--- /dev/null
+From 7c32ae35fbf9cffb7aa3736f44dec10c944ca18e Mon Sep 17 00:00:00 2001
+From: Takashi Iwai <tiwai@suse.de>
+Date: Fri, 12 Apr 2019 11:37:19 +0200
+Subject: ALSA: seq: Cover unsubscribe_port() in list_mutex
+
+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 */