Revert "udp: consistently apply ufo or fragmentation"

This reverts commit 840d468d.

CVE-2017-1000112
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

net/ipv4/ip_output.c

@@ -922,12 +922,11 @@ static int __ip_append_data(struct sock *sk,
 		csummode = CHECKSUM_PARTIAL;
 
 	cork->length += length;
-	if ((skb && skb_is_gso(skb)) ||
-	    (((length + (skb ? skb->len : fragheaderlen)) > mtu) &&
-	    (skb_queue_len(queue) <= 1) &&
+	if ((((length + (skb ? skb->len : fragheaderlen)) > mtu) ||
+	     (skb && skb_is_gso(skb))) &&
 	    (sk->sk_protocol == IPPROTO_UDP) &&
 	    (rt->dst.dev->features & NETIF_F_UFO) && !dst_xfrm(&rt->dst) &&
-	    (sk->sk_type == SOCK_DGRAM) && !sk->sk_no_check_tx)) {
+	    (sk->sk_type == SOCK_DGRAM) && !sk->sk_no_check_tx) {
 		err = ip_ufo_append_data(sk, queue, getfrag, from, length,
 					 hh_len, fragheaderlen, transhdrlen,
 					 maxfraglen, flags);
@@ -1243,7 +1242,6 @@ ssize_t	ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
 		return -EINVAL;
 
 	if ((size + skb->len > mtu) &&
-	    (skb_queue_len(&sk->sk_write_queue) == 1) &&
 	    (sk->sk_protocol == IPPROTO_UDP) &&
 	    (rt->dst.dev->features & NETIF_F_UFO)) {
 		if (skb->ip_summed != CHECKSUM_PARTIAL)

net/ipv6/ip6_output.c

@@ -1361,12 +1361,11 @@ static int __ip6_append_data(struct sock *sk,
 	 */
 
 	cork->length += length;
-	if ((skb && skb_is_gso(skb)) ||
-	    (((length + (skb ? skb->len : headersize)) > mtu) &&
-	    (skb_queue_len(queue) <= 1) &&
+	if ((((length + (skb ? skb->len : headersize)) > mtu) ||
+	     (skb && skb_is_gso(skb))) &&
 	    (sk->sk_protocol == IPPROTO_UDP) &&
 	    (rt->dst.dev->features & NETIF_F_UFO) && !dst_xfrm(&rt->dst) &&
-	    (sk->sk_type == SOCK_DGRAM) && !udp_get_no_check6_tx(sk))) {
+	    (sk->sk_type == SOCK_DGRAM) && !udp_get_no_check6_tx(sk)) {
 		err = ip6_ufo_append_data(sk, queue, getfrag, from, length,
 					  hh_len, fragheaderlen, exthdrlen,
 					  transhdrlen, mtu, flags, fl6);