redonkable
/
alistair23-linux
1
0
Fork 0
Code Releases Activity

ALSA: seq: oss: Serialize ioctls 

commit 80982c7e83 upstream.

Some ioctls via OSS sequencer API may race and lead to UAF when the
port create and delete are performed concurrently, as spotted by a
couple of syzkaller cases.  This patch is an attempt to address it by
serializing the ioctls with the existing register_mutex.

Basically OSS sequencer API is an obsoleted interface and was designed
without much consideration of the concurrency.  There are very few
applications with it, and the concurrent performance isn't asked,
hence this "big hammer" approach should be good enough.

Reported-by: syzbot+1a54a94bd32716796edd@syzkaller.appspotmail.com
Reported-by: syzbot+9d2abfef257f3e2d4713@syzkaller.appspotmail.com
Suggested-by: Hillf Danton <hdanton@sina.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200804185815.2453-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
5.4-rM2-2.2.x-imx-squashed
Takashi Iwai 2020-08-04 20:58:15 +02:00 committed by Greg Kroah-Hartman
parent 3ebdc7b619
commit 4d81a7bdd3
1 changed files with 7 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
sound/core/seq/oss/seq_oss.c
View File

@ -168,10 +168,16 @@ static long
odev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct seq_oss_devinfo *dp;
long rc;
dp = file->private_data;
if (snd_BUG_ON(!dp))
return -ENXIO;
return snd_seq_oss_ioctl(dp, cmd, arg);
mutex_lock(&register_mutex);
rc = snd_seq_oss_ioctl(dp, cmd, arg);
mutex_unlock(&register_mutex);
return rc;
}
#ifdef CONFIG_COMPAT