tree 301264d814fae494155ae518c42f380666623ef6
parent 1dcb1859dd6752131b85c78fb3e440bd1d2cf361
author Takashi Iwai <tiwai@suse.de> 1518445251 +0100
committer Takashi Iwai <tiwai@suse.de> 1518601148 +0100

ALSA: seq: Fix racy pool initializations

ALSA sequencer core initializes the event pool on demand by invoking
snd_seq_pool_init() when the first write happens and the pool is
empty.  Meanwhile user can reset the pool size manually via ioctl
concurrently, and this may lead to UAF or out-of-bound accesses since
the function tries to vmalloc / vfree the buffer.

A simple fix is to just wrap the snd_seq_pool_init() call with the
recently introduced client->ioctl_mutex; as the calls for
snd_seq_pool_init() from other side are always protected with this
mutex, we can avoid the race.

Reported-by: 范龙飞 <long7573@126.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>