapsed + MAX_FAIL_DELAY_PAD_SECONDS;
+			break;
+		}
+	}
+	remain = seconds - elapsed;
 
 	ts.tv_sec = remain;
 	ts.tv_nsec = (remain - ts.tv_sec) * 1000000000;

Prompt

## Plan Pass

You are planning a fixer patch before any edits happen.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-vcs-git`. The original pre-edit snapshot is available at `./source` if you need to inspect it. For interpreter processes, plan from the script/application entrypoint evidence first and include the runtime only as a second investigation target unless the evidence proves a runtime bug.

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround. Inspect the relevant code, nearby callers, project contribution docs, and local helper/compat APIs, but do not edit files in this pass.

Return a short markdown plan with these exact sections:

## Problem
## Evidence Confidence
## Proposed Subject
## Patch Plan
## Risks
## Validation

Classify `## Evidence Confidence` as exactly one of `reproduced`, `observed`, or `inferred`. Use `inferred` only for a no-patch diagnosis/report plan unless you can name the extra evidence you will collect before editing; inferred source patches are blocked by Fixer because they are not pull-request-ready. For `observed` source-patch plans, plan to say in the final `## Issue Connection` that the failure was observed by Fixer and not independently reproduced. The plan must explain how the proposed code change addresses the observed issue evidence, call out any prior Fixer patch that should be improved or replaced, reject awkward control flow such as avoidable `goto` if there is a cleaner bounded alternative, name any local helper APIs or maintainer conventions the patch should follow, and keep the intended maintainer-facing explanation clear enough that someone unfamiliar with the local complaint wording can still follow the fix. In `## Validation`, name the reproducible configure/build/test entrypoint you will try from the workspace root before any focused leaf compile or smoke check, and include one bounded independent reproduction attempt for the collected failure signal when it is safe and cheap. Do not plan to claim `reproduced` unless that reproduction command or test can actually show the failure.

## Patch Pass

You are working on a bounded fixer proposal.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-vcs-git`. Produce the smallest reasonable patch for the target repository, keep the change upstreamable, prefer the clearest control flow available, and do not keep avoidable `goto` when a simpler structure would read better. Before introducing new file, process, allocation, locking, networking, or platform APIs, inspect nearby code and project contribution docs for existing helpers or compatibility wrappers and use those local patterns unless you can explain why they do not fit. Validate from a reproducible workspace-root entrypoint before falling back to focused leaf commands; if a build or test cannot run, report the exact command, the exact blocker, and any narrower check you ran instead. During validation, also try one bounded independent reproduction of the collected failure signal when it is safe and cheap, such as a failing test, smoke command, perf/strace comparison, or before/after runtime check. Only use `reproduced` if that command or test actually reproduced the failure; otherwise keep `observed` and report the reproduction blocker. The final explanation must connect the observed issue evidence to the actual code change, not just paraphrase the diff. Write like a maintainer is going to read the patch mail cold: explain the bug in plain language, define subsystem-specific jargon the first time you need it, and make the causal story obvious. Explicitly classify evidence confidence as `reproduced`, `observed`, or `inferred`: `reproduced` means you reproduced the failure locally; `observed` means Fixer has direct crash/log/trace evidence but you did not independently reproduce it; `inferred` means the source patch is not pull-request-ready, so do not leave a source diff unless you first gather stronger observed/reproduced evidence; otherwise return a no-patch diagnosis/report. For any source-changing `observed` patch, say explicitly in `## Issue Connection` that the failure was observed by Fixer and not independently reproduced. If you introduce non-obvious state translation, index remapping, or backend split logic, add a short source comment that explains the invariant being preserved.

Start by explaining the likely root cause from the collected perf, strace, and /proc evidence. If you cannot land a safe patch, leave a diagnosis that is strong enough for an upstream bug report.

A previous Fixer patch attempt already exists for this issue. It was generated by Fixer `0.148.0`. Review that patch before changing code, improve it instead of starting blind, and clean up anything awkward or underexplained. In particular, remove avoidable `goto`, tighten the explanation of what the patch is doing, and make the resulting diff feel ready for upstream git review.
- Prior patch: `./prior-best.patch`
- Prior published session: `./prior-best-session.md`

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround. 

Keep the change narrowly scoped and summarize validation clearly.

In every authoring pass, your final response must start with `Subject: <single-line git commit subject>` and then include these markdown sections exactly:

## Commit Message
A short upstream-friendly explanation of what changed and why. Write it in plain language that a maintainer can follow without local complaint context. If you use subsystem jargon, define it immediately.

## Evidence Confidence
Exactly one word: `reproduced`, `observed`, or `inferred`. Use `reproduced` only when you reproduced the failure locally with a command or test, and include that command/test in `## Validation`. Use `observed` when Fixer has direct crash/log/trace evidence but you did not independently reproduce it. If `## Git Add Paths` lists source files for an `observed` patch, `## Issue Connection` must explicitly say the failure was observed by Fixer and not independently reproduced. Use `inferred` for profiler/strace/indirect evidence; inferred responses may be no-patch diagnoses or reports, but inferred source patches are not pull-request-ready until stronger evidence is gathered.

## Issue Connection
Write this as maintainer-facing patch mail, not as local Fixer notes. Cover four things explicitly in readable sentences: the user-visible symptom or the exact collected signal, the code-level cause or the cautious inference from evidence, the specific change you made, and the expected effect. Do not invent a reproducer, command line, crash, or user-visible failure that is not present in the evidence bundle. If the evidence is direct-but-not-reproduced, say it was observed by Fixer and not independently reproduced. If the evidence is indirect and you did not gather stronger evidence, do not leave a source diff; write a no-patch diagnosis/report instead. Include an explicit effect sentence such as `The expected effect is ...`, `This should reduce ...`, or `This prevents ...` for source patches. If the logic is non-obvious in code, mention that you added a short explanatory comment.

## Git Add Paths
List the repo-relative paths that belong in the final patch, one per line. Use `None` only when you intentionally made no source changes. Include intentionally new files, and do not list generated build artifacts.

## Validation
List the checks you ran, or say clearly that you could not run them. Include the independent reproduction command/test and result when `## Evidence Confidence` is `reproduced`; if reproduction was attempted but blocked, name the exact blocker and keep confidence at `observed` or `inferred`.

Before editing, read the plan at `./plan-output.txt` and follow it unless the code proves part of it wrong. If you change course, say so explicitly in the final write-up instead of silently drifting from the plan.

## Review Pass 1

You are reviewing a freshly generated fixer patch.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-vcs-git`. Review the first patch pass. The original pre-edit snapshot is available at `./source` for diffing. The workspace currently changes these repo-relative paths: auth2.c. Verify that `## Git Add Paths` matches this exact set and that `## Issue Connection` explains every shipped functional file.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround.

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout. The latest author response is at `./patch-output.txt`. Inspect the current code and changed paths like a strict code reviewer. Focus on correctness, regressions, maintainability, awkward control flow such as avoidable `goto`, missing validation, weak or non-gittable commit message text, and explanations that fail to connect the observed issue evidence to the code change. Also review the maintainer experience: the patch mail should be easy to accept upstream, the user-visible bug should be explained in plain language, subsystem-specific jargon should be defined when first used, and any non-obvious state translation or index remapping in code should have a short explanatory comment. Reject patches that omit `## Evidence Confidence`, use anything other than `reproduced`, `observed`, or `inferred`, or sound more certain than that evidence level allows. Reject patches that claim `reproduced` unless `## Validation` names the concrete reproduction command or test and its result. Reject patches that invent a reproducer, command line, crash, or user-visible failure not present in the evidence bundle; indirect profiler or strace evidence may justify a cautious mitigation, but the author must say it is indirect instead of presenting it as a confirmed upstream bug. Reject patches that introduce generic libc/std APIs when nearby code or project docs provide a local compat/helper API for the same job, unless the author explicitly justifies the exception. Reject validation that only reports a leaf object/syntax build when a project-level configure/build/test entrypoint exists and was not attempted; if a full build cannot run, the author must show the exact failed command and blocker.

Do not apply code changes in this pass.

Return a short markdown review report. The first non-empty line must be exactly one of:

RESULT: ok
RESULT: fix-needed

If you choose `RESULT: fix-needed`, add a `## Findings` section with concrete, actionable items.

Response

## Plan Pass

## Problem
Fixer observed `sshd-auth: root [net]` sleeping in a `read, read, clock_nanosleep` sequence with ~1.5-1.8s sleeps. The matching source path is `auth2.c:ensure_minimum_time_since()`, where failed non-`none` userauth attempts use a per-user minimum delay and then double the target delay until it exceeds elapsed backend time.

## Evidence Confidence
observed

## Proposed Subject
`auth2: cap failure-delay catch-up after slow auth attempts`

## Patch Plan
Patch `auth2.c` only. Keep the existing timing-bucket behavior, but cap additional catch-up padding after elapsed auth backend work already exceeds the initial per-user delay. This addresses the observed long post-auth `clock_nanosleep()` signal without fully removing timing equalization.

Use the prior Fixer patch as the starting point, but treat the earlier “return when elapsed exceeds requested delay” approach as rejected because it weakens timing mitigation too much. Prefer the refined bounded cap shape: add a small `MAX_FAIL_DELAY_PAD_SECONDS`, keep straight-line loop logic, avoid `goto`, and add a short comment explaining that failures stay in coarse buckets while slow backend work must not gain large extra sleeps.

Follow OpenSSH conventions found in `README` and nearby code: OpenBSD style, `debug3_f()`/`fatal_f()` naming, `monotime_double()`, `xmalloc()`/`freezero()` where relevant, and the existing portable `nanosleep()` path. I found no higher-level local sleep helper for this exact auth-delay path; `misc.c` has an EINTR retry pattern, but `auth2.c` currently intentionally uses direct `nanosleep()` and the patch should avoid broadening scope.

For an observed source patch, the final `## Issue Connection` must state that Fixer observed the sleep trace and it was not independently reproduced.

## Risks
Authentication timing is security-sensitive. A cap that is too low may reveal timing differences from slow auth backends; a cap that is too high may preserve the observed second-scale sleep problem. The evidence also reports low CPU and kernel `intel_iommu_map_pages`, so the patch must be described as a targeted mitigation for observed auth-delay sleep behavior, not a proven CPU runaway fix.

## Validation
First try the project-level entrypoint from the workspace root:

```sh
./configure && make
```

If it fails due to stale generated files or missing dependencies, report the exact failure and then use the narrowest clean-checkout-reproducible build, likely:

```sh
autoreconf && ./configure && make auth2.o sshd-auth
```

For a bounded independent reproduction attempt, run a temporary local `sshd` under `strace -f -e clock_nanosleep,nanosleep` with a slow failed auth path, such as a delayed `AuthorizedKeysCommand`, and compare whether failed userauth still produces second-scale post-auth sleeps. If sandbox networking blocks this, report that blocker and keep confidence as `observed`.

## Patch Pass

Subject: auth2: cap failure-delay catch-up after slow auth attempts

## Commit Message
The pre-authentication failure delay groups failed authentication attempts into coarse timing buckets. If an authentication backend was already slow, the catch-up loop could still double the target delay until it passed elapsed time, then add a large extra sleep.

Keep the bucketed timing behavior, but cap extra catch-up padding after slow backend work. This preserves the existing timing mitigation while avoiding second-scale sleeps after already slow failed authentication attempts.

## Evidence Confidence
observed

## Issue Connection
Fixer observed `sshd-auth: root [net]` sleeping with a backtrace through `nanosleep()`/`clock_nanosleep()` and strace showing a `read, read, clock_nanosleep` sequence with sleeps around 1.5-1.8 seconds. This failure was observed by Fixer and not independently reproduced.

The cautious code-level connection is `auth2.c`’s pre-authentication failure delay. “Pre-authentication” here means the server-side phase before a login session is accepted. `ensure_minimum_time_since()` already grouped failed auth attempts into timing buckets, but its catch-up loop could add a large delay after backend work had already exceeded the initial 5-9ms per-user delay.

The patch adds a 250ms cap for that extra catch-up padding while keeping the existing bucket loop. The expected effect is to reduce avoidable long post-auth sleeps while retaining coarse timing equalization for failed authentication. I kept the refined prior Fixer approach, avoided new `goto` flow, and added a short comment describing the invariant.

I checked `README`, `README.md`, and the touched auth subsystem. The change follows local OpenSSH conventions and existing helpers: `monotime_double()`, `debug3_f()`, `fatal_f()`, `xmalloc()`, `freezero()`, and the existing direct portable `nanosleep()` use in this helper. No relevant higher-level sleep helper was found, and no new file, process, allocation, locking, networking, or platform APIs were introduced.

