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Commit b323914c authored by Takashi Iwai's avatar Takashi Iwai Committed by Greg Kroah-Hartman
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ALSA: seq: Cover unsubscribe_port() in list_mutex 



commit 7c32ae35fbf9cffb7aa3736f44dec10c944ca18e 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: default avatar <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 3af96f34

sound/core/seq/seq_ports.c

+1 −1
Original line number Diff line number Diff line
@@ -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 */