Bluetooth: L2CAP: fix "bad unlock balance" in l2cap_disconnect_rsp

conn->chan_lock isn't acquired before l2cap_get_chan_by_scid,
if l2cap_get_chan_by_scid returns NULL, then 'bad unlock balance'
is triggered.

Reported-by: syzbot+9519d6b5b79cf7787cf3@syzkaller.appspotmail.com
Link: https://lore.kernel.org/all/000000000000894f5f05f95e9f4d@google.com/
Signed-off-by: Min Li <lm0963hack@gmail.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 5cc95fd17f7d6f36894f45aa740cac1b924d10e3..376b523c7b268beb37b5a6fb8fb8409fd32d0851 100644 (file)
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -4693,7 +4693,6 @@ static inline int l2cap_disconnect_rsp(struct l2cap_conn *conn,
 
        chan = l2cap_get_chan_by_scid(conn, scid);
        if (!chan) {
-               mutex_unlock(&conn->chan_lock);
                return 0;
        }