udpv6: Fix gso_size setting in ip6_ufo_append_data

- fix gso_size setting for ipv6 fragment to be a multiple of 8 bytes.
Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/ip6_output.c

@@ -1087,9 +1087,11 @@ static inline int ip6_ufo_append_data(struct sock *sk,
 	if (!err) {
 		struct frag_hdr fhdr;
 
-		/* specify the length of each IP datagram fragment*/
-		skb_shinfo(skb)->gso_size = mtu - fragheaderlen -
-					    sizeof(struct frag_hdr);
+		/* Specify the length of each IPv6 datagram fragment.
+		 * It has to be a multiple of 8.
+		 */
+		skb_shinfo(skb)->gso_size = (mtu - fragheaderlen -
+					     sizeof(struct frag_hdr)) & ~7;
 		skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
 		ipv6_select_ident(skb, &fhdr);
 		skb_shinfo(skb)->ip6_frag_id = fhdr.identification;