Bluetooth: bnep: bnep_add_connection() should verify that it's dealing with l2cap socket

same story as cmtp
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/bnep/core.c

@@ -533,6 +533,9 @@ int bnep_add_connection(struct bnep_connadd_req *req, struct socket *sock)
 
 	BT_DBG("");
 
+	if (!l2cap_is_socket(sock))
+		return -EBADFD;
+
 	baswap((void *) dst, &l2cap_pi(sock->sk)->chan->dst);
 	baswap((void *) src, &l2cap_pi(sock->sk)->chan->src);