linux-kernel - [PATCH 3.2 43/87] ALSA: seq: Fix missing NULL check at remove

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Message-ID: <lsq.1454975631.533857396@decadent.org.uk>
Date:	Mon, 08 Feb 2016 23:53:51 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org, "Dmitry Vyukov" <dvyukov@...gle.com>,
	"Takashi Iwai" <tiwai@...e.de>
Subject: [PATCH 3.2 43/87] ALSA: seq: Fix missing NULL check at
 remove_events ioctl

3.2.77-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Takashi Iwai <tiwai@...e.de>

commit 030e2c78d3a91dd0d27fef37e91950dde333eba1 upstream.

snd_seq_ioctl_remove_events() calls snd_seq_fifo_clear()
unconditionally even if there is no FIFO assigned, and this leads to
an Oops due to NULL dereference.  The fix is just to add a proper NULL
check.

Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
Tested-by: Dmitry Vyukov <dvyukov@...gle.com>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 sound/core/seq/seq_clientmgr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/sound/core/seq/seq_clientmgr.c
+++ b/sound/core/seq/seq_clientmgr.c
@@ -1950,7 +1950,7 @@ static int snd_seq_ioctl_remove_events(s
 		 * No restrictions so for a user client we can clear
 		 * the whole fifo
 		 */
-		if (client->type == USER_CLIENT)
+		if (client->type == USER_CLIENT && client->data.user.fifo)
 			snd_seq_fifo_clear(client->data.user.fifo);
 	}