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authorOleg Nesterov <oleg@tv-sign.ru>2008-05-23 16:04:41 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-05-24 12:56:10 -0400
commitda7978b0348d497688541e2d2f5739aa2a2c334f (patch)
treef4f55bf4293ff203f598e7a57959da1c5a7ad295 /kernel/signal.c
parentdfc7064500061677720fa26352963c772d3ebe6b (diff)
signals: fix sigqueue_free() vs __exit_signal() race
__exit_signal() does flush_sigqueue(tsk->pending) outside of ->siglock. This can race with another thread doing sigqueue_free(), we can free the same SIGQUEUE_PREALLOC sigqueue twice or corrupt the pending->list. Note that even sys_exit_group() can trigger this race, not only sys_timer_delete(). Move the callsite of flush_sigqueue(tsk->pending) under ->siglock. This patch doesn't touch flush_sigqueue(->shared_pending) below, it is called when there are no other threads which can play with signals, and sigqueue_free() can't be used outside of our thread group. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Acked-by: Roland McGrath <roland@redhat.com> 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.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index 72bb4f51f963..12ffea7c201d 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1242,7 +1242,8 @@ void sigqueue_free(struct sigqueue *q)
1242 /* 1242 /*
1243 * If the signal is still pending remove it from the 1243 * If the signal is still pending remove it from the
1244 * pending queue. We must hold ->siglock while testing 1244 * pending queue. We must hold ->siglock while testing
1245 * q->list to serialize with collect_signal(). 1245 * q->list to serialize with collect_signal() or with
1246 * __exit_signal()->flush_sigqueue().
1246 */ 1247 */
1247 spin_lock_irqsave(lock, flags); 1248 spin_lock_irqsave(lock, flags);
1248 if (!list_empty(&q->list)) 1249 if (!list_empty(&q->list))