## Git Add Paths
auth2.c

## Validation
`./configure && make` from the workspace root failed before compilation with:
`configure: error: ./m4/openssh.m4 newer than configure, run autoreconf`

Focused clean-checkout-style build in a temporary copy passed:
`cp -a . /tmp/openssh-89482-build-$$ && cd /tmp/openssh-89482-build-$$ && autoreconf && ./configure && make auth2.o sshd-auth`

Additional smoke prerequisites built in the same temporary copy:
`make ssh sshd ssh-keygen`

Bounded independent strace smoke was attempted with a temporary local `sshd` and slow `AuthorizedKeysCommand`, but it did not reproduce the collected signal. The attempt was blocked by the temporary uninstalled daemon requiring its privsep setup (`Missing privilege separation directory: /var/empty`) and by sandbox networking (`socket: Operation not permitted` when the client tried `127.0.0.1`).

Patch hygiene passed:
`git diff --check`

## Review Pass 1

RESULT: ok

No blocking issues found. The workspace changes only `auth2.c`, and `## Git Add Paths` matches that exact set. The issue connection explains the shipped file and keeps evidence confidence at `observed` without claiming an independent reproduction.

The patch is narrowly scoped, follows the local `auth2.c` timing-delay style, avoids new platform/process/allocation APIs, and includes a useful comment for the bounded catch-up invariant. Validation attempted the project-level `./configure && make`, reported the generated-file blocker, then used a reproducible temporary `autoreconf && ./configure && make auth2.o sshd-auth` fallback.

Diff

diff --git a/auth2.c b/auth2.c
index 80f766e..334b564 100644
--- a/auth2.c
+++ b/auth2.c
@@ -225,6 +225,7 @@ input_service_request(int type, uint32_t seq, struct ssh *ssh)
 
 #define MIN_FAIL_DELAY_SECONDS 0.005
 #define MAX_FAIL_DELAY_SECONDS 5.0
+#define MAX_FAIL_DELAY_PAD_SECONDS 0.250
 static double
 user_specific_delay(const char *user)
 {
@@ -256,9 +257,18 @@ ensure_minimum_time_since(double start, double seconds)
 		return;
 	}
 
-	/* if we've already passed the requested time, scale up */
-	while ((remain = seconds - elapsed) < 0.0)
+	/*
+	 * Keep failures in coarse timing buckets, but don't let catch-up
+	 * padding after a slow backend add a large extra delay.
+	 */
+	while ((remain = seconds - elapsed) < 0.0) {
 		seconds *= 2;
+		if (seconds - elapsed > MAX_FAIL_DELAY_PAD_SECONDS) {
+			seconds = elapsed + MAX_FAIL_DELAY_PAD_SECONDS;
+			break;
+		}
+	}
+	remain = seconds - elapsed;
 
 	ts.tv_sec = remain;
 	ts.tv_nsec = (remain - ts.tv_sec) * 1000000000;

Prompt

## Plan Pass

You are planning a fixer patch before any edits happen.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. The original pre-edit snapshot is available at `./source` if you need to inspect it. For interpreter processes, plan from the script/application entrypoint evidence first and include the runtime only as a second investigation target unless the evidence proves a runtime bug.

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround. Inspect the relevant code, nearby callers, project contribution docs, and local helper/compat APIs, but do not edit files in this pass.

Return a short markdown plan with these exact sections:

## Problem
## Evidence Confidence
## Proposed Subject
## Patch Plan
## Risks
## Validation

Classify `## Evidence Confidence` as exactly one of `reproduced`, `observed`, or `inferred`. Use `inferred` only for a no-patch diagnosis/report plan unless you can name the extra evidence you will collect before editing; inferred source patches are blocked by Fixer because they are not pull-request-ready. For `observed` source-patch plans, plan to say in the final `## Issue Connection` that the failure was observed by Fixer and not independently reproduced. The plan must explain how the proposed code change addresses the observed issue evidence, call out any prior Fixer patch that should be improved or replaced, reject awkward control flow such as avoidable `goto` if there is a cleaner bounded alternative, name any local helper APIs or maintainer conventions the patch should follow, and keep the intended maintainer-facing explanation clear enough that someone unfamiliar with the local complaint wording can still follow the fix. In `## Validation`, name the reproducible configure/build/test entrypoint you will try from the workspace root before any focused leaf compile or smoke check, and include one bounded independent reproduction attempt for the collected failure signal when it is safe and cheap. Do not plan to claim `reproduced` unless that reproduction command or test can actually show the failure.

## Patch Pass

You are working on a bounded fixer proposal.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. Produce the smallest reasonable patch for the target repository, keep the change upstreamable, prefer the clearest control flow available, and do not keep avoidable `goto` when a simpler structure would read better. Before introducing new file, process, allocation, locking, networking, or platform APIs, inspect nearby code and project contribution docs for existing helpers or compatibility wrappers and use those local patterns unless you can explain why they do not fit. Validate from a reproducible workspace-root entrypoint before falling back to focused leaf commands; if a build or test cannot run, report the exact command, the exact blocker, and any narrower check you ran instead. During validation, also try one bounded independent reproduction of the collected failure signal when it is safe and cheap, such as a failing test, smoke command, perf/strace comparison, or before/after runtime check. Only use `reproduced` if that command or test actually reproduced the failure; otherwise keep `observed` and report the reproduction blocker. The final explanation must connect the observed issue evidence to the actual code change, not just paraphrase the diff. Write like a maintainer is going to read the patch mail cold: explain the bug in plain language, define subsystem-specific jargon the first time you need it, and make the causal story obvious. Explicitly classify evidence confidence as `reproduced`, `observed`, or `inferred`: `reproduced` means you reproduced the failure locally; `observed` means Fixer has direct crash/log/trace evidence but you did not independently reproduce it; `inferred` means the source patch is not pull-request-ready, so do not leave a source diff unless you first gather stronger observed/reproduced evidence; otherwise return a no-patch diagnosis/report. For any source-changing `observed` patch, say explicitly in `## Issue Connection` that the failure was observed by Fixer and not independently reproduced. If you introduce non-obvious state translation, index remapping, or backend split logic, add a short source comment that explains the invariant being preserved.

Start by explaining the likely root cause from the collected perf, strace, and /proc evidence. If you cannot land a safe patch, leave a diagnosis that is strong enough for an upstream bug report.

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround. 

Keep the change narrowly scoped and summarize validation clearly.

In every authoring pass, your final response must start with `Subject: <single-line git commit subject>` and then include these markdown sections exactly:

## Commit Message
A short upstream-friendly explanation of what changed and why. Write it in plain language that a maintainer can follow without local complaint context. If you use subsystem jargon, define it immediately.

## Evidence Confidence
Exactly one word: `reproduced`, `observed`, or `inferred`. Use `reproduced` only when you reproduced the failure locally with a command or test, and include that command/test in `## Validation`. Use `observed` when Fixer has direct crash/log/trace evidence but you did not independently reproduce it. If `## Git Add Paths` lists source files for an `observed` patch, `## Issue Connection` must explicitly say the failure was observed by Fixer and not independently reproduced. Use `inferred` for profiler/strace/indirect evidence; inferred responses may be no-patch diagnoses or reports, but inferred source patches are not pull-request-ready until stronger evidence is gathered.

## Issue Connection
Write this as maintainer-facing patch mail, not as local Fixer notes. Cover four things explicitly in readable sentences: the user-visible symptom or the exact collected signal, the code-level cause or the cautious inference from evidence, the specific change you made, and the expected effect. Do not invent a reproducer, command line, crash, or user-visible failure that is not present in the evidence bundle. If the evidence is direct-but-not-reproduced, say it was observed by Fixer and not independently reproduced. If the evidence is indirect and you did not gather stronger evidence, do not leave a source diff; write a no-patch diagnosis/report instead. Include an explicit effect sentence such as `The expected effect is ...`, `This should reduce ...`, or `This prevents ...` for source patches. If the logic is non-obvious in code, mention that you added a short explanatory comment.

## Git Add Paths
List the repo-relative paths that belong in the final patch, one per line. Use `None` only when you intentionally made no source changes. Include intentionally new files, and do not list generated build artifacts.

## Validation
List the checks you ran, or say clearly that you could not run them. Include the independent reproduction command/test and result when `## Evidence Confidence` is `reproduced`; if reproduction was attempted but blocked, name the exact blocker and keep confidence at `observed` or `inferred`.

Before editing, read the plan at `./plan-output.txt` and follow it unless the code proves part of it wrong. If you change course, say so explicitly in the final write-up instead of silently drifting from the plan.

## Review Pass 1

You are reviewing a freshly generated fixer patch.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. Review the first patch pass. The original pre-edit snapshot is available at `./source` for diffing. The workspace currently changes these repo-relative paths: auth2.c. Verify that `## Git Add Paths` matches this exact set and that `## Issue Connection` explains every shipped functional file.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround.

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout. The latest author response is at `./patch-output.txt`. Inspect the current code and changed paths like a strict code reviewer. Focus on correctness, regressions, maintainability, awkward control flow such as avoidable `goto`, missing validation, weak or non-gittable commit message text, and explanations that fail to connect the observed issue evidence to the code change. Also review the maintainer experience: the patch mail should be easy to accept upstream, the user-visible bug should be explained in plain language, subsystem-specific jargon should be defined when first used, and any non-obvious state translation or index remapping in code should have a short explanatory comment. Reject patches that omit `## Evidence Confidence`, use anything other than `reproduced`, `observed`, or `inferred`, or sound more certain than that evidence level allows. Reject patches that claim `reproduced` unless `## Validation` names the concrete reproduction command or test and its result. Reject patches that invent a reproducer, command line, crash, or user-visible failure not present in the evidence bundle; indirect profiler or strace evidence may justify a cautious mitigation, but the author must say it is indirect instead of presenting it as a confirmed upstream bug. Reject patches that introduce generic libc/std APIs when nearby code or project docs provide a local compat/helper API for the same job, unless the author explicitly justifies the exception. Reject validation that only reports a leaf object/syntax build when a project-level configure/build/test entrypoint exists and was not attempted; if a full build cannot run, the author must show the exact failed command and blocker.

Do not apply code changes in this pass.

Return a short markdown review report. The first non-empty line must be exactly one of:

RESULT: ok
RESULT: fix-needed

If you choose `RESULT: fix-needed`, add a `## Findings` section with concrete, actionable items.

## Refinement Pass 1

You are refining a fixer patch after an explicit code review.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. Read the latest author response at `./patch-output.txt`. Read the review report at `./review-1-output.txt`. This is refinement round 1. The original pre-edit snapshot is available at `./source` if you need to compare the current patch against it. Re-read the planning pass at `./plan-output.txt` before editing. The workspace currently changes these repo-relative paths: auth2.c. Either keep that exact set synchronized with `## Git Add Paths` and `## Issue Connection`, or revert any unintended file before you answer.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround.

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout. Address the review findings with the smallest reasonable follow-up changes. If the review identifies a runtime or correctness bug in the changed code, you must update the code itself before answering; a metadata-only response is not sufficient. Keep the patch upstream-friendly, use local project helpers and compat APIs when available, avoid awkward control flow when a simpler structure will do, keep the final response gittable, make the maintainer-facing explana

[truncated 6718 bytes]

Response

## Plan Pass

## Problem
Fixer observed `sshd-auth: root [net]` repeatedly reaching `clock_nanosleep()` after reads during pre-auth userauth handling. The embedded strace shows sleeps of about 1.5-1.8s, while the source-level auth failure delay in `auth2.c` is nominally only about 5-9ms. The raw artifact files referenced by `evidence.json` are not present, so this is not independently reproduced yet.

## Evidence Confidence
observed

## Proposed Subject
`sshd-auth: bound failure-delay catch-up after slow auth attempts`

## Patch Plan
Inspect and patch `auth2.c:ensure_minimum_time_since()`, which currently doubles the requested delay until it exceeds elapsed auth processing time, then sleeps the remainder. If a PAM/GSSAPI/other auth method is already slow, this can add a large extra sleep, matching the observed long `clock_nanosleep()` after auth reads.

Replace that exponential catch-up with a bounded, straight-line calculation: compute `remain = seconds - elapsed`; if elapsed already satisfies the requested delay, return; otherwise sleep only the remaining requested delay. Avoid new `goto` control flow.

Follow local OpenSSH conventions: KNF-style C, `debug3_f()`/`fatal_f()` logging style, `monotime_double()`, `xmalloc()`/`freezero()` where already used, and existing portable `nanosleep()` via `openbsd-compat`. No relevant higher-level sleep helper exists; nearby `misc.c` shows EINTR-aware `nanosleep()` retry as a local pattern worth considering if the helper is touched.

