tree 1268f3dcf973f8fc3d86c84d9b09ff9048647491
parent 179394af7a2baa1d0a3cb1670075310d72247d38
author Oleg Nesterov <oleg@tv-sign.ru> 1187816497 -0700
committer Linus Torvalds <torvalds@woody.linux-foundation.org> 1187837566 -0700

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>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>