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authorTakashi Iwai <tiwai@suse.de>2019-04-12 11:37:19 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-06-15 11:54:11 +0200
commitb323914cd033f975b5d544b188a3ed1948f02936 (patch)
tree47bb2b7152a4893fcb7c57e6dd5278bdf8732869
parent3af96f3497b7ee087ce2bc5feae1390f57b87dc7 (diff)
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 <tiwai@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--sound/core/seq/seq_ports.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/sound/core/seq/seq_ports.c b/sound/core/seq/seq_ports.c
index 24d90abfc64d..da31aa8e216e 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 */