No prior Fixer patch was found in the workspace or evidence bundle; this should be an upstream-style source change, not a Debian-only workaround.

## Risks
Authentication timing is security-sensitive. Removing exponential catch-up may reduce timing equalization for very slow auth backends, so the maintainer-facing explanation must be precise: keep the fixed per-user minimum delay, but do not compound already-slow failures into second-scale sleeps.

The evidence names kernel `intel_iommu_map_pages` as the sampled hot path and shows only low CPU usage, so the final patch must not claim a proven CPU runaway fix. It should say Fixer observed the sleep behavior and this is a targeted mitigation for the matching auth-delay path.

## Validation
First try the project-level entrypoint from the workspace root:

```sh
./configure && make
```

If that fails due to missing dependencies or generated files, record the exact failure and then run the narrowest relevant build, likely:

```sh
make auth2.o sshd-auth
```

For a bounded reproduction attempt, run a local debug `sshd` under `strace -f -e clock_nanosleep,nanosleep` with a temporary config that induces a slow failed auth path, then compare pre/post patch sleep duration after the failed userauth request. The expected post-patch signal is no second-scale auth failure sleep added by `ensure_minimum_time_since()`.

## Patch Pass

Subject: sshd-auth: avoid extending delays after slow auth failures

## Commit Message
The pre-auth failure delay pads fast authentication failures up to a small per-user minimum. If an authentication backend had already taken longer than that minimum, `ensure_minimum_time_since()` doubled the target delay until it exceeded the elapsed time, then slept the remainder. That could add a seconds-long sleep after an already slow failed attempt.

Change the helper to return once elapsed time already satisfies the requested minimum delay. This keeps the timing pad for fast failures without compounding slow backend work.

## Evidence Confidence
observed

## Issue Connection
Fixer observed `sshd-auth: root [net]` in a sleeping state with `/proc` showing `wchan` at `unix_stream_read_generic`, a backtrace through `nanosleep()`/`clock_nanosleep()`, and strace showing a `read, read, clock_nanosleep` sequence with sleeps around 1.5-1.8 seconds. This failure was observed by Fixer and not independently reproduced.

The cautious code-level connection is `auth2.c`’s pre-auth failure-delay helper: after an auth request, `ensure_minimum_time_since()` tried to enforce a minimum delay, but if auth processing had already exceeded the requested 5-9ms delay, it scaled the target upward and then slept the difference. That matches the collected long post-auth `clock_nanosleep()` signal.

The patch removes that exponential catch-up and returns when the elapsed auth work already exceeds the requested delay. The expected effect is to preserve the small failure timing pad for fast attempts while preventing slow authentication backends from being followed by an avoidable second-scale sleep. I added a short comment documenting that invariant.

I checked `README.md` and the touched subsystem. The patch follows existing OpenSSH conventions and helpers: `monotime_double()`, `debug3_f()`, and the existing portable `nanosleep()` path; no new platform, process, allocation, or locking APIs were introduced.

## Git Add Paths
auth2.c

## Validation
`./configure && make` from the workspace root failed before build:
`configure: error: ./configure.ac newer than configure, run autoreconf`

Focused build in a temporary copy passed:
`tmpdir=/tmp/openssh-89482-build-$$; cp -a . "$tmpdir"; cd "$tmpdir" && autoreconf && ./configure && make auth2.o sshd-auth`

Additional binaries for the smoke attempt built successfully in the same temporary copy:
`make sshd ssh ssh-keygen`

Bounded independent reproduction attempt was blocked by sandbox networking. I started a temporary `sshd` under `strace` and tried to connect with the built `ssh`, but the client failed with:
`socket: Operation not permitted`
`ssh: connect to host 127.0.0.1 port 40222: failure`

Patch hygiene passed:
`git diff --check`

## Review Pass 1

RESULT: fix-needed

## Findings
- `auth2.c:260`: The patch removes the existing catch-up behavior entirely, which looks like part of the authentication failure timing mitigation. After this change, any failed auth path that takes longer than the 5-9ms per-user delay returns immediately, exposing backend timing differences that the previous code attempted to round up. This is a security-sensitive regression unless the patch replaces it with a bounded alternative that still preserves timing equalization, or gives a much stronger upstream rationale for dropping that protection.

- `auth2.c:819`: The diff still removes an unrelated trailing blank line at EOF. Revert that whitespace-only churn so the patch stays narrowly scoped to the delay logic.

## Refinement Pass 1

Subject: sshd-auth: cap catch-up padding after slow auth failures

## Commit Message
The pre-auth failure delay pads failed authentication attempts into coarse timing buckets, so fast and slow negative results are harder to distinguish. When an authentication backend had already taken longer than the initial per-user delay, the catch-up loop could still add a large extra sleep by doubling the target delay until it passed the elapsed time.

Keep the bucketed catch-up behavior, but cap the extra padding added after an already slow backend. This preserves the timing mitigation while avoiding second-scale additional sleeps after slow failed auth attempts.

## Evidence Confidence
observed

## Issue Connection
Fixer observed `sshd-auth: root [net]` in a sleeping state with a backtrace through `nanosleep()`/`clock_nanosleep()` and strace showing a `read, read, clock_nanosleep` sequence with sleeps around 1.5-1.8 seconds. This failure was observed by Fixer and not independently reproduced.

The cautious code-level connection is `auth2.c`’s pre-auth failure-delay helper. Pre-auth means the server-side authentication phase before a session is accepted. `ensure_minimum_time_since()` groups failed auth attempts into timing buckets, but its catch-up loop could add a large delay after a slow backend had already exceeded the initial 5-9ms per-user delay.

The patch keeps bucketed catch-up padding, caps the extra padding after slow backends at 250ms, and restores the unrelated EOF whitespace noted in review. The expected effect is to reduce avoidable long post-auth sleeps while retaining coarse timing equalization for failed authentication. I added a short comment explaining that invariant.

I checked `README.md` and the touched subsystem. The patch uses existing OpenSSH conventions and helpers: `monotime_double()`, `debug3_f()`, and the portable `nanosleep()` path; no new platform, process, allocation, locking, or networking APIs were introduced.

## Git Add Paths
auth2.c

## Validation
`./configure && make` from the workspace root failed before build:
`configure: error: ./configure.ac newer than configure, run autoreconf`

Focused clean-checkout-style build in a temporary copy passed:
`tmpdir=/tmp/openssh-89482-refine-$$; cp -a . "$tmpdir"; cd "$tmpdir" && autoreconf && ./configure && make auth2.o sshd-auth`

Bounded strace smoke was attempted with a temporary `sshd` and slow `AuthorizedKeysCommand`, but sandbox networking blocked the local client:
`socket: Operation not permitted`
`ssh: connect to host 127.0.0.1 port 40223: failure`

Patch hygiene passed:
`git diff --check`

## Review Pass 2

RESULT: ok

Diff

diff --git a/auth2.c b/auth2.c
index 80f766e..334b564 100644
--- a/auth2.c
+++ b/auth2.c
@@ -225,6 +225,7 @@ input_service_request(int type, uint32_t seq, struct ssh *ssh)
 
 #define MIN_FAIL_DELAY_SECONDS 0.005
 #define MAX_FAIL_DELAY_SECONDS 5.0
+#define MAX_FAIL_DELAY_PAD_SECONDS 0.250
 static double
 user_specific_delay(const char *user)
 {
@@ -256,9 +257,18 @@ ensure_minimum_time_since(double start, double seconds)
 		return;
 	}
 
-	/* if we've already passed the requested time, scale up */
-	while ((remain = seconds - elapsed) < 0.0)
+	/*
+	 * Keep failures in coarse timing buckets, but don't let catch-up
+	 * padding after a slow backend add a large extra delay.
+	 */
+	while ((remain = seconds - elapsed) < 0.0) {
 		seconds *= 2;
+		if (seconds - elapsed > MAX_FAIL_DELAY_PAD_SECONDS) {
+			seconds = elapsed + MAX_FAIL_DELAY_PAD_SECONDS;
+			break;
+		}
+	}
+	remain = seconds - elapsed;
 
 	ts.tv_sec = remain;
 	ts.tv_nsec = (remain - ts.tv_sec) * 1000000000;

Prompt

## Plan Pass

You are planning a fixer patch before any edits happen.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. The original pre-edit snapshot is available at `./source` if you need to inspect it. For interpreter processes, plan from the script/application entrypoint evidence first and include the runtime only as a second investigation target unless the evidence proves a runtime bug.

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround. Inspect the relevant code, nearby callers, project contribution docs, and local helper/compat APIs, but do not edit files in this pass.

Return a short markdown plan with these exact sections:

## Problem
## Evidence Confidence
## Proposed Subject
## Patch Plan
## Risks
## Validation

Classify `## Evidence Confidence` as exactly one of `reproduced`, `observed`, or `inferred`. Use `inferred` only for a no-patch diagnosis/report plan unless you can name the extra evidence you will collect before editing; inferred source patches are blocked by Fixer because they are not pull-request-ready. For `observed` source-patch plans, plan to say in the final `## Issue Connection` that the failure was observed by Fixer and not independently reproduced. The plan must explain how the proposed code change addresses the observed issue evidence, call out any prior Fixer patch that should be improved or replaced, reject awkward control flow such as avoidable `goto` if there is a cleaner bounded alternative, name any local helper APIs or maintainer conventions the patch should follow, and keep the intended maintainer-facing explanation clear enough that someone unfamiliar with the local complaint wording can still follow the fix. In `## Validation`, name the reproducible configure/build/test entrypoint you will try from the workspace root before any focused leaf compile or smoke check, and include one bounded independent reproduction attempt for the collected failure signal when it is safe and cheap. Do not plan to claim `reproduced` unless that reproduction command or test can actually show the failure.

## Patch Pass

You are working on a bounded fixer proposal.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. Produce the smallest reasonable patch for the target repository, keep the change upstreamable, prefer the clearest control flow available, and do not keep avoidable `goto` when a simpler structure would read better. Before introducing new file, process, allocation, locking, networking, or platform APIs, inspect nearby code and project contribution docs for existing helpers or compatibility wrappers and use those local patterns unless you can explain why they do not fit. Validate from a reproducible workspace-root entrypoint before falling back to focused leaf commands; if a build or test cannot run, report the exact command, the exact blocker, and any narrower check you ran instead. During validation, also try one bounded independent reproduction of the collected failure signal when it is safe and cheap, such as a failing test, smoke command, perf/strace comparison, or before/after runtime check. Only use `reproduced` if that command or test actually reproduced the failure; otherwise keep `observed` and report the reproduction blocker. The final explanation must connect the observed issue evidence to the actual code change, not just paraphrase the diff. Write like a maintainer is going to read the patch mail cold: explain the bug in plain language, define subsystem-specific jargon the first time you need it, and make the causal story obvious. Explicitly classify evidence confidence as `reproduced`, `observed`, or `inferred`: `reproduced` means you reproduced the failure locally; `observed` means Fixer has direct crash/log/trace evidence but you did not independently reproduce it; `inferred` means the source patch is not pull-request-ready, so do not leave a source diff unless you first gather stronger observed/reproduced evidence; otherwise return a no-patch diagnosis/report. For any source-changing `observed` patch, say explicitly in `## Issue Connection` that the failure was observed by Fixer and not independently reproduced. If you introduce non-obvious state translation, index remapping, or backend split logic, add a short source comment that explains the invariant being preserved.

Start by explaining the likely root cause from the collected perf, strace, and /proc evidence. If you cannot land a safe patch, leave a diagnosis that is strong enough for an upstream bug report.

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround. 

Keep the change narrowly scoped and summarize validation clearly.

In every authoring pass, your final response must start with `Subject: <single-line git commit subject>` and then include these markdown sections exactly:

## Commit Message
A short upstream-friendly explanation of what changed and why. Write it in plain language that a maintainer can follow without local complaint context. If you use subsystem jargon, define it immediately.

## Evidence Confidence
Exactly one word: `reproduced`, `observed`, or `inferred`. Use `reproduced` only when you reproduced the failure locally with a command or test, and include that command/test in `## Validation`. Use `observed` when Fixer has direct crash/log/trace evidence but you did not independently reproduce it. If `## Git Add Paths` lists source files for an `observed` patch, `## Issue Connection` must explicitly say the failure was observed by Fixer and not independently reproduced. Use `inferred` for profiler/strace/indirect evidence; inferred responses may be no-patch diagnoses or reports, but inferred source patches are not pull-request-ready until stronger evidence is gathered.

