From: Takashi Iwai <tiwai@suse.de>
Date: Mon, 8 Aug 2011 10:24:46 +0000 (+0200)
Subject: ALSA: timer - Fix Oops at closing slave timer
X-Git-Tag: v2.6.33.18~4
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0ef6e5ad8910506f865cf5d4d6399035b9d92aa5;p=thirdparty%2Fkernel%2Fstable.git

ALSA: timer - Fix Oops at closing slave timer

commit 0584ffa548b6e59aceb027112f23a55f0133400e upstream.

A slave-timer instance has no timer reference, and this results in
NULL-dereference at stopping the timer, typically called at closing
the device.

Reference: https://bugzilla.kernel.org/show_bug.cgi?id=40682

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/sound/core/timer.c b/sound/core/timer.c
index 8f8b17ac074df..4a138441f7992 100644
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -530,6 +530,8 @@ int snd_timer_stop(struct snd_timer_instance *timeri)
 	if (err < 0)
 		return err;
 	timer = timeri->timer;
+	if (!timer)
+		return -EINVAL;
 	spin_lock_irqsave(&timer->lock, flags);
 	timeri->cticks = timeri->ticks;
 	timeri->pticks = 0;