[PATCH 3.2 43/87] ALSA: seq: Fix missing NULL check at remove_events ioctl

From: Ben Hutchings
Date: Mon Feb 08 2016 - 19:07:25 EST


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

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

From: Takashi Iwai <tiwai@xxxxxxx>

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@xxxxxxxxxx>
Tested-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
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);
}