sched/psi: Shut down rtpoll_timer in psi_cgroup_free()

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-74594
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-22 16:16:31 UTC
Updated2026-08-22 16:16:31 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: sched/psi: Shut down rtpoll_timer in psi_cgroup_free() psi_schedule_rtpoll_work() is called locklessly from the scheduler hotpath and can race psi_trigger_destroy() taking down the last rtpoll trigger under rtpoll_trigger_lock: psi_schedule_rtpoll_work() psi_trigger_destroy() rcu_read_lock(); task = rcu_dereference(rtpoll_task); rcu_assign_pointer(rtpoll_task, NULL); timer_delete(&rtpoll_timer); mod_timer(&rtpoll_timer, ...); rcu_read_unlock(); synchronize_rcu(); kthread_stop(task_to_destroy); The group can then be freed with the re-armed timer still pending, and poll_timer_fn() runs on freed memory. 461daba06bdc ("psi: eliminate kthread_worker from psi trigger scheduling mechanism") deleted the timer synchronously after the synchronize_rcu(), which prevented this but raced trigger creation instead: the deletion could cancel the timer that a new trigger set armed during the grace period and, as creation also reinitialized the timer at the time, corrupt it. 8f91efd870ea ("psi: Fix race between psi_trigger_create/destroy") moved the initialization into group_init() and the deletion into the locked section, trading the creation races for the window above. Neither placement in the destruction path works. A pending timer firing while the group is alive is harmless though. poll_timer_fn() just wakes the rtpoll waitqueue and doesn't re-arm itself. Bind the timer to the group's lifetime instead and shut it down in psi_cgroup_free(). Nothing can arm it by then. timer_shutdown_sync() because the timer is never armed again.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 8f91efd870ea5d8bc10b0fcc9740db51cd4c0c83 1e5ca82eee59caca6988f9d6e859786aab8a5fa0 git Not specified
CNA Linux Linux affected 8f91efd870ea5d8bc10b0fcc9740db51cd4c0c83 310b5a537a78c358a4cd244bd767c1a517a05459 git Not specified
CNA Linux Linux affected 8f91efd870ea5d8bc10b0fcc9740db51cd4c0c83 806fcff98c1d7cb3c1dc0015e55ebdbe819e6b08 git Not specified
CNA Linux Linux affected 8f91efd870ea5d8bc10b0fcc9740db51cd4c0c83 8037c5b2b2a447df52542f4d8535895d837bdcbd git Not specified
CNA Linux Linux affected 8f91efd870ea5d8bc10b0fcc9740db51cd4c0c83 611e7821c4f83a671455658797336faecc3a5196 git Not specified
CNA Linux Linux affected 8f91efd870ea5d8bc10b0fcc9740db51cd4c0c83 5457025fa8ca3c0d2732109513de839e3e797190 git Not specified
CNA Linux Linux affected 6bfcb6178925b1fd28c102e53d403091b8f49396 git Not specified
CNA Linux Linux affected e1e5e263bbe0e6e9c3db36aa48a3c8acf546fa49 git Not specified
CNA Linux Linux affected 979965c33f734a1666af67900408f997ac669c23 git Not specified
CNA Linux Linux affected 5.10.50 5.11 semver Not specified
CNA Linux Linux affected 5.12.17 5.13 semver Not specified
CNA Linux Linux affected 5.13.2 5.14 semver Not specified
CNA Linux Linux affected 5.14 Not specified
CNA Linux Linux unaffected 5.14 semver Not specified
CNA Linux Linux unaffected 6.1.183 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.152 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.104 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.45 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.9 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/806fcff98c1d7cb3c1dc0015e55ebdbe819e6b08 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/611e7821c4f83a671455658797336faecc3a5196 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/5457025fa8ca3c0d2732109513de839e3e797190 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/1e5ca82eee59caca6988f9d6e859786aab8a5fa0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/310b5a537a78c358a4cd244bd767c1a517a05459 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8037c5b2b2a447df52542f4d8535895d837bdcbd 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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