From: Takashi Iwai Date: Fri, 12 Apr 2019 09:37:19 +0000 (+0200) Subject: ALSA: seq: Cover unsubscribe_port() in list_mutex X-Git-Tag: v4.19.51~1 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=b323914cd033f975b5d544b188a3ed1948f02936;p=platform%2Fkernel%2Flinux-rpi.git 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: syzbot+e4c8abb920efa77bace9@syzkaller.appspotmail.com Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- diff --git a/sound/core/seq/seq_ports.c b/sound/core/seq/seq_ports.c index 24d90ab..da31aa8 100644 --- a/sound/core/seq/seq_ports.c +++ b/sound/core/seq/seq_ports.c @@ -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 */