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authorTakashi Iwai <tiwai@suse.de>2018-03-05 22:00:55 +0100
committerTakashi Iwai <tiwai@suse.de>2018-03-08 08:59:26 +0100
commitd85739367c6d56e475c281945c68fdb05ca74b4c (patch)
treedbe72abbd30b4eb2f85f2946d5c79ff42e886dbc /sound/core
parente312a869cd726c698a75caca0d9e5c22fd3f1534 (diff)
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ALSA: seq: Don't allow resizing pool in use
This is a fix for a (sort of) fallout in the recent commit d15d662e89fc ("ALSA: seq: Fix racy pool initializations") for CVE-2018-1000004. As the pool resize deletes the existing cells, it may lead to a race when another thread is writing concurrently, eventually resulting a UAF. A simple workaround is not to allow the pool resizing when the pool is in use. It's an invalid behavior in anyway. Fixes: d15d662e89fc ("ALSA: seq: Fix racy pool initializations") Reported-by: 范龙飞 <long7573@126.com> Reported-by: Nicolai Stange <nstange@suse.de> Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/core')
-rw-r--r--sound/core/seq/seq_clientmgr.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/sound/core/seq/seq_clientmgr.c b/sound/core/seq/seq_clientmgr.c
index 04d4db44fae5..d41ce3ed62ca 100644
--- a/sound/core/seq/seq_clientmgr.c
+++ b/sound/core/seq/seq_clientmgr.c
@@ -1838,6 +1838,9 @@ static int snd_seq_ioctl_set_client_pool(struct snd_seq_client *client,
(! snd_seq_write_pool_allocated(client) ||
info->output_pool != client->pool->size)) {
if (snd_seq_write_pool_allocated(client)) {
+ /* is the pool in use? */
+ if (atomic_read(&client->pool->counter))
+ return -EBUSY;
/* remove all existing cells */
snd_seq_pool_mark_closing(client->pool);
snd_seq_queue_client_leave_cells(client->number);