net: hns: bug fix about ping6

The current upstreaming code fails to ping other IPv6 net device, because
the enet receives the multicast packets with the src mac addr which is the
same as its mac addr. These packets need to be dropped.

Signed-off-by: Kejian Yan <yankejian@huawei.com>
Signed-off-by: Yisen Zhuang <Yisen.Zhuang@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/hisilicon/hns/hns_enet.c

@@ -564,6 +564,7 @@ static int hns_nic_poll_rx_skb(struct hns_nic_ring_data *ring_data,
 	struct sk_buff *skb;
 	struct hnae_desc *desc;
 	struct hnae_desc_cb *desc_cb;
+	struct ethhdr *eh;
 	unsigned char *va;
 	int bnum, length, i;
 	int pull_len;
@@ -670,6 +671,14 @@ out_bnum_err:
 		return -EFAULT;
 	}
 
+	/* filter out multicast pkt with the same src mac as this port */
+	eh = eth_hdr(skb);
+	if (unlikely(is_multicast_ether_addr(eh->h_dest) &&
+		     ether_addr_equal(ndev->dev_addr, eh->h_source))) {
+		dev_kfree_skb_any(skb);
+		return -EFAULT;
+	}
+
 	ring->stats.rx_pkts++;
 	ring->stats.rx_bytes += skb->len;