udp: multicast RX should increment SNMP/sk_drops counter in allocation failures

When skb_clone() fails, we should increment sk_drops and SNMP counters.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 9d9072c..d73e917 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1335,12 +1335,22 @@
 {
 	unsigned int i;
 	struct sk_buff *skb1 = NULL;
+	struct sock *sk;
 
 	for (i = 0; i < count; i++) {
+		sk = stack[i];
 		if (likely(skb1 == NULL))
 			skb1 = (i == final) ? skb : skb_clone(skb, GFP_ATOMIC);
 
-		if (skb1 && udp_queue_rcv_skb(stack[i], skb1) <= 0)
+		if (!skb1) {
+			atomic_inc(&sk->sk_drops);
+			UDP_INC_STATS_BH(sock_net(sk), UDP_MIB_RCVBUFERRORS,
+					 IS_UDPLITE(sk));
+			UDP_INC_STATS_BH(sock_net(sk), UDP_MIB_INERRORS,
+					 IS_UDPLITE(sk));
+		}
+
+		if (skb1 && udp_queue_rcv_skb(sk, skb1) <= 0)
 			skb1 = NULL;
 	}
 	if (unlikely(skb1))