From: Takashi Iwai tiwai@suse.de
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: syzbot+e4c8abb920efa77bace9@syzkaller.appspotmail.com Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- sound/core/seq/seq_ports.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/sound/core/seq/seq_ports.c +++ b/sound/core/seq/seq_ports.c @@ -550,10 +550,10 @@ static void delete_and_unsubscribe_port( 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 */