[IPV6]: Fix leak added by udp connect dst caching fix.

Based upon a patch from Mitsuru KANDA <mk@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/udp.c

@@ -852,10 +852,16 @@ do_append_data:
 	else if (!corkreq)
 		err = udp_v6_push_pending_frames(sk, up);
 
-	if (dst && connected)
+	if (dst) {
+		if (connected) {
 			ip6_dst_store(sk, dst,
 				      ipv6_addr_equal(&fl->fl6_dst, &np->daddr) ?
 				      &np->daddr : NULL);
+		} else {
+			dst_release(dst);
+		}
+	}
+
 	if (err > 0)
 		err = np->recverr ? net_xmit_errno(err) : 0;
 	release_sock(sk);