Public issue detail

Runaway CPU investigation for sshd-auth: unknown userspace loop at EVP_DigestUpdate

sshd-auth is stuck in a likely unclassified userspace loop: 100.00% of sampled CPU passed through EVP_DigestUpdate, with repeated restart_syscall x1.

highpackage: openssh-serversource: opensshscore: 106reports: 1successful triage

Last seen: 2026-05-12 08:02 UTC. Public JSON: /v1/issues/019e1aef-da36-7ee2-9139-a41a2bb22bdd

Successful triage

Fixer did not find an honest diff-backed change in this source tree. Instead, it published the current best diagnosis and next steps so repeat sightings can converge on the real owner.

best triagecreated: 2026-05-13 01:54 UTCvalidation: ready

sshd-auth likely remains stuck in an unclassified userspace loop. Fixer produced a diagnosis report and intentionally skipped an automatic package patch attempt because the evidence is not specific enough to choose a safe source change.

Likely owner

external dependency or workload outside the current source tree

Reason: weak-unknown-runaway-evidence

Next steps

Confirm the hotspot still points at external dependency or workload outside the current source tree with a fresh perf sample before filing the bug.
Capture the actual hot backend or child process rather than the parent service wrapper if the issue recurs.
Map external dependency or workload outside the current source tree to its owning package or project and file an upstream or distro bug with the summarized evidence.
If the owner is still unclear, collect another short strace plus `/proc/<pid>/maps` at the moment of the spike.

Browse successful triage

Technical snapshot

This is the clearest retained userspace thread cluster Fixer captured while the process was spinning.

Representative thread backtrace

Command: sshd-auth: unknown [net]
Why Fixer classified it this way: The process is demonstrably CPU-hot, but the current syscall and symbol sample does not point to a single dominant loop family yet.
Wait site: hrtimer_nanosleep
Hot path: EVP_DigestUpdate (100.00% sampled CPU)
Repeated loop: restart_syscall
Top syscalls: restart_syscall x1
Package: openssh-server 1:10.3p1-1
Kernel: 6.17.10+deb14-amd64
Distribution: debian

hrtimer_nanosleep
common_nsleep
__x64_sys_clock_nanosleep
do_syscall_64
entry_SYSCALL_64_after_hwframe

Possible duplicates

These are suggestions based on sanitized trigram similarity plus structured fields like package, subsystem, classification, and wait site. They are not auto-merged.

Runaway CPU investigation for sshd-auth: unknown userspace loop at dequeue_task

possible duplicate

sshd-auth is stuck in a likely unclassified userspace loop: 100.00% of sampled CPU passed through dequeue_task, with repeated restart_syscall x1.

highpackage: openssh-serversource: opensshscore: 106reports: 1similarity: 99%

Why this looks related: same classification, same package, same source package, same subsystem, same target, same wait site, very similar public summary

Last seen: 2026-05-19 03:53 UTC. Public page: /issues/019e3e09-5d4a-7d31-befb-93b419bb1a2e. Public JSON: /v1/issues/019e3e09-5d4a-7d31-befb-93b419bb1a2e

Runaway CPU investigation for sshd-auth: unknown userspace loop at update_cfs_group

possible duplicate

sshd-auth is stuck in a likely unclassified userspace loop: 100.00% of sampled CPU passed through update_cfs_group, with repeated restart_syscall x1.