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| author | Oleg Nesterov <oleg@tv-sign.ru> | 2007-08-22 14:01:42 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-08-22 19:52:46 -0700 |
| commit | 834d216e1f804560bd1421c511ad168d7c24b01d (patch) | |
| tree | c245ab7814bc54c6f3b8aa877d2dd77c92450a76 /kernel/signal.c | |
| parent | d02479bdeb1c9b037892061cdcf4e730183391fa (diff) | |
| download | lwn-834d216e1f804560bd1421c511ad168d7c24b01d.tar.gz lwn-834d216e1f804560bd1421c511ad168d7c24b01d.zip | |
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/signal.c')
| -rw-r--r-- | kernel/signal.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/signal.c b/kernel/signal.c index b27c01a66448..ad63109e413c 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){ /* |