Messages in this thread Patch in this message | | | Date | Sun, 12 Aug 2007 23:59:04 +0400 | From | Oleg Nesterov <> | Subject | Re: [PATCH 2/4] posix-timers: fix creation race |
| |
On 08/12, Oleg Nesterov wrote: > > > > - spin_unlock_irqrestore(&process->sighand->siglock, flags); > > > process = NULL; > > > } > > > + spin_unlock_irqrestore(&process->sighand->siglock, flags); > > i'll resend this patch tomorrow. We can't do spin_unlock_irqrestore(&process->...) > if we set process = NULL above.
Another attempt, no cleanups, just a minimal fix for now.
[PATCH 2/4] 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 <oleg@tv-sign.ru>
--- t/kernel/posix-timers.c~ 2007-08-12 23:50:46.000000000 +0400 +++ t/kernel/posix-timers.c 2007-08-12 23:52:07.000000000 +0400 @@ -547,9 +547,9 @@ 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); + spin_unlock_irqrestore(&process->sighand->siglock, flags); } else { spin_unlock_irqrestore(&process->sighand->siglock, flags); process = NULL; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |