Description
In the Linux kernel, the following vulnerability has been resolved: sched_ext: Keep kick_sync waiting on the rq's own CPU kick_sync_wait_bal_cb() assumes it runs on the rq's CPU from the __schedule() tail: the snapshots it compares against live in that CPU's percpu area and the busy-wait runs with the rq lock dropped and IRQs enabled. However, dispatch can now drop the rq lock while the callback sits queued, and rq lock takers in that window (the sched class change paths, the scx task iterator) flush pending balance callbacks on release, running the callback on a foreign CPU. Such a run compares against unrelated snapshots and can deadlock when the executing CPU is itself a wait target. Bail on a foreign CPU and leave the wait state alone. The wait only observes progress that the resched kicks already guarantee and the rq's next wait picks up the stale cpus_to_sync bits.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
4c95380701f58b8112f0b891de8d160e4199e19d to < c736ea0fe7b4df920da6bd43a81c5eeecadcc8beaffected4c95380701f58b8112f0b891de8d160e4199e19d to < e0253dd04beb03e79477c5ef4768b11135687206affected
Linux Linux
Default version status: affected
6.19affected0 to < 6.19unaffected7.2.4 to ≤ 7.2.*unaffected7.3 to ≤ *unaffected