diff options
| author | Takashi Iwai <tiwai@suse.de> | 2018-03-05 22:00:55 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-03-18 11:17:50 +0100 |
| commit | 2b1d533fb743a2bb32fc4eaafa2d4fd21d909d34 (patch) | |
| tree | af7ed74cc1d8e66efee7657edd9f97055e17d518 | |
| parent | c90b35bce4f3a79c015513601ae25fb8469363eb (diff) | |
ALSA: seq: Don't allow resizing pool in use
commit d85739367c6d56e475c281945c68fdb05ca74b4c upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | sound/core/seq/seq_clientmgr.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/sound/core/seq/seq_clientmgr.c b/sound/core/seq/seq_clientmgr.c index 167b943469ab..d564e6c6426c 100644 --- a/sound/core/seq/seq_clientmgr.c +++ b/sound/core/seq/seq_clientmgr.c @@ -1924,6 +1924,9 @@ 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); |