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authorOleg Nesterov <oleg@tv-sign.ru>2007-08-22 14:01:42 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-08-22 19:52:46 -0700
commit834d216e1f804560bd1421c511ad168d7c24b01d (patch)
treec245ab7814bc54c6f3b8aa877d2dd77c92450a76 /kernel
parentd02479bdeb1c9b037892061cdcf4e730183391fa (diff)
downloadlinux-linaro-834d216e1f804560bd1421c511ad168d7c24b01d.tar.gz
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/signal.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index b27c01a6644..ad63109e413 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -378,7 +378,7 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
/* We only dequeue private signals from ourselves, we don't let
* signalfd steal them
*/
- if (tsk == current)
+ if (likely(tsk == current))
signr = __dequeue_signal(&tsk->pending, mask, info);
if (!signr) {
signr = __dequeue_signal(&tsk->signal->shared_pending,
@@ -425,7 +425,7 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT))
tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
}
- if ( signr &&
+ if (signr && likely(tsk == current) &&
((info->si_code & __SI_MASK) == __SI_TIMER) &&
info->si_sys_private){
/*