## Issue Connection
Write this as maintainer-facing patch mail, not as local Fixer notes. Cover four things explicitly in readable sentences: the user-visible symptom or the exact collected signal, the code-level cause or the cautious inference from evidence, the specific change you made, and the expected effect. Do not invent a reproducer, command line, crash, or user-visible failure that is not present in the evidence bundle. If the evidence is direct-but-not-reproduced, say it was observed by Fixer and not independently reproduced. If the evidence is indirect and you did not gather stronger evidence, do not leave a source diff; write a no-patch diagnosis/report instead. Include an explicit effect sentence such as `The expected effect is ...`, `This should reduce ...`, or `This prevents ...` for source patches. If the logic is non-obvious in code, mention that you added a short explanatory comment.

## Git Add Paths
List the repo-relative paths that belong in the final patch, one per line. Use `None` only when you intentionally made no source changes. Include intentionally new files, and do not list generated build artifacts.

## Validation
List the checks you ran, or say clearly that you could not run them. Include the independent reproduction command/test and result when `## Evidence Confidence` is `reproduced`; if reproduction was attempted but blocked, name the exact blocker and keep confidence at `observed` or `inferred`.

Before editing, read the plan at `./plan-output.txt` and follow it unless the code proves part of it wrong. If you change course, say so explicitly in the final write-up instead of silently drifting from the plan.

## Review Pass 1

You are reviewing a freshly generated fixer patch.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. Review the first patch pass. The original pre-edit snapshot is available at `./source` for diffing. The workspace currently changes these repo-relative paths: auth2.c. Verify that `## Git Add Paths` matches this exact set and that `## Issue Connection` explains every shipped functional file.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround.

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout. The latest author response is at `./patch-output.txt`. Inspect the current code and changed paths like a strict code reviewer. Focus on correctness, regressions, maintainability, awkward control flow such as avoidable `goto`, missing validation, weak or non-gittable commit message text, and explanations that fail to connect the observed issue evidence to the code change. Also review the maintainer experience: the patch mail should be easy to accept upstream, the user-visible bug should be explained in plain language, subsystem-specific jargon should be defined when first used, and any non-obvious state translation or index remapping in code should have a short explanatory comment. Reject patches that omit `## Evidence Confidence`, use anything other than `reproduced`, `observed`, or `inferred`, or sound more certain than that evidence level allows. Reject patches that claim `reproduced` unless `## Validation` names the concrete reproduction command or test and its result. Reject patches that invent a reproducer, command line, crash, or user-visible failure not present in the evidence bundle; indirect profiler or strace evidence may justify a cautious mitigation, but the author must say it is indirect instead of presenting it as a confirmed upstream bug. Reject patches that introduce generic libc/std APIs when nearby code or project docs provide a local compat/helper API for the same job, unless the author explicitly justifies the exception. Reject validation that only reports a leaf object/syntax build when a project-level configure/build/test entrypoint exists and was not attempted; if a full build cannot run, the author must show the exact failed command and blocker.

Do not apply code changes in this pass.

Return a short markdown review report. The first non-empty line must be exactly one of:

RESULT: ok
RESULT: fix-needed

If you choose `RESULT: fix-needed`, add a `## Findings` section with concrete, actionable items.

## Refinement Pass 1

You are refining a fixer patch after an explicit code review.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. Read the latest author response at `./patch-output.txt`. Read the review report at `./review-1-output.txt`. This is refinement round 1. The original pre-edit snapshot is available at `./source` if you need to compare the current patch against it. Re-read the planning pass at `./plan-output.txt` before editing. The workspace currently changes these repo-relative paths: auth2.c. Either keep that exact set synchronized with `## Git Add Paths` and `## Issue Connection`, or revert any unintended file before you answer.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround.

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout. Address the review findings with the smallest reasonable follow-up changes. If the review identifies a runtime or correctness bug in the changed code, you must update the code itself before answering; a metadata-only response is not sufficient. Keep the patch upstream-friendly, use local project helpers and compat APIs when available, avoid awkward control flow when a simpler structure will do, keep the final response gittable, make the maintainer-facing explana

[truncated 6718 bytes]

Response

## Plan Pass

## Problem
Fixer observed `sshd-auth: root [net]` repeatedly reaching `clock_nanosleep()` after reads during pre-auth userauth handling. The embedded strace shows sleeps of about 1.5-1.8s, while the source-level auth failure delay in `auth2.c` is nominally only about 5-9ms. The raw artifact files referenced by `evidence.json` are not present, so this is not independently reproduced yet.

## Evidence Confidence
observed

## Proposed Subject
`sshd-auth: bound failure-delay catch-up after slow auth attempts`

## Patch Plan
Inspect and patch `auth2.c:ensure_minimum_time_since()`, which currently doubles the requested delay until it exceeds elapsed auth processing time, then sleeps the remainder. If a PAM/GSSAPI/other auth method is already slow, this can add a large extra sleep, matching the observed long `clock_nanosleep()` after auth reads.

Replace that exponential catch-up with a bounded, straight-line calculation: compute `remain = seconds - elapsed`; if elapsed already satisfies the requested delay, return; otherwise sleep only the remaining requested delay. Avoid new `goto` control flow.

Follow local OpenSSH conventions: KNF-style C, `debug3_f()`/`fatal_f()` logging style, `monotime_double()`, `xmalloc()`/`freezero()` where already used, and existing portable `nanosleep()` via `openbsd-compat`. No relevant higher-level sleep helper exists; nearby `misc.c` shows EINTR-aware `nanosleep()` retry as a local pattern worth considering if the helper is touched.

No prior Fixer patch was found in the workspace or evidence bundle; this should be an upstream-style source change, not a Debian-only workaround.

## Risks
Authentication timing is security-sensitive. Removing exponential catch-up may reduce timing equalization for very slow auth backends, so the maintainer-facing explanation must be precise: keep the fixed per-user minimum delay, but do not compound already-slow failures into second-scale sleeps.

The evidence names kernel `intel_iommu_map_pages` as the sampled hot path and shows only low CPU usage, so the final patch must not claim a proven CPU runaway fix. It should say Fixer observed the sleep behavior and this is a targeted mitigation for the matching auth-delay path.

## Validation
First try the project-level entrypoint from the workspace root:

```sh
./configure && make
```

If that fails due to missing dependencies or generated files, record the exact failure and then run the narrowest relevant build, likely:

```sh
make auth2.o sshd-auth
```

For a bounded reproduction attempt, run a local debug `sshd` under `strace -f -e clock_nanosleep,nanosleep` with a temporary config that induces a slow failed auth path, then compare pre/post patch sleep duration after the failed userauth request. The expected post-patch signal is no second-scale auth failure sleep added by `ensure_minimum_time_since()`.

## Patch Pass

Subject: sshd-auth: avoid extending delays after slow auth failures

## Commit Message
The pre-auth failure delay pads fast authentication failures up to a small per-user minimum. If an authentication backend had already taken longer than that minimum, `ensure_minimum_time_since()` doubled the target delay until it exceeded the elapsed time, then slept the remainder. That could add a seconds-long sleep after an already slow failed attempt.

Change the helper to return once elapsed time already satisfies the requested minimum delay. This keeps the timing pad for fast failures without compounding slow backend work.

## Evidence Confidence
observed

## Issue Connection
Fixer observed `sshd-auth: root [net]` in a sleeping state with `/proc` showing `wchan` at `unix_stream_read_generic`, a backtrace through `nanosleep()`/`clock_nanosleep()`, and strace showing a `read, read, clock_nanosleep` sequence with sleeps around 1.5-1.8 seconds. This failure was observed by Fixer and not independently reproduced.

The cautious code-level connection is `auth2.c`’s pre-auth failure-delay helper: after an auth request, `ensure_minimum_time_since()` tried to enforce a minimum delay, but if auth processing had already exceeded the requested 5-9ms delay, it scaled the target upward and then slept the difference. That matches the collected long post-auth `clock_nanosleep()` signal.

The patch removes that exponential catch-up and returns when the elapsed auth work already exceeds the requested delay. The expected effect is to preserve the small failure timing pad for fast attempts while preventing slow authentication backends from being followed by an avoidable second-scale sleep. I added a short comment documenting that invariant.

I checked `README.md` and the touched subsystem. The patch follows existing OpenSSH conventions and helpers: `monotime_double()`, `debug3_f()`, and the existing portable `nanosleep()` path; no new platform, process, allocation, or locking APIs were introduced.

## Git Add Paths
auth2.c

## Validation
`./configure && make` from the workspace root failed before build:
`configure: error: ./configure.ac newer than configure, run autoreconf`

Focused build in a temporary copy passed:
`tmpdir=/tmp/openssh-89482-build-$$; cp -a . "$tmpdir"; cd "$tmpdir" && autoreconf && ./configure && make auth2.o sshd-auth`

Additional binaries for the smoke attempt built successfully in the same temporary copy:
`make sshd ssh ssh-keygen`

Bounded independent reproduction attempt was blocked by sandbox networking. I started a temporary `sshd` under `strace` and tried to connect with the built `ssh`, but the client failed with:
`socket: Operation not permitted`
`ssh: connect to host 127.0.0.1 port 40222: failure`

Patch hygiene passed:
`git diff --check`

## Review Pass 1

RESULT: fix-needed

## Findings
- `auth2.c:260`: The patch removes the existing catch-up behavior entirely, which looks like part of the authentication failure timing mitigation. After this change, any failed auth path that takes longer than the 5-9ms per-user delay returns immediately, exposing backend timing differences that the previous code attempted to round up. This is a security-sensitive regression unless the patch replaces it with a bounded alternative that still preserves timing equalization, or gives a much stronger upstream rationale for dropping that protection.

- `auth2.c:819`: The diff still removes an unrelated trailing blank line at EOF. Revert that whitespace-only churn so the patch stays narrowly scoped to the delay logic.

## Refinement Pass 1

Subject: sshd-auth: cap catch-up padding after slow auth failures

## Commit Message
The pre-auth failure delay pads failed authentication attempts into coarse timing buckets, so fast and slow negative results are harder to distinguish. When an authentication backend had already taken longer than the initial per-user delay, the catch-up loop could still add a large extra sleep by doubling the target delay until it passed the elapsed time.

Keep the bucketed catch-up behavior, but cap the extra padding added after an already slow backend. This preserves the timing mitigation while avoiding second-scale additional sleeps after slow failed auth attempts.

## Evidence Confidence
observed

## Issue Connection
Fixer observed `sshd-auth: root [net]` in a sleeping state with a backtrace through `nanosleep()`/`clock_nanosleep()` and strace showing a `read, read, clock_nanosleep` sequence with sleeps around 1.5-1.8 seconds. This failure was observed by Fixer and not independently reproduced.

The cautious code-level connection is `auth2.c`’s pre-auth failure-delay helper. Pre-auth means the server-side authentication phase before a session is accepted. `ensure_minimum_time_since()` groups failed auth attempts into timing buckets, but its catch-up loop could add a large delay after a slow backend had already exceeded the initial 5-9ms per-user delay.

The patch keeps bucketed catch-up padding, caps the extra padding after slow backends at 250ms, and restores the unrelated EOF whitespace noted in review. The expected effect is to reduce avoidable long post-auth sleeps while retaining coarse timing equalization for failed authentication. I added a short comment explaining that invariant.

I checked `README.md` and the touched subsystem. The patch uses existing OpenSSH conventions and helpers: `monotime_double()`, `debug3_f()`, and the portable `nanosleep()` path; no new platform, process, allocation, locking, or networking APIs were introduced.

