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

Reported-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index e837ffd..2d3c72e 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -569,6 +569,7 @@
 		rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
 		if (IS_ERR(rt)) {
 			err = PTR_ERR(rt);
+			rt = NULL;
 			goto done;
 		}
 	}