[IPv6]: Only modify checksum for UDP

Only change upper-layer checksum from 0 to 0xFFFF for UDP (as RFC 768
states), not for others as RFC 4443 doesn't require it.
Signed-off-by: NBrian Haley <brian.haley@hp.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv6/icmp.c

@@ -247,8 +247,6 @@ static int icmpv6_push_pending_frames(struct sock *sk, struct flowi *fl, struct
 					   len, fl->proto, tmp_csum);
 		icmp6h->icmp6_cksum = tmp_csum;
 	}
-	if (icmp6h->icmp6_cksum == 0)
-		icmp6h->icmp6_cksum = -1;
 	ip6_push_pending_frames(sk);
 out:
 	return err;

net/ipv6/raw.c

@@ -536,7 +536,7 @@ static int rawv6_push_pending_frames(struct sock *sk, struct flowi *fl,
 				   &fl->fl6_dst,
 				   total_len, fl->proto, tmp_csum);
 
-	if (tmp_csum == 0)
+	if (tmp_csum == 0 && fl->proto == IPPROTO_UDP)
 		tmp_csum = -1;
 
 	csum = tmp_csum;