From: Oleg Nesterov Date: Wed, 22 Aug 2007 21:01:37 +0000 (-0700) Subject: posix-timers: fix creation race X-Git-Tag: v3.12-rc1~27098 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=d02479bdeb1c9b037892061cdcf4e730183391fa;p=kernel%2Fkernel-generic.git posix-timers: fix creation race sys_timer_create() sets ->it_process and unlocks ->siglock, then checks tmr->it_sigev_notify to define if get_task_struct() is needed. We already passed ->it_id to the caller, another thread can delete this timer and free its memory in between. As a minimal fix, move this code under ->siglock, sys_timer_delete() takes it too before calling release_posix_timer(). A proper serialization would be to take ->it_lock, we add a partly initialized timer on posix_timers_id, not good. Signed-off-by: Oleg Nesterov Cc: Thomas Gleixner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index 6923ad8..7a15afb 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -547,9 +547,9 @@ sys_timer_create(const clockid_t which_clock, new_timer->it_process = process; list_add(&new_timer->list, &process->signal->posix_timers); - spin_unlock_irqrestore(&process->sighand->siglock, flags); if (new_timer->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID)) get_task_struct(process); + spin_unlock_irqrestore(&process->sighand->siglock, flags); } else { spin_unlock_irqrestore(&process->sighand->siglock, flags); process = NULL;