CVE-2025-40327 - Linux Kernel perf async-profiler CPU Clock Hang Vulnerability

CVE-2025-40327 - Linux Kernel perf async-profiler CPU Clock Hang Vulnerability

https://cvefeed.io/rssfeed/latest.atom / Tue, 12/09/2025 - 10:52
CVE ID : CVE-2025-40327
Published : Dec. 9, 2025, 6:28 a.m. | 1 hour, 46 minutes ago
Description : In the Linux kernel, the following vulnerability has been resolved: perf/core: Fix system hang caused by cpu-clock usage cpu-clock usage by the async-profiler tool can trigger a system hang, which got bisected back to the following commit by Octavia Togami: 18dbcbfabfff ("perf: Fix the POLL_HUP delivery breakage") causes this issue The root cause of the hang is that cpu-clock is a special type of SW event which relies on hrtimers. The __perf_event_overflow() callback is invoked from the hrtimer handler for cpu-clock events, and __perf_event_overflow() tries to call cpu_clock_event_stop() to stop the event, which calls htimer_cancel() to cancel the hrtimer. But that's a recursion into the hrtimer code from a hrtimer handler, which (unsurprisingly) deadlocks. To fix this bug, use hrtimer_try_to_cancel() instead, and set the PERF_HES_STOPPED flag, which causes perf_swevent_hrtimer() to stop the event once it sees the PERF_HES_STOPPED flag. [ mingo: Fixed the comments and improved the changelog. ]
Severity: 0.0 | NA
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