## Git Add Paths
auth2.c

## Validation
`./configure && make` from the workspace root failed before build:
`configure: error: ./configure.ac newer than configure, run autoreconf`

Focused clean-checkout-style build in a temporary copy passed:
`tmpdir=/tmp/openssh-89482-refine-$$; cp -a . "$tmpdir"; cd "$tmpdir" && autoreconf && ./configure && make auth2.o sshd-auth`

Bounded strace smoke was attempted with a temporary `sshd` and slow `AuthorizedKeysCommand`, but sandbox networking blocked the local client:
`socket: Operation not permitted`
`ssh: connect to host 127.0.0.1 port 40223: failure`

Patch hygiene passed:
`git diff --check`

## Review Pass 2

RESULT: ok

Diff

diff --git a/auth2.c b/auth2.c
index 80f766e..334b564 100644
--- a/auth2.c
+++ b/auth2.c
@@ -225,6 +225,7 @@ input_service_request(int type, uint32_t seq, struct ssh *ssh)
 
 #define MIN_FAIL_DELAY_SECONDS 0.005
 #define MAX_FAIL_DELAY_SECONDS 5.0
+#define MAX_FAIL_DELAY_PAD_SECONDS 0.250
 static double
 user_specific_delay(const char *user)
 {
@@ -256,9 +257,18 @@ ensure_minimum_time_since(double start, double seconds)
 		return;
 	}
 
-	/* if we've already passed the requested time, scale up */
-	while ((remain = seconds - elapsed) < 0.0)
+	/*
+	 * Keep failures in coarse timing buckets, but don't let catch-up
+	 * padding after a slow backend add a large extra delay.
+	 */
+	while ((remain = seconds - elapsed) < 0.0) {
 		seconds *= 2;
+		if (seconds - elapsed > MAX_FAIL_DELAY_PAD_SECONDS) {
+			seconds = elapsed + MAX_FAIL_DELAY_PAD_SECONDS;
+			break;
+		}
+	}
+	remain = seconds - elapsed;
 
 	ts.tv_sec = remain;
 	ts.tv_nsec = (remain - ts.tv_sec) * 1000000000;

Prompt

## Plan Pass

You are planning a fixer patch before any edits happen.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. The original pre-edit snapshot is available at `./source` if you need to inspect it. For interpreter processes, plan from the script/application entrypoint evidence first and include the runtime only as a second investigation target unless the evidence proves a runtime bug.

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround. Inspect the relevant code, nearby callers, project contribution docs, and local helper/compat APIs, but do not edit files in this pass.

Return a short markdown plan with these exact sections:

## Problem
## Evidence Confidence
## Proposed Subject
## Patch Plan
## Risks
## Validation

Classify `## Evidence Confidence` as exactly one of `reproduced`, `observed`, or `inferred`. Use `inferred` only for a no-patch diagnosis/report plan unless you can name the extra evidence you will collect before editing; inferred source patches are blocked by Fixer because they are not pull-request-ready. For `observed` source-patch plans, plan to say in the final `## Issue Connection` that the failure was observed by Fixer and not independently reproduced. The plan must explain how the proposed code change addresses the observed issue evidence, call out any prior Fixer patch that should be improved or replaced, reject awkward control flow such as avoidable `goto` if there is a cleaner bounded alternative, name any local helper APIs or maintainer conventions the patch should follow, and keep the intended maintainer-facing explanation clear enough that someone unfamiliar with the local complaint wording can still follow the fix. In `## Validation`, name the reproducible configure/build/test entrypoint you will try from the workspace root before any focused leaf compile or smoke check, and include one bounded independent reproduction attempt for the collected failure signal when it is safe and cheap. Do not plan to claim `reproduced` unless that reproduction command or test can actually show the failure.

## Patch Pass

You are working on a bounded fixer proposal.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. Produce the smallest reasonable patch for the target repository, keep the change upstreamable, prefer the clearest control flow available, and do not keep avoidable `goto` when a simpler structure would read better. Before introducing new file, process, allocation, locking, networking, or platform APIs, inspect nearby code and project contribution docs for existing helpers or compatibility wrappers and use those local patterns unless you can explain why they do not fit. Validate from a reproducible workspace-root entrypoint before falling back to focused leaf commands; if a build or test cannot run, report the exact command, the exact blocker, and any narrower check you ran instead. During validation, also try one bounded independent reproduction of the collected failure signal when it is safe and cheap, such as a failing test, smoke command, perf/strace comparison, or before/after runtime check. Only use `reproduced` if that command or test actually reproduced the failure; otherwise keep `observed` and report the reproduction blocker. The final explanation must connect the observed issue evidence to the actual code change, not just paraphrase the diff. Write like a maintainer is going to read the patch mail cold: explain the bug in plain language, define subsystem-specific jargon the first time you need it, and make the causal story obvious. Explicitly classify evidence confidence as `reproduced`, `observed`, or `inferred`: `reproduced` means you reproduced the failure locally; `observed` means Fixer has direct crash/log/trace evidence but you did not independently reproduce it; `inferred` means the source patch is not pull-request-ready, so do not leave a source diff unless you first gather stronger observed/reproduced evidence; otherwise return a no-patch diagnosis/report. For any source-changing `observed` patch, say explicitly in `## Issue Connection` that the failure was observed by Fixer and not independently reproduced. If you introduce non-obvious state translation, index remapping, or backend split logic, add a short source comment that explains the invariant being preserved.

Start by explaining the likely root cause from the collected perf, strace, and /proc evidence. If you cannot land a safe patch, leave a diagnosis that is strong enough for an upstream bug report.

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround. 

Keep the change narrowly scoped and summarize validation clearly.

In every authoring pass, your final response must start with `Subject: <single-line git commit subject>` and then include these markdown sections exactly:

## Commit Message
A short upstream-friendly explanation of what changed and why. Write it in plain language that a maintainer can follow without local complaint context. If you use subsystem jargon, define it immediately.

## Evidence Confidence
Exactly one word: `reproduced`, `observed`, or `inferred`. Use `reproduced` only when you reproduced the failure locally with a command or test, and include that command/test in `## Validation`. Use `observed` when Fixer has direct crash/log/trace evidence but you did not independently reproduce it. If `## Git Add Paths` lists source files for an `observed` patch, `## Issue Connection` must explicitly say the failure was observed by Fixer and not independently reproduced. Use `inferred` for profiler/strace/indirect evidence; inferred responses may be no-patch diagnoses or reports, but inferred source patches are not pull-request-ready until stronger evidence is gathered.

## Issue Connection
Write this as maintainer-facing patch mail, not as local Fixer notes. Cover four things explicitly in readable sentences: the user-visible symptom or the exact collected signal, the code-level cause or the cautious inference from evidence, the specific change you made, and the expected effect. Do not invent a reproducer, command line, crash, or user-visible failure that is not present in the evidence bundle. If the evidence is direct-but-not-reproduced, say it was observed by Fixer and not independently reproduced. If the evidence is indirect and you did not gather stronger evidence, do not leave a source diff; write a no-patch diagnosis/report instead. Include an explicit effect sentence such as `The expected effect is ...`, `This should reduce ...`, or `This prevents ...` for source patches. If the logic is non-obvious in code, mention that you added a short explanatory comment.

## Git Add Paths
List the repo-relative paths that belong in the final patch, one per line. Use `None` only when you intentionally made no source changes. Include intentionally new files, and do not list generated build artifacts.

## Validation
List the checks you ran, or say clearly that you could not run them. Include the independent reproduction command/test and result when `## Evidence Confidence` is `reproduced`; if reproduction was attempted but blocked, name the exact blocker and keep confidence at `observed` or `inferred`.

Before editing, read the plan at `./plan-output.txt` and follow it unless the code proves part of it wrong. If you change course, say so explicitly in the final write-up instead of silently drifting from the plan.

## Review Pass 1

You are reviewing a freshly generated fixer patch.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. Review the first patch pass. The original pre-edit snapshot is available at `./source` for diffing.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround.

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout. The latest author response is at `./patch-output.txt`. Inspect the current code and changed paths like a strict code reviewer. Focus on correctness, regressions, maintainability, awkward control flow such as avoidable `goto`, missing validation, weak or non-gittable commit message text, and explanations that fail to connect the observed issue evidence to the code change. Also review the maintainer experience: the patch mail should be easy to accept upstream, the user-visible bug should be explained in plain language, subsystem-specific jargon should be defined when first used, and any non-obvious state translation or index remapping in code should have a short explanatory comment. Reject patches that omit `## Evidence Confidence`, use anything other than `reproduced`, `observed`, or `inferred`, or sound more certain than that evidence level allows. Reject patches that claim `reproduced` unless `## Validation` names the concrete reproduction command or test and its result. Reject patches that invent a reproducer, command line, crash, or user-visible failure not present in the evidence bundle; indirect profiler or strace evidence may justify a cautious mitigation, but the author must say it is indirect instead of presenting it as a confirmed upstream bug. Reject patches that introduce generic libc/std APIs when nearby code or project docs provide a local compat/helper API for the same job, unless the author explicitly justifies the exception. Reject validation that only reports a leaf object/syntax build when a project-level configure/build/test entrypoint exists and was not attempted; if a full build cannot run, the author must show the exact failed command and blocker.

Do not apply code changes in this pass.

Return a short markdown review report. The first non-empty line must be exactly one of:

RESULT: ok
RESULT: fix-needed

If you choose `RESULT: fix-needed`, add a `## Findings` section with concrete, actionable items.

Response

## Plan Pass

## Problem
`sshd-auth` was sampled sleeping around `clock_nanosleep()` after reads during preauth/userauth handling. The source maps this most plausibly to `auth2.c` failure-delay logic, but the evidence also reports only `0.2%` CPU and `S (sleeping)`, so it does not demonstrate a runaway CPU bug.

## Evidence Confidence
inferred

## Proposed Subject
No patch: diagnose `sshd-auth` auth-failure delay evidence before changing upstream OpenSSH timing code

## Patch Plan
Do not edit files from this evidence alone. First collect stronger evidence that `auth2.c:ensure_minimum_time_since()` is causing harmful repeated long sleeps rather than expected failed-auth throttling.

Relevant local conventions/helpers found: `monotime_double()`/`monotime_ts()` from `misc.c`, allocation helpers `xmalloc()` and `freezero()`, digest helper `ssh_digest_memory()`, logging via `debug*_f()`/`fatal_f()`, and monitor IPC through `monitor.c`/`monitor_wrap.c`. `README.md` and `regress/README.regress` identify the upstream build/test flow. No relevant prior Fixer patch was found beyond the baseline commit.

If later evidence confirms a real bug, prefer a small bounded change in `auth2.c` rather than awkward control flow: adjust `ensure_minimum_time_since()` so slow failed-auth attempts do not add multi-second padding unexpectedly, while preserving the minimum-delay intent and OpenSSH style.

## Risks
Authentication timing code is security-sensitive; reducing or reshaping delay may reintroduce username or auth-method timing leaks.

The collected evidence is profiler/strace-only and unsymbolized. It shows sleep and IPC activity, not sustained CPU burn.

Debian carries downstream patches, but this should be treated as an upstream OpenSSH change only if independently justified.

## Validation
Before any focused check, try the project entrypoint from the workspace root: `./configure && make`.

If that fails due to missing dependencies or generated files, record the exact failing command and reason, then run the narrowest reproducible build target such as `make sshd-auth`.

Bounded independent signal check: after building, run a local regression/smoke attempt around failed auth, for example `make tests LTESTS=connect-privsep` and, if safe dependencies are present, trace `sshd-auth` during a failed auth attempt to see whether long `clock_nanosleep` calls are reproducible. Do not claim reproduction unless that trace actually shows the failure signal.

## Patch Pass

Subject: no patch: diagnose sshd-auth sleep evidence

## Commit Message
No source change is included. The collected signal shows `sshd-auth` sleeping in `clock_nanosleep()` after monitor/socket reads, not burning CPU in a tight loop. The likely code path is OpenSSH's failed-authentication timing padding in `auth2.c`, but the evidence is unsymbolized and indirect, so a timing change would be speculative and security-sensitive.

## Evidence Confidence
inferred

## Issue Connection
The collected signal is a Fixer perf/strace/proc snapshot of `/usr/lib/openssh/sshd-auth`: state `S (sleeping)`, total CPU about `0.2%`, repeated `read` calls, and two long `clock_nanosleep()` calls. The cautious code-level inference is that the process is in failed user authentication timing padding, where `auth2.c:ensure_minimum_time_since()` uses OpenSSH helpers like `monotime_double()`, `ssh_digest_memory()`, `xmalloc()`, `freezero()`, and `debug3_f()` around a `nanosleep()` delay.

I did not make a source change. The saved plan said not to patch from this profiler-only evidence alone, and the code review did not prove that plan wrong. A source patch here would risk changing authentication timing behavior without a reproduced or symbolized failure.

The expected effect is no behavioral change: this leaves the tree ready for a stronger upstream report asking for a symbolized `sshd-auth` backtrace or a reproducer that proves the sleep is harmful rather than intended authentication throttling. Relevant style/convention docs checked: `README.md` and `regress/README.regress`; no `CONTRIBUTING`, `HACKING`, `README-hacking`, `docs/`, or `dev-docs/` files were present.

