ALSA: rawmidi: Fix missing input substream checks in compat ioctls

commit 8a56ef4f3f upstream.

Some rawmidi compat ioctls lack of the input substream checks
(although they do check only for rfile->output).  This many eventually
lead to an Oops as NULL substream is passed to the rawmidi core
functions.

Fix it by adding the proper checks before each function call.

The bug was spotted by syzkaller.

Reported-by: syzbot+f7a0348affc3b67bc617@syzkaller.appspotmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
This commit is contained in:
Takashi Iwai 2018-04-19 18:16:15 +02:00 • committed by Ben Hutchings
commit 96d879e5b6