Messages in this thread | | | Subject | Re: [PATCH 2/4] posix-timers: fix creation race | From | Thomas Gleixner <> | Date | Sun, 12 Aug 2007 21:05:55 +0200 |
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On Sun, 2007-08-12 at 21:05 +0400, Oleg Nesterov wrote: > 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 <oleg@tv-sign.ru>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
> --- t/kernel/posix-timers.c~2_CREATE 2007-08-12 17:59:17.000000000 +0400 > +++ t/kernel/posix-timers.c 2007-08-12 18:11:33.000000000 +0400 > @@ -547,13 +547,12 @@ sys_timer_create(const clockid_t which_c > 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); > } else { > - spin_unlock_irqrestore(&process->sighand->siglock, flags); > process = NULL; > } > + spin_unlock_irqrestore(&process->sighand->siglock, flags); > } > read_unlock(&tasklist_lock); > if (!process) { >
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