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authorTakashi Iwai <tiwai@suse.de>2020-08-04 20:58:15 +0200
committerTakashi Iwai <tiwai@suse.de>2020-08-05 08:27:39 +0200
commit80982c7e834e5d4e325b6ce33757012ecafdf0bb (patch)
treeba9fb7af0995bfefbef4c4ad7cb23a3ad0a45546 /sound/core/seq
parentcd72c317a0a11f64225b9a3f1fe503bb8c7327b5 (diff)
ALSA: seq: oss: Serialize ioctls
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>
Diffstat (limited to 'sound/core/seq')
-rw-r--r--sound/core/seq/oss/seq_oss.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/sound/core/seq/oss/seq_oss.c b/sound/core/seq/oss/seq_oss.c
index 17f913657304..c8b9c0b315d8 100644
--- a/sound/core/seq/oss/seq_oss.c
+++ b/sound/core/seq/oss/seq_oss.c
@@ -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