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authorPeter Zijlstra <peterz@infradead.org>2022-11-24 12:49:12 +0100
committerPeter Zijlstra <peterz@infradead.org>2022-11-29 17:42:49 +0100
commit517e6a301f34613bff24a8e35b5455884f2d83d8 (patch)
treeb68b636c5defda5acaf08265087297172771655d /drivers/block/ublk_drv.c
parent030a976efae83f7b6593afb11a8254d42f9290fe (diff)
downloadlinux-517e6a301f34613bff24a8e35b5455884f2d83d8.tar.gz
perf: Fix perf_pending_task() UaF
Per syzbot it is possible for perf_pending_task() to run after the event is free()'d. There are two related but distinct cases: - the task_work was already queued before destroying the event; - destroying the event itself queues the task_work. The first cannot be solved using task_work_cancel() since perf_release() itself might be called from a task_work (____fput), which means the current->task_works list is already empty and task_work_cancel() won't be able to find the perf_pending_task() entry. The simplest alternative is extending the perf_event lifetime to cover the task_work. The second is just silly, queueing a task_work while you know the event is going away makes no sense and is easily avoided by re-arranging how the event is marked STATE_DEAD and ensuring it goes through STATE_OFF on the way down. Reported-by: syzbot+9228d6098455bb209ec8@syzkaller.appspotmail.com Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Marco Elver <elver@google.com>
Diffstat (limited to 'drivers/block/ublk_drv.c')
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