CVSS
Вероятност да бъде експлоатирана в следващите 30 дни (EPSS)
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Време до експлоатация
Описание
Оригинално описание
In the Linux kernel, the following vulnerability has been resolved: sched_ext: Fix rq->core_pick corruption under core scheduling Core scheduling's pick_next_task() picks what to run on every SMT sibling of the core in a single pass under the shared core-wide rq lock. The selection state is consistent only while the lock is held continuously, so ->pick_task() originally could not release it. However, since 4c95380701f5 ("sched/ext: Fold balance_scx() into pick_task_scx()"), sched_ext runs dispatch from inside the pick and dispatching can drop the rq lock. To support this, pick_next_task() has been updated to restart the whole selection when a pick returns RETRY_TASK after releasing the lock. When selections on the same core interleave through the dropped lock, they corrupt each other's state: one clears the other's rq->core_pick leading to a NULL deref, or invalidates its keep-the-previous-task decision leaving a dequeued task running, which deadlocks the next wakeup and matches the reported hard hangs. A cookied ping-pong load on an SMT machine makes the interleavings frequent and kills the kernel within seconds. Fix it by making the pick return RETRY_TASK whenever dispatch released the rq lock, so that a selection only ever commits picks made under a continuously held lock. The previous patch's rq->scx.lock_drop_seq counts the releases. A dispatch that touched nothing never releases the lock and its verdict, including "nothing to run", stands: retries are bounded, each following a dispatch that actually did something, and an idle CPU does not loop. If another dispatch is already in flight on the rq, skip dispatching and pick from what is already queued locally - the in-flight dispatch has released the lock, so its own selection will retry and re-pick this rq, while returning RETRY_TASK here would only spin on the lock that dispatch needs to finish. Balance callbacks must run in the context that queued them, so they can only be queued on the CPU's own rq. Whe
Засегнати продукти
- Linux Linux: 4c95380701f58b8112f0b891de8d160e4199e19d преди cdafb68155bee2d5c4e50c12e4606323e9334e6b; 4c95380701f58b8112f0b891de8d160e4199e19d преди d954004205c1a1d3f59ce8482b559266c15600fa
- Linux Linux: 6.19; преди 6.19; 7.2.4 до 7.2.*; от 7.3 нататък
История
- 11 септември 2026 Публикувано