Messages in this thread Patch in this message | | | Date | Sat, 3 May 2008 21:35:54 +0400 | From | Oleg Nesterov <> | Subject | [PATCH 4/4] posix timers: release_posix_timer: kill the bogus put_task_struct(->it_process); |
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release_posix_timer() can't be called with ->it_process != NULL. Once sys_timer_create() sets ->it_process it must not call release_posix_timer(), otherwise we can race with another thread doing sys_timer_delete(), this timer is visible to idr_find() and unlocked.
The same is true for two other callers (actually, for any possible caller), sys_timer_delete() and itimer_delete(). They must clear ->it_process before unlock_timer() + release_posix_timer().
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
--- 25/kernel/posix-timers.c~4_RPT_NO_CHECK 2008-05-03 19:55:27.000000000 +0400 +++ 25/kernel/posix-timers.c 2008-05-03 20:13:36.000000000 +0400 @@ -450,9 +450,6 @@ static void release_posix_timer(struct k spin_unlock_irqrestore(&idr_lock, flags); } sigqueue_free(tmr->sigq); - if (unlikely(tmr->it_process) && - tmr->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID)) - put_task_struct(tmr->it_process); kmem_cache_free(posix_timers_cache, tmr); }
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