Bluetooth: SCO - Fix missing msg_namelen update in sco_sock_recvmsg()

If the socket is in state BT_CONNECT2 and BT_SK_DEFER_SETUP is set in
the flags, sco_sock_recvmsg() returns early with 0 without updating the
possibly set msg_namelen member. This, in turn, leads to a 128 byte
kernel stack leak in net/socket.c.

Fix this by updating msg_namelen in this case. For all other cases it
will be handled in bt_sock_recvmsg().

Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: Johan Hedberg <johan.hedberg@gmail.com>
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
static int sco_sock_shutdown(struct socket *sock, int how)
{
	struct sock *sk = sock->sk;
	int err = 0;

	BT_DBG("sock %p, sk %p", sock, sk);

	if (!sk)
		return 0;

	lock_sock(sk);
	if (!sk->sk_shutdown) {
		sk->sk_shutdown = SHUTDOWN_MASK;
		sco_sock_clear_timer(sk);
		__sco_sock_close(sk);

		if (sock_flag(sk, SOCK_LINGER) && sk->sk_lingertime)
			err = bt_sock_wait_state(sk, BT_CLOSED,
						 sk->sk_lingertime);
	}
	release_sock(sk);
	return err;
}

static int sco_sock_shutdown(struct socket *sock, int how)
{
	struct sock *sk = sock->sk;
	int err = 0;

	BT_DBG("sock %p, sk %p", sock, sk);

	if (!sk)
		return 0;

	lock_sock(sk);
	if (!sk->sk_shutdown) {
		sk->sk_shutdown = SHUTDOWN_MASK;
		sco_sock_clear_timer(sk);
		__sco_sock_close(sk);

		if (sock_flag(sk, SOCK_LINGER) && sk->sk_lingertime)
			err = bt_sock_wait_state(sk, BT_CLOSED,
						 sk->sk_lingertime);
	}
	release_sock(sk);
	return err;
}
