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 _perfeventoverflow() callback is invoked from the hrtimer handler for cpu-clock events, and _perfeventoverflow() tries to call cpuclockeventstop() to stop the event, which calls htimercancel() 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 hrtimertrytocancel() instead, and set the PERFHESSTOPPED flag, which causes perfsweventhrtimer() to stop the event once it sees the PERFHES_STOPPED flag.
[ mingo: Fixed the comments and improved the changelog. ]
{
"cna_assigner": "Linux",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/40xxx/CVE-2025-40327.json"
}