ipv4: Don't ip_rt_put() an error pointer in RAW sockets.

Reported-by: NMarc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/raw.c

@@ -569,6 +569,7 @@ static int raw_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 		rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
 		if (IS_ERR(rt)) {
 			err = PTR_ERR(rt);
+			rt = NULL;
 			goto done;
 		}
 	}