From: Sasha Levin <sasha.levin@oracle.com>
Date: Fri, 5 Feb 2016 23:36:05 +0000 (-0800)
Subject: UPSTREAM: signals: avoid random wakeups in sigsuspend()
X-Git-Tag: firefly_0821_release~1268
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=2303a7faef52063c2b71861516fb4eddc5af03f6;p=firefly-linux-kernel-4.4.55.git

UPSTREAM: signals: avoid random wakeups in sigsuspend()

A random wakeup can get us out of sigsuspend() without TIF_SIGPENDING
being set.

Avoid that by making sure we were signaled, like sys_pause() does.

Change-Id: Ie647d2797416c6e53628174a07b62246e23081e7
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Huang, Tao <huangtao@rock-chips.com>
(cherry picked from commit 823dd3224a07f618d652a7743c9603222d019de3)
---

diff --git a/kernel/signal.c b/kernel/signal.c
index f3f1f7a972fd..0508544c8ced 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -3508,8 +3508,10 @@ static int sigsuspend(sigset_t *set)
 	current->saved_sigmask = current->blocked;
 	set_current_blocked(set);
 
-	__set_current_state(TASK_INTERRUPTIBLE);
-	schedule();
+	while (!signal_pending(current)) {
+		__set_current_state(TASK_INTERRUPTIBLE);
+		schedule();
+	}
 	set_restore_sigmask();
 	return -ERESTARTNOHAND;
 }