Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=834d216e1f804560bd1421c511ad168d7c24b01d
Commit: 834d216e1f804560bd1421c511ad168d7c24b01d
Parent: d02479bdeb1c9b037892061cdcf4e730183391fa
Author: Oleg Nesterov <[EMAIL PROTECTED]>
AuthorDate: Wed Aug 22 14:01:42 2007 -0700
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Wed Aug 22 19:52:46 2007 -0700
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 <[EMAIL PROTECTED]>
Cc: Benjamin Herrenschmidt <[EMAIL PROTECTED]>
Cc: Davide Libenzi <[EMAIL PROTECTED]>
Cc: Ingo Molnar <[EMAIL PROTECTED]>
Cc: Michael Kerrisk <[EMAIL PROTECTED]>
Cc: Roland McGrath <[EMAIL PROTECTED]>
Cc: Thomas Gleixner <[EMAIL PROTECTED]>
Cc: <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
kernel/signal.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/signal.c b/kernel/signal.c
index b27c01a..ad63109 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){
/*
-
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