## Git Add Paths
None

## Validation
`./configure && make` failed from the workspace root before build:
`configure: error: ./configure.ac newer than configure, run autoreconf`

Focused fallback `make sshd-auth` also failed because configure had not produced generated files:
`includes.h:19:10: fatal error: config.h: No such file or directory`

Bounded reproduction attempt:
`timeout 5 strace -f -e trace=read,write,nanosleep,clock_nanosleep ./sshd-auth -h`

It did not reproduce the signal. It was blocked because tracing is not permitted in this environment and the workspace binary was not built:
`PTRACE_TRACEME: Operation not permitted`
`Cannot stat './sshd-auth': No such file or directory`

The raw artifact directory named in `evidence.json` was also absent in this container, so I could only use the embedded evidence excerpts.

## Review Pass 1

RESULT: ok

No source changes are present, and the response correctly treats the evidence as `inferred` rather than leaving a speculative OpenSSH timing patch. The author checked the relevant style docs, identified local helpers in the auth timing path, reported the workspace-root build failure with the exact blocker, attempted a focused fallback and bounded reproduction, and did not claim reproduction.

Prompt

## Plan Pass

You are planning a fixer patch before any edits happen.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. The original pre-edit snapshot is available at `./source` if you need to inspect it. For interpreter processes, plan from the script/application entrypoint evidence first and include the runtime only as a second investigation target unless the evidence proves a runtime bug.

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround. Inspect the relevant code, nearby callers, project contribution docs, and local helper/compat APIs, but do not edit files in this pass.

Return a short markdown plan with these exact sections:

## Problem
## Evidence Confidence
## Proposed Subject
## Patch Plan
## Risks
## Validation

Classify `## Evidence Confidence` as exactly one of `reproduced`, `observed`, or `inferred`. Use `inferred` only for a no-patch diagnosis/report plan unless you can name the extra evidence you will collect before editing; inferred source patches are blocked by Fixer because they are not pull-request-ready. For `observed` source-patch plans, plan to say in the final `## Issue Connection` that the failure was observed by Fixer and not independently reproduced. The plan must explain how the proposed code change addresses the observed issue evidence, call out any prior Fixer patch that should be improved or replaced, reject awkward control flow such as avoidable `goto` if there is a cleaner bounded alternative, name any local helper APIs or maintainer conventions the patch should follow, and keep the intended maintainer-facing explanation clear enough that someone unfamiliar with the local complaint wording can still follow the fix. In `## Validation`, name the reproducible configure/build/test entrypoint you will try from the workspace root before any focused leaf compile or smoke check, and include one bounded independent reproduction attempt for the collected failure signal when it is safe and cheap. Do not plan to claim `reproduced` unless that reproduction command or test can actually show the failure.

## Patch Pass

You are working on a bounded fixer proposal.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. Produce the smallest reasonable patch for the target repository, keep the change upstreamable, prefer the clearest control flow available, and do not keep avoidable `goto` when a simpler structure would read better. Before introducing new file, process, allocation, locking, networking, or platform APIs, inspect nearby code and project contribution docs for existing helpers or compatibility wrappers and use those local patterns unless you can explain why they do not fit. Validate from a reproducible workspace-root entrypoint before falling back to focused leaf commands; if a build or test cannot run, report the exact command, the exact blocker, and any narrower check you ran instead. During validation, also try one bounded independent reproduction of the collected failure signal when it is safe and cheap, such as a failing test, smoke command, perf/strace comparison, or before/after runtime check. Only use `reproduced` if that command or test actually reproduced the failure; otherwise keep `observed` and report the reproduction blocker. The final explanation must connect the observed issue evidence to the actual code change, not just paraphrase the diff. Write like a maintainer is going to read the patch mail cold: explain the bug in plain language, define subsystem-specific jargon the first time you need it, and make the causal story obvious. Explicitly classify evidence confidence as `reproduced`, `observed`, or `inferred`: `reproduced` means you reproduced the failure locally; `observed` means Fixer has direct crash/log/trace evidence but you did not independently reproduce it; `inferred` means the source patch is not pull-request-ready, so do not leave a source diff unless you first gather stronger observed/reproduced evidence; otherwise return a no-patch diagnosis/report. For any source-changing `observed` patch, say explicitly in `## Issue Connection` that the failure was observed by Fixer and not independently reproduced. If you introduce non-obvious state translation, index remapping, or backend split logic, add a short source comment that explains the invariant being preserved.

Start by explaining the likely root cause from the collected perf, strace, and /proc evidence. If you cannot land a safe patch, leave a diagnosis that is strong enough for an upstream bug report.

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround. 

Keep the change narrowly scoped and summarize validation clearly.

In every authoring pass, your final response must start with `Subject: <single-line git commit subject>` and then include these markdown sections exactly:

## Commit Message
A short upstream-friendly explanation of what changed and why. Write it in plain language that a maintainer can follow without local complaint context. If you use subsystem jargon, define it immediately.

## Evidence Confidence
Exactly one word: `reproduced`, `observed`, or `inferred`. Use `reproduced` only when you reproduced the failure locally with a command or test, and include that command/test in `## Validation`. Use `observed` when Fixer has direct crash/log/trace evidence but you did not independently reproduce it. If `## Git Add Paths` lists source files for an `observed` patch, `## Issue Connection` must explicitly say the failure was observed by Fixer and not independently reproduced. Use `inferred` for profiler/strace/indirect evidence; inferred responses may be no-patch diagnoses or reports, but inferred source patches are not pull-request-ready until stronger evidence is gathered.

## Issue Connection
Write this as maintainer-facing patch mail, not as local Fixer notes. Cover four things explicitly in readable sentences: the user-visible symptom or the exact collected signal, the code-level cause or the cautious inference from evidence, the specific change you made, and the expected effect. Do not invent a reproducer, command line, crash, or user-visible failure that is not present in the evidence bundle. If the evidence is direct-but-not-reproduced, say it was observed by Fixer and not independently reproduced. If the evidence is indirect and you did not gather stronger evidence, do not leave a source diff; write a no-patch diagnosis/report instead. Include an explicit effect sentence such as `The expected effect is ...`, `This should reduce ...`, or `This prevents ...` for source patches. If the logic is non-obvious in code, mention that you added a short explanatory comment.

## Git Add Paths
List the repo-relative paths that belong in the final patch, one per line. Use `None` only when you intentionally made no source changes. Include intentionally new files, and do not list generated build artifacts.

## Validation
List the checks you ran, or say clearly that you could not run them. Include the independent reproduction command/test and result when `## Evidence Confidence` is `reproduced`; if reproduction was attempted but blocked, name the exact blocker and keep confidence at `observed` or `inferred`.

Before editing, read the plan at `./plan-output.txt` and follow it unless the code proves part of it wrong. If you change course, say so explicitly in the final write-up instead of silently drifting from the plan.

## Review Pass 1

You are reviewing a freshly generated fixer patch.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. Review the first patch pass. The original pre-edit snapshot is available at `./source` for diffing.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround.

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout. The latest author response is at `./patch-output.txt`. Inspect the current code and changed paths like a strict code reviewer. Focus on correctness, regressions, maintainability, awkward control flow such as avoidable `goto`, missing validation, weak or non-gittable commit message text, and explanations that fail to connect the observed issue evidence to the code change. Also review the maintainer experience: the patch mail should be easy to accept upstream, the user-visible bug should be explained in plain language, subsystem-specific jargon should be defined when first used, and any non-obvious state translation or index remapping in code should have a short explanatory comment. Reject patches that omit `## Evidence Confidence`, use anything other than `reproduced`, `observed`, or `inferred`, or sound more certain than that evidence level allows. Reject patches that claim `reproduced` unless `## Validation` names the concrete reproduction command or test and its result. Reject patches that invent a reproducer, command line, crash, or user-visible failure not present in the evidence bundle; indirect profiler or strace evidence may justify a cautious mitigation, but the author must say it is indirect instead of presenting it as a confirmed upstream bug. Reject patches that introduce generic libc/std APIs when nearby code or project docs provide a local compat/helper API for the same job, unless the author explicitly justifies the exception. Reject validation that only reports a leaf object/syntax build when a project-level configure/build/test entrypoint exists and was not attempted; if a full build cannot run, the author must show the exact failed command and blocker.

Do not apply code changes in this pass.

Return a short markdown review report. The first non-empty line must be exactly one of:

RESULT: ok
RESULT: fix-needed

If you choose `RESULT: fix-needed`, add a `## Findings` section with concrete, actionable items.

Response

## Plan Pass

## Problem
`sshd-auth` was sampled sleeping around `clock_nanosleep()` after reads during preauth/userauth handling. The source maps this most plausibly to `auth2.c` failure-delay logic, but the evidence also reports only `0.2%` CPU and `S (sleeping)`, so it does not demonstrate a runaway CPU bug.

## Evidence Confidence
inferred

## Proposed Subject
No patch: diagnose `sshd-auth` auth-failure delay evidence before changing upstream OpenSSH timing code

## Patch Plan
Do not edit files from this evidence alone. First collect stronger evidence that `auth2.c:ensure_minimum_time_since()` is causing harmful repeated long sleeps rather than expected failed-auth throttling.

Relevant local conventions/helpers found: `monotime_double()`/`monotime_ts()` from `misc.c`, allocation helpers `xmalloc()` and `freezero()`, digest helper `ssh_digest_memory()`, logging via `debug*_f()`/`fatal_f()`, and monitor IPC through `monitor.c`/`monitor_wrap.c`. `README.md` and `regress/README.regress` identify the upstream build/test flow. No relevant prior Fixer patch was found beyond the baseline commit.

If later evidence confirms a real bug, prefer a small bounded change in `auth2.c` rather than awkward control flow: adjust `ensure_minimum_time_since()` so slow failed-auth attempts do not add multi-second padding unexpectedly, while preserving the minimum-delay intent and OpenSSH style.

## Risks
Authentication timing code is security-sensitive; reducing or reshaping delay may reintroduce username or auth-method timing leaks.

The collected evidence is profiler/strace-only and unsymbolized. It shows sleep and IPC activity, not sustained CPU burn.

Debian carries downstream patches, but this should be treated as an upstream OpenSSH change only if independently justified.

## Validation
Before any focused check, try the project entrypoint from the workspace root: `./configure && make`.

If that fails due to missing dependencies or generated files, record the exact failing command and reason, then run the narrowest reproducible build target such as `make sshd-auth`.

Bounded independent signal check: after building, run a local regression/smoke attempt around failed auth, for example `make tests LTESTS=connect-privsep` and, if safe dependencies are present, trace `sshd-auth` during a failed auth attempt to see whether long `clock_nanosleep` calls are reproducible. Do not claim reproduction unless that trace actually shows the failure signal.

## Patch Pass

Subject: no patch: diagnose sshd-auth sleep evidence

## Commit Message
No source change is included. The collected signal shows `sshd-auth` sleeping in `clock_nanosleep()` after monitor/socket reads, not burning CPU in a tight loop. The likely code path is OpenSSH's failed-authentication timing padding in `auth2.c`, but the evidence is unsymbolized and indirect, so a timing change would be speculative and security-sensitive.

## Evidence Confidence
inferred

## Issue Connection
The collected signal is a Fixer perf/strace/proc snapshot of `/usr/lib/openssh/sshd-auth`: state `S (sleeping)`, total CPU about `0.2%`, repeated `read` calls, and two long `clock_nanosleep()` calls. The cautious code-level inference is that the process is in failed user authentication timing padding, where `auth2.c:ensure_minimum_time_since()` uses OpenSSH helpers like `monotime_double()`, `ssh_digest_memory()`, `xmalloc()`, `freezero()`, and `debug3_f()` around a `nanosleep()` delay.

I did not make a source change. The saved plan said not to patch from this profiler-only evidence alone, and the code review did not prove that plan wrong. A source patch here would risk changing authentication timing behavior without a reproduced or symbolized failure.

The expected effect is no behavioral change: this leaves the tree ready for a stronger upstream report asking for a symbolized `sshd-auth` backtrace or a reproducer that proves the sleep is harmful rather than intended authentication throttling. Relevant style/convention docs checked: `README.md` and `regress/README.regress`; no `CONTRIBUTING`, `HACKING`, `README-hacking`, `docs/`, or `dev-docs/` files were present.

## Git Add Paths
None

## Validation
`./configure && make` failed from the workspace root before build:
`configure: error: ./configure.ac newer than configure, run autoreconf`

Focused fallback `make sshd-auth` also failed because configure had not produced generated files:
`includes.h:19:10: fatal error: config.h: No such file or directory`

Bounded reproduction attempt:
`timeout 5 strace -f -e trace=read,write,nanosleep,clock_nanosleep ./sshd-auth -h`

It did not reproduce the signal. It was blocked because tracing is not permitted in this environment and the workspace binary was not built:
`PTRACE_TRACEME: Operation not permitted`
`Cannot stat './sshd-auth': No such file or directory`

The raw artifact directory named in `evidence.json` was also absent in this container, so I could only use the embedded evidence excerpts.

