Bluetooth: L2CAP: Fix null-ptr-deref in l2cap_sock_new_connection_cb()

commit 0a120d9 upstream.

Add the same NULL guard already present in
l2cap_sock_resume_cb() and l2cap_sock_ready_cb().

Fixes: 80808e4 ("Bluetooth: Add l2cap_chan_ops abstraction")
Cc: stable@kernel.org
Signed-off-by: Siwei Zhang <oss@fourdim.xyz>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: fourdim

net/bluetooth/l2cap_sock.c

@@ -1498,6 +1498,9 @@ static struct l2cap_chan *l2cap_sock_new_connection_cb(struct l2cap_chan *chan)
 {
 	struct sock *sk, *parent = chan->data;
 
+	if (!parent)
+		return NULL;
+
 	lock_sock(parent);
 
 	/* Check for backlog size */