CVE-2026-74594: Linux

High severity, CVSS 7.8. EPSS: 0.1% chance of exploitation in the next 30 days.

In 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.

Affected products

• Linux Linux: from 5.10.50, before 5.10.266 (fixed in 5.10.266); from 5.12.17, before 5.13 (fixed in 5.13); from 5.13.2, before 5.14 (fixed in 5.14); from 5.14, before 5.15.217 (fixed in 5.15.217); from 5.16, before 6.1.183 (fixed in 6.1.183); from 6.2, before 6.6.152 (fixed in 6.6.152); …

Published 2026-08-22. Last modified 2026-08-25.