## Review Pass 1

RESULT: ok

No source changes are present, and the response correctly treats the evidence as `inferred` rather than leaving a speculative OpenSSH timing patch. The author checked the relevant style docs, identified local helpers in the auth timing path, reported the workspace-root build failure with the exact blocker, attempted a focused fallback and bounded reproduction, and did not claim reproduction.

Prompt

## Plan Pass

You are planning a fixer patch before any edits happen.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. The original pre-edit snapshot is available at `./source` if you need to inspect it. For interpreter processes, plan from the script/application entrypoint evidence first and include the runtime only as a second investigation target unless the evidence proves a runtime bug.

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround. Inspect the relevant code, nearby callers, project contribution docs, and local helper/compat APIs, but do not edit files in this pass.

Return a short markdown plan with these exact sections:

## Problem
## Evidence Confidence
## Proposed Subject
## Patch Plan
## Risks
## Validation

Classify `## Evidence Confidence` as exactly one of `reproduced`, `observed`, or `inferred`. Use `inferred` only for a no-patch diagnosis/report plan unless you can name the extra evidence you will collect before editing; inferred source patches are blocked by Fixer because they are not pull-request-ready. For `observed` source-patch plans, plan to say in the final `## Issue Connection` that the failure was observed by Fixer and not independently reproduced. The plan must explain how the proposed code change addresses the observed issue evidence, call out any prior Fixer patch that should be improved or replaced, reject awkward control flow such as avoidable `goto` if there is a cleaner bounded alternative, name any local helper APIs or maintainer conventions the patch should follow, and keep the intended maintainer-facing explanation clear enough that someone unfamiliar with the local complaint wording can still follow the fix. In `## Validation`, name the reproducible configure/build/test entrypoint you will try from the workspace root before any focused leaf compile or smoke check, and include one bounded independent reproduction attempt for the collected failure signal when it is safe and cheap. Do not plan to claim `reproduced` unless that reproduction command or test can actually show the failure.

## Patch Pass

You are working on a bounded fixer proposal.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. Produce the smallest reasonable patch for the target repository, keep the change upstreamable, prefer the clearest control flow available, and do not keep avoidable `goto` when a simpler structure would read better. Before introducing new file, process, allocation, locking, networking, or platform APIs, inspect nearby code and project contribution docs for existing helpers or compatibility wrappers and use those local patterns unless you can explain why they do not fit. Validate from a reproducible workspace-root entrypoint before falling back to focused leaf commands; if a build or test cannot run, report the exact command, the exact blocker, and any narrower check you ran instead. During validation, also try one bounded independent reproduction of the collected failure signal when it is safe and cheap, such as a failing test, smoke command, perf/strace comparison, or before/after runtime check. Only use `reproduced` if that command or test actually reproduced the failure; otherwise keep `observed` and report the reproduction blocker. The final explanation must connect the observed issue evidence to the actual code change, not just paraphrase the diff. Write like a maintainer is going to read the patch mail cold: explain the bug in plain language, define subsystem-specific jargon the first time you need it, and make the causal story obvious. Explicitly classify evidence confidence as `reproduced`, `observed`, or `inferred`: `reproduced` means you reproduced the failure locally; `observed` means Fixer has direct crash/log/trace evidence but you did not independently reproduce it; `inferred` means the source patch is not pull-request-ready, so do not leave a source diff unless you first gather stronger observed/reproduced evidence; otherwise return a no-patch diagnosis/report. For any source-changing `observed` patch, say explicitly in `## Issue Connection` that the failure was observed by Fixer and not independently reproduced. If you introduce non-obvious state translation, index remapping, or backend split logic, add a short source comment that explains the invariant being preserved.

Start by explaining the likely root cause from the collected perf, strace, and /proc evidence. If you cannot land a safe patch, leave a diagnosis that is strong enough for an upstream bug report.

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround. 

Keep the change narrowly scoped and summarize validation clearly.

In every authoring pass, your final response must start with `Subject: <single-line git commit subject>` and then include these markdown sections exactly:

## Commit Message
A short upstream-friendly explanation of what changed and why. Write it in plain language that a maintainer can follow without local complaint context. If you use subsystem jargon, define it immediately.

## Evidence Confidence
Exactly one word: `reproduced`, `observed`, or `inferred`. Use `reproduced` only when you reproduced the failure locally with a command or test, and include that command/test in `## Validation`. Use `observed` when Fixer has direct crash/log/trace evidence but you did not independently reproduce it. If `## Git Add Paths` lists source files for an `observed` patch, `## Issue Connection` must explicitly say the failure was observed by Fixer and not independently reproduced. Use `inferred` for profiler/strace/indirect evidence; inferred responses may be no-patch diagnoses or reports, but inferred source patches are not pull-request-ready until stronger evidence is gathered.

## Issue Connection
Write this as maintainer-facing patch mail, not as local Fixer notes. Cover four things explicitly in readable sentences: the user-visible symptom or the exact collected signal, the code-level cause or the cautious inference from evidence, the specific change you made, and the expected effect. Do not invent a reproducer, command line, crash, or user-visible failure that is not present in the evidence bundle. If the evidence is direct-but-not-reproduced, say it was observed by Fixer and not independently reproduced. If the evidence is indirect and you did not gather stronger evidence, do not leave a source diff; write a no-patch diagnosis/report instead. Include an explicit effect sentence such as `The expected effect is ...`, `This should reduce ...`, or `This prevents ...` for source patches. If the logic is non-obvious in code, mention that you added a short explanatory comment.

## Git Add Paths
List the repo-relative paths that belong in the final patch, one per line. Use `None` only when you intentionally made no source changes. Include intentionally new files, and do not list generated build artifacts.

## Validation
List the checks you ran, or say clearly that you could not run them. Include the independent reproduction command/test and result when `## Evidence Confidence` is `reproduced`; if reproduction was attempted but blocked, name the exact blocker and keep confidence at `observed` or `inferred`.

Before editing, read the plan at `./plan-output.txt` and follow it unless the code proves part of it wrong. If you change course, say so explicitly in the final write-up instead of silently drifting from the plan.

## Review Pass 1

You are reviewing a freshly generated fixer patch.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. Review the first patch pass. The original pre-edit snapshot is available at `./source` for diffing.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround.

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout. The latest author response is at `./patch-output.txt`. Inspect the current code and changed paths like a strict code reviewer. Focus on correctness, regressions, maintainability, awkward control flow such as avoidable `goto`, missing validation, weak or non-gittable commit message text, and explanations that fail to connect the observed issue evidence to the code change. Also review the maintainer experience: the patch mail should be easy to accept upstream, the user-visible bug should be explained in plain language, subsystem-specific jargon should be defined when first used, and any non-obvious state translation or index remapping in code should have a short explanatory comment. Reject patches that omit `## Evidence Confidence`, use anything other than `reproduced`, `observed`, or `inferred`, or sound more certain than that evidence level allows. Reject patches that claim `reproduced` unless `## Validation` names the concrete reproduction command or test and its result. Reject patches that invent a reproducer, command line, crash, or user-visible failure not present in the evidence bundle; indirect profiler or strace evidence may justify a cautious mitigation, but the author must say it is indirect instead of presenting it as a confirmed upstream bug. Reject patches that introduce generic libc/std APIs when nearby code or project docs provide a local compat/helper API for the same job, unless the author explicitly justifies the exception. Reject validation that only reports a leaf object/syntax build when a project-level configure/build/test entrypoint exists and was not attempted; if a full build cannot run, the author must show the exact failed command and blocker.

Do not apply code changes in this pass.

Return a short markdown review report. The first non-empty line must be exactly one of:

RESULT: ok
RESULT: fix-needed

If you choose `RESULT: fix-needed`, add a `## Findings` section with concrete, actionable items.

Response

## Plan Pass

## Problem

Fixer reported `sshd-auth` as a likely timer-churn runaway, but the embedded evidence does not show a confirmed OpenSSH defect: the process was sleeping, total CPU was 0.2%, `wchan` was `unix_stream_read_generic`, and the strace excerpt shows blocking `read()` calls plus `clock_nanosleep()` after authentication traffic. Source inspection maps the sleep to `auth2.c`’s intentional authentication-failure timing mitigation in `ensure_minimum_time_since()`.

## Evidence Confidence

inferred

## Proposed Subject

No source patch: `sshd-auth` sampled in expected authentication-failure delay, not a reproduced runaway.

## Patch Plan

Do not edit files in this pass. Treat this as a no-patch diagnosis unless additional evidence shows excessive or repeated failure-delay sleeps outside normal authentication handling.

Relevant conventions/helpers found: `auth2.c` uses `monotime_double()`, `xmalloc()`, `freezero()`, `fatal_f()`, and existing OpenSSH cleanup style; monitor IPC uses `sshbuf` and `mm_request_*`; monitor log reads use `atomicio()`. `README.md` documents the upstream portable build flow; no `CONTRIBUTING`, `HACKING`, `README-hacking`, `docs/`, or `dev-docs/` were found.

No prior Fixer patch is present for this proposal, and there is no `prior-best.patch` to improve or replace. If later evidence justifies a source change, avoid adding awkward control flow such as a new avoidable `goto`; keep any change bounded in `auth2.c` and preserve the timing-channel mitigation.

## Risks

Changing or removing this sleep would risk reintroducing user-enumeration/timing side channels. The current evidence is profiler-only/indirect and includes a kernel hot symbol, not a source-level OpenSSH hot loop. The raw investigation files referenced by `evidence.json` were not available at those paths, so the excerpts could not be independently rechecked.

## Validation

For any future edit, first run the project entrypoint from the workspace root:

`./configure && make`

If that fails due missing dependencies/generated files, record the exact failure, then run the narrowest reproducible build such as `make sshd-auth` or `make auth2.o`.

Bounded independent reproduction attempt before any patch: run a local test `sshd`/`ssh` authentication failure under `strace -f -e read,write,clock_nanosleep` and confirm whether the observed `clock_nanosleep()` corresponds to `auth2.c`’s expected failure delay rather than unbounded timer churn.

## Patch Pass

Subject: No patch: diagnose sshd-auth timer sample as auth delay

## Commit Message
No source change is included. The collected signal points at an intentional `sshd-auth` authentication-failure delay, not a confirmed OpenSSH runaway loop. Editing that path without stronger evidence would risk weakening timing-channel protections.

## Evidence Confidence
inferred

## Issue Connection
Fixer sampled an `sshd-auth: root [net]` process and classified it as timer churn because the backtrace included `clock_nanosleep()`/`nanosleep()` and the strace excerpt showed `read`, `read`, then `clock_nanosleep`. The same evidence also showed the process in `S (sleeping)`, only 0.2% CPU, `wchan` as `unix_stream_read_generic`, and blocking reads on the monitor socket.

The cautious source-level inference is that the sleep corresponds to `auth2.c`’s `ensure_minimum_time_since()` call after failed non-`none` authentication requests. That function is part of OpenSSH’s timing mitigation for authentication failures. Nearby code uses existing OpenSSH conventions and helpers such as `monotime_double()`, `xmalloc()`, `freezero()`, `fatal_f()`, `sshbuf`, `mm_request_*`, and `atomicio()`; no replacement helper was needed because no source change is safe here.

I made no code change. This follows the saved plan in `plan-output.txt`; the code did not prove the plan wrong. The expected effect is to avoid landing an inferred, non-pull-request-ready patch that could remove or distort an intentional authentication delay.

## Git Add Paths
None

## Validation
Checked upstream/project guidance: only `README.md` was present among `CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, and `dev-docs/`. It documents the portable OpenSSH `./configure && make` flow.

Ran project entrypoint from the workspace root:

`./configure && make`

Result: failed during configure with:

`configure: error: ./configure.ac newer than configure, run autoreconf`

Focused check attempted:

`make auth2.o`

Result: failed because generated configuration was absent:

`includes.h:19:10: fatal error: config.h: No such file or directory`

Independent reproduction attempt: tried to run a local auth-failure smoke test using installed `/usr/sbin/sshd`, `/usr/bin/ssh`, and `strace -ff -e read,write,clock_nanosleep,nanosleep`. It was blocked by sandbox permissions: `strace` failed with `PTRACE_TRACEME: Operation not permitted` / `ptrace(PTRACE_SEIZE, 8): Operation not permitted`, and the SSH client failed with `socket: Operation not permitted`.

Final tree check: `git status --short` is clean.

