CVE-2025-40327

A flaw was found in the Linux kernel's perf subsystem. When using cpu-clock events, the __perf_event_overflow() callback is invoked from an hrtimer handler. This callback attempts to stop the event by calling cpu_clock_event_stop(), which in turn calls hrtimer_cancel() to cancel the hrtimer. This results in recursive entry into the hrtimer code from within an hrtimer handler, causing a deadlock and system hang. A local user with the ability to create perf events could exploit this to cause a denial of service.

This issue affects systems where local users can create perf cpu-clock events. The vulnerability requires local access and the ability to use the perf_event_open() system call, which may be restricted by the kernel.perf_event_paranoid sysctl setting. Exploitation leads to a system hang requiring a reboot to recover.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.