Commit bc9dcb27 authored by Takashi Iwai's avatar Takashi Iwai Committed by Greg Kroah-Hartman

ALSA: seq: Cover unsubscribe_port() in list_mutex

commit 7c32ae35 upstream.

The call of unsubscribe_port() which manages the group count and
module refcount from delete_and_unsubscribe_port() looks racy; it's
not covered by the group list lock, and it's likely a cause of the
reported unbalance at port deletion.  Let's move the call inside the
group list_mutex to plug the hole.

Reported-by: syzbot+e4c8abb920efa77bace9@syzkaller.appspotmail.com
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent f40c32fd
......@@ -550,10 +550,10 @@ static void delete_and_unsubscribe_port(struct snd_seq_client *client,
list_del_init(list);
grp->exclusive = 0;
write_unlock_irq(&grp->list_lock);
up_write(&grp->list_mutex);
if (!empty)
unsubscribe_port(client, port, grp, &subs->info, ack);
up_write(&grp->list_mutex);
}
/* connect two ports */
......
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