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 <[EMAIL PROTECTED]>
--- 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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