This is a note to let you know that I've just added the patch titled
ALSA: seq: Clear client entry before deleting else at closing
to the 3.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
alsa-seq-clear-client-entry-before-deleting-else-at-closing.patch
and it can be found in the queue-3.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From a2ff19f7b70118ced291a28d5313469914de451b Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@xxxxxxx>
Date: Fri, 9 Mar 2018 22:23:31 +0100
Subject: ALSA: seq: Clear client entry before deleting else at closing
From: Takashi Iwai <tiwai@xxxxxxx>
commit a2ff19f7b70118ced291a28d5313469914de451b upstream.
When releasing a client, we need to clear the clienttab[] entry at
first, then call snd_seq_queue_client_leave(). Otherwise, the
in-flight cell in the queue might be picked up by the timer interrupt
via snd_seq_check_queue() before calling snd_seq_queue_client_leave(),
and it's delivered to another queue while the client is clearing
queues. This may eventually result in an uncleared cell remaining in
a queue, and the later snd_seq_pool_delete() may need to wait for a
long time until the event gets really processed.
By moving the clienttab[] clearance at the beginning of release, any
event delivery of a cell belonging to this client will fail at a later
point, since snd_seq_client_ptr() returns NULL. Thus the cell that
was picked up by the timer interrupt will be returned immediately
without further delivery, and the long stall of snd_seq_delete_pool()
can be avoided, too.
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
sound/core/seq/seq_clientmgr.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/sound/core/seq/seq_clientmgr.c
+++ b/sound/core/seq/seq_clientmgr.c
@@ -270,12 +270,12 @@ static int seq_free_client1(struct snd_s
if (!client)
return 0;
- snd_seq_delete_all_ports(client);
- snd_seq_queue_client_leave(client->number);
spin_lock_irqsave(&clients_lock, flags);
clienttablock[client->number] = 1;
clienttab[client->number] = NULL;
spin_unlock_irqrestore(&clients_lock, flags);
+ snd_seq_delete_all_ports(client);
+ snd_seq_queue_client_leave(client->number);
snd_use_lock_sync(&client->use_lock);
snd_seq_queue_client_termination(client->number);
if (client->pool)
Patches currently in stable-queue which might be from tiwai@xxxxxxx are
queue-3.18/alsa-pcm-fix-uaf-in-snd_pcm_oss_get_formats.patch
queue-3.18/alsa-seq-fix-possible-uaf-in-snd_seq_check_queue.patch
queue-3.18/alsa-seq-clear-client-entry-before-deleting-else-at-closing.patch