]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commit
signalfd: fix interaction with posix-timers
authorOleg Nesterov <oleg@tv-sign.ru>
Wed, 22 Aug 2007 21:01:42 +0000 (14:01 -0700)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>
Thu, 23 Aug 2007 02:52:46 +0000 (19:52 -0700)
commit834d216e1f804560bd1421c511ad168d7c24b01d
treec245ab7814bc54c6f3b8aa877d2dd77c92450a76
parentd02479bdeb1c9b037892061cdcf4e730183391fa
signalfd: fix interaction with posix-timers

dequeue_signal:

if (__SI_TIMER) {
spin_unlock(&tsk->sighand->siglock);
do_schedule_next_timer(info);
spin_lock(&tsk->sighand->siglock);
}

Unless tsk == curent, this is absolutely unsafe: nothing prevents tsk from
exiting. If signalfd was passed to another process, do_schedule_next_timer()
is just wrong.

Add yet another "tsk == current" check into dequeue_signal().

This patch fixes an oopsable bug, but breaks the scheduling of posix timers
if the shared __SI_TIMER signal was fetched via signalfd attached to another
sub-thread. Mostly fixed by the next patch.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: Roland McGrath <roland@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kernel/signal.c