udp: Fix the SNMP counter of UDP_MIB_INERRORS

UDP packets received in udpv6_recvmsg() are not only IPv6 UDP packets, but
also have IPv4 UDP packets, so when do the counter of UDP_MIB_INERRORS in
udpv6_recvmsg(), we should check whether the packet is a IPv6 UDP packet
or a IPv4 UDP packet.

Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/udp.c

@@ -236,8 +236,14 @@ int udpv6_recvmsg(struct kiocb *iocb, struct sock *sk,
 
 csum_copy_err:
 	lock_sock(sk);
-	if (!skb_kill_datagram(sk, skb, flags))
-		UDP6_INC_STATS_USER(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
+	if (!skb_kill_datagram(sk, skb, flags)) {
+		if (is_udp4)
+			UDP_INC_STATS_USER(sock_net(sk),
+					UDP_MIB_INERRORS, is_udplite);
+		else
+			UDP6_INC_STATS_USER(sock_net(sk),
+					UDP_MIB_INERRORS, is_udplite);
+	}
 	release_sock(sk);
 
 	if (flags & MSG_DONTWAIT)