## Review Pass 1

RESULT: ok

No findings. The pass correctly leaves no source diff for indirect profiler/strace evidence, uses `inferred` confidence, avoids claiming a reproduced bug, names the relevant OpenSSH helper/convention context, and reports both the project-level validation blocker and the blocked independent reproduction attempt. The worktree is clean.

Prompt

## Plan Pass

You are planning a fixer patch before any edits happen.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. The original pre-edit snapshot is available at `./source` if you need to inspect it. For interpreter processes, plan from the script/application entrypoint evidence first and include the runtime only as a second investigation target unless the evidence proves a runtime bug.

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround. Inspect the relevant code, nearby callers, project contribution docs, and local helper/compat APIs, but do not edit files in this pass.

Return a short markdown plan with these exact sections:

## Problem
## Evidence Confidence
## Proposed Subject
## Patch Plan
## Risks
## Validation

Classify `## Evidence Confidence` as exactly one of `reproduced`, `observed`, or `inferred`. Use `inferred` only for a no-patch diagnosis/report plan unless you can name the extra evidence you will collect before editing; inferred source patches are blocked by Fixer because they are not pull-request-ready. For `observed` source-patch plans, plan to say in the final `## Issue Connection` that the failure was observed by Fixer and not independently reproduced. The plan must explain how the proposed code change addresses the observed issue evidence, call out any prior Fixer patch that should be improved or replaced, reject awkward control flow such as avoidable `goto` if there is a cleaner bounded alternative, name any local helper APIs or maintainer conventions the patch should follow, and keep the intended maintainer-facing explanation clear enough that someone unfamiliar with the local complaint wording can still follow the fix. In `## Validation`, name the reproducible configure/build/test entrypoint you will try from the workspace root before any focused leaf compile or smoke check, and include one bounded independent reproduction attempt for the collected failure signal when it is safe and cheap. Do not plan to claim `reproduced` unless that reproduction command or test can actually show the failure.

## Patch Pass

You are working on a bounded fixer proposal.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. Produce the smallest reasonable patch for the target repository, keep the change upstreamable, prefer the clearest control flow available, and do not keep avoidable `goto` when a simpler structure would read better. Before introducing new file, process, allocation, locking, networking, or platform APIs, inspect nearby code and project contribution docs for existing helpers or compatibility wrappers and use those local patterns unless you can explain why they do not fit. Validate from a reproducible workspace-root entrypoint before falling back to focused leaf commands; if a build or test cannot run, report the exact command, the exact blocker, and any narrower check you ran instead. During validation, also try one bounded independent reproduction of the collected failure signal when it is safe and cheap, such as a failing test, smoke command, perf/strace comparison, or before/after runtime check. Only use `reproduced` if that command or test actually reproduced the failure; otherwise keep `observed` and report the reproduction blocker. The final explanation must connect the observed issue evidence to the actual code change, not just paraphrase the diff. Write like a maintainer is going to read the patch mail cold: explain the bug in plain language, define subsystem-specific jargon the first time you need it, and make the causal story obvious. Explicitly classify evidence confidence as `reproduced`, `observed`, or `inferred`: `reproduced` means you reproduced the failure locally; `observed` means Fixer has direct crash/log/trace evidence but you did not independently reproduce it; `inferred` means the source patch is not pull-request-ready, so do not leave a source diff unless you first gather stronger observed/reproduced evidence; otherwise return a no-patch diagnosis/report. For any source-changing `observed` patch, say explicitly in `## Issue Connection` that the failure was observed by Fixer and not independently reproduced. If you introduce non-obvious state translation, index remapping, or backend split logic, add a short source comment that explains the invariant being preserved.

Start by explaining the likely root cause from the collected perf, strace, and /proc evidence. If you cannot land a safe patch, leave a diagnosis that is strong enough for an upstream bug report.

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround. 

Keep the change narrowly scoped and summarize validation clearly.

In every authoring pass, your final response must start with `Subject: <single-line git commit subject>` and then include these markdown sections exactly:

## Commit Message
A short upstream-friendly explanation of what changed and why. Write it in plain language that a maintainer can follow without local complaint context. If you use subsystem jargon, define it immediately.

## Evidence Confidence
Exactly one word: `reproduced`, `observed`, or `inferred`. Use `reproduced` only when you reproduced the failure locally with a command or test, and include that command/test in `## Validation`. Use `observed` when Fixer has direct crash/log/trace evidence but you did not independently reproduce it. If `## Git Add Paths` lists source files for an `observed` patch, `## Issue Connection` must explicitly say the failure was observed by Fixer and not independently reproduced. Use `inferred` for profiler/strace/indirect evidence; inferred responses may be no-patch diagnoses or reports, but inferred source patches are not pull-request-ready until stronger evidence is gathered.

## Issue Connection
Write this as maintainer-facing patch mail, not as local Fixer notes. Cover four things explicitly in readable sentences: the user-visible symptom or the exact collected signal, the code-level cause or the cautious inference from evidence, the specific change you made, and the expected effect. Do not invent a reproducer, command line, crash, or user-visible failure that is not present in the evidence bundle. If the evidence is direct-but-not-reproduced, say it was observed by Fixer and not independently reproduced. If the evidence is indirect and you did not gather stronger evidence, do not leave a source diff; write a no-patch diagnosis/report instead. Include an explicit effect sentence such as `The expected effect is ...`, `This should reduce ...`, or `This prevents ...` for source patches. If the logic is non-obvious in code, mention that you added a short explanatory comment.

## Git Add Paths
List the repo-relative paths that belong in the final patch, one per line. Use `None` only when you intentionally made no source changes. Include intentionally new files, and do not list generated build artifacts.

## Validation
List the checks you ran, or say clearly that you could not run them. Include the independent reproduction command/test and result when `## Evidence Confidence` is `reproduced`; if reproduction was attempted but blocked, name the exact blocker and keep confidence at `observed` or `inferred`.

Before editing, read the plan at `./plan-output.txt` and follow it unless the code proves part of it wrong. If you change course, say so explicitly in the final write-up instead of silently drifting from the plan.

## Review Pass 1

You are reviewing a freshly generated fixer patch.

Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. Review the first patch pass. The original pre-edit snapshot is available at `./source` for diffing.

Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `openssh` upstream patch, not just a Debian-local workaround.

Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout. The latest author response is at `./patch-output.txt`. Inspect the current code and changed paths like a strict code reviewer. Focus on correctness, regressions, maintainability, awkward control flow such as avoidable `goto`, missing validation, weak or non-gittable commit message text, and explanations that fail to connect the observed issue evidence to the code change. Also review the maintainer experience: the patch mail should be easy to accept upstream, the user-visible bug should be explained in plain language, subsystem-specific jargon should be defined when first used, and any non-obvious state translation or index remapping in code should have a short explanatory comment. Reject patches that omit `## Evidence Confidence`, use anything other than `reproduced`, `observed`, or `inferred`, or sound more certain than that evidence level allows. Reject patches that claim `reproduced` unless `## Validation` names the concrete reproduction command or test and its result. Reject patches that invent a reproducer, command line, crash, or user-visible failure not present in the evidence bundle; indirect profiler or strace evidence may justify a cautious mitigation, but the author must say it is indirect instead of presenting it as a confirmed upstream bug. Reject patches that introduce generic libc/std APIs when nearby code or project docs provide a local compat/helper API for the same job, unless the author explicitly justifies the exception. Reject validation that only reports a leaf object/syntax build when a project-level configure/build/test entrypoint exists and was not attempted; if a full build cannot run, the author must show the exact failed command and blocker.

Do not apply code changes in this pass.

Return a short markdown review report. The first non-empty line must be exactly one of:

RESULT: ok
RESULT: fix-needed

If you choose `RESULT: fix-needed`, add a `## Findings` section with concrete, actionable items.

Response

## Plan Pass

## Problem

Fixer reported `sshd-auth` as a likely timer-churn runaway, but the embedded evidence does not show a confirmed OpenSSH defect: the process was sleeping, total CPU was 0.2%, `wchan` was `unix_stream_read_generic`, and the strace excerpt shows blocking `read()` calls plus `clock_nanosleep()` after authentication traffic. Source inspection maps the sleep to `auth2.c`’s intentional authentication-failure timing mitigation in `ensure_minimum_time_since()`.

## Evidence Confidence

inferred

## Proposed Subject

No source patch: `sshd-auth` sampled in expected authentication-failure delay, not a reproduced runaway.

## Patch Plan

Do not edit files in this pass. Treat this as a no-patch diagnosis unless additional evidence shows excessive or repeated failure-delay sleeps outside normal authentication handling.

Relevant conventions/helpers found: `auth2.c` uses `monotime_double()`, `xmalloc()`, `freezero()`, `fatal_f()`, and existing OpenSSH cleanup style; monitor IPC uses `sshbuf` and `mm_request_*`; monitor log reads use `atomicio()`. `README.md` documents the upstream portable build flow; no `CONTRIBUTING`, `HACKING`, `README-hacking`, `docs/`, or `dev-docs/` were found.

No prior Fixer patch is present for this proposal, and there is no `prior-best.patch` to improve or replace. If later evidence justifies a source change, avoid adding awkward control flow such as a new avoidable `goto`; keep any change bounded in `auth2.c` and preserve the timing-channel mitigation.

## Risks

Changing or removing this sleep would risk reintroducing user-enumeration/timing side channels. The current evidence is profiler-only/indirect and includes a kernel hot symbol, not a source-level OpenSSH hot loop. The raw investigation files referenced by `evidence.json` were not available at those paths, so the excerpts could not be independently rechecked.

## Validation

For any future edit, first run the project entrypoint from the workspace root:

`./configure && make`

If that fails due missing dependencies/generated files, record the exact failure, then run the narrowest reproducible build such as `make sshd-auth` or `make auth2.o`.

Bounded independent reproduction attempt before any patch: run a local test `sshd`/`ssh` authentication failure under `strace -f -e read,write,clock_nanosleep` and confirm whether the observed `clock_nanosleep()` corresponds to `auth2.c`’s expected failure delay rather than unbounded timer churn.

## Patch Pass

Subject: No patch: diagnose sshd-auth timer sample as auth delay

## Commit Message
No source change is included. The collected signal points at an intentional `sshd-auth` authentication-failure delay, not a confirmed OpenSSH runaway loop. Editing that path without stronger evidence would risk weakening timing-channel protections.

## Evidence Confidence
inferred

## Issue Connection
Fixer sampled an `sshd-auth: root [net]` process and classified it as timer churn because the backtrace included `clock_nanosleep()`/`nanosleep()` and the strace excerpt showed `read`, `read`, then `clock_nanosleep`. The same evidence also showed the process in `S (sleeping)`, only 0.2% CPU, `wchan` as `unix_stream_read_generic`, and blocking reads on the monitor socket.

The cautious source-level inference is that the sleep corresponds to `auth2.c`’s `ensure_minimum_time_since()` call after failed non-`none` authentication requests. That function is part of OpenSSH’s timing mitigation for authentication failures. Nearby code uses existing OpenSSH conventions and helpers such as `monotime_double()`, `xmalloc()`, `freezero()`, `fatal_f()`, `sshbuf`, `mm_request_*`, and `atomicio()`; no replacement helper was needed because no source change is safe here.

I made no code change. This follows the saved plan in `plan-output.txt`; the code did not prove the plan wrong. The expected effect is to avoid landing an inferred, non-pull-request-ready patch that could remove or distort an intentional authentication delay.

## Git Add Paths
None

## Validation
Checked upstream/project guidance: only `README.md` was present among `CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, and `dev-docs/`. It documents the portable OpenSSH `./configure && make` flow.

Ran project entrypoint from the workspace root:

`./configure && make`

Result: failed during configure with:

`configure: error: ./configure.ac newer than configure, run autoreconf`

Focused check attempted:

`make auth2.o`

Result: failed because generated configuration was absent:

`includes.h:19:10: fatal error: config.h: No such file or directory`

Independent reproduction attempt: tried to run a local auth-failure smoke test using installed `/usr/sbin/sshd`, `/usr/bin/ssh`, and `strace -ff -e read,write,clock_nanosleep,nanosleep`. It was blocked by sandbox permissions: `strace` failed with `PTRACE_TRACEME: Operation not permitted` / `ptrace(PTRACE_SEIZE, 8): Operation not permitted`, and the SSH client failed with `socket: Operation not permitted`.

Final tree check: `git status --short` is clean.

## Review Pass 1

RESULT: ok

No findings. The pass correctly leaves no source diff for indirect profiler/strace evidence, uses `inferred` confidence, avoids claiming a reproduced bug, names the relevant OpenSSH helper/convention context, and reports both the project-level validation blocker and the blocked independent reproduction attempt. The worktree is clean.