System Hang Vulnerability in Linux Kernel: Affected by Async-Profiler Tool

CVE-2025-40327

What is CVE-2025-40327?

A vulnerability in the Linux kernel has been identified where the async-profiler tool's cpu-clock usage can lead to a system hang. This issue stems from the interaction between the cpu-clock, a specialized software event relying on hrtimers, and the __perf_event_overflow() callback that is called from the hrtimer handler. When this callback attempts to stop the event, it creates a recursive call into the hrtimer code, resulting in a deadlock situation. The resolution involves using hrtimer_try_to_cancel() instead of the recursive call to prevent this hang, alongside setting the PERF_HES_STOPPED flag to ensure proper event management.

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