udp: with udp_segment release on error path

Failure __ip_append_data triggers udp_flush_pending_frames, but these
tests happen later. The skb must be freed directly.

Fixes: bec1f6f6 ("udp: generate gso with UDP_SEGMENT")
Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/udp.c

@@ -847,15 +847,23 @@ static int udp_send_skb(struct sk_buff *skb, struct flowi4 *fl4,
 		const int hlen = skb_network_header_len(skb) +
 				 sizeof(struct udphdr);
 
-		if (hlen + cork->gso_size > cork->fragsize)
+		if (hlen + cork->gso_size > cork->fragsize) {
+			kfree_skb(skb);
 			return -EINVAL;
-		if (skb->len > cork->gso_size * UDP_MAX_SEGMENTS)
+		}
+		if (skb->len > cork->gso_size * UDP_MAX_SEGMENTS) {
+			kfree_skb(skb);
 			return -EINVAL;
-		if (sk->sk_no_check_tx)
+		}
+		if (sk->sk_no_check_tx) {
+			kfree_skb(skb);
 			return -EINVAL;
+		}
 		if (skb->ip_summed != CHECKSUM_PARTIAL || is_udplite ||
-		    dst_xfrm(skb_dst(skb)))
+		    dst_xfrm(skb_dst(skb))) {
+			kfree_skb(skb);
 			return -EIO;
+		}
 
 		skb_shinfo(skb)->gso_size = cork->gso_size;
 		skb_shinfo(skb)->gso_type = SKB_GSO_UDP_L4;

net/ipv6/udp.c

@@ -1132,15 +1132,23 @@ static int udp_v6_send_skb(struct sk_buff *skb, struct flowi6 *fl6,
 		const int hlen = skb_network_header_len(skb) +
 				 sizeof(struct udphdr);
 
-		if (hlen + cork->gso_size > cork->fragsize)
+		if (hlen + cork->gso_size > cork->fragsize) {
+			kfree_skb(skb);
 			return -EINVAL;
-		if (skb->len > cork->gso_size * UDP_MAX_SEGMENTS)
+		}
+		if (skb->len > cork->gso_size * UDP_MAX_SEGMENTS) {
+			kfree_skb(skb);
 			return -EINVAL;
-		if (udp_sk(sk)->no_check6_tx)
+		}
+		if (udp_sk(sk)->no_check6_tx) {
+			kfree_skb(skb);
 			return -EINVAL;
+		}
 		if (skb->ip_summed != CHECKSUM_PARTIAL || is_udplite ||
-		    dst_xfrm(skb_dst(skb)))
+		    dst_xfrm(skb_dst(skb))) {
+			kfree_skb(skb);
 			return -EIO;
+		}
 
 		skb_shinfo(skb)->gso_size = cork->gso_size;
 		skb_shinfo(skb)->gso_type = SKB_GSO_UDP_L4;