ipv4: fix a bug in ping_err().

We should get 'type' and 'code' from the outer ICMP header.
Signed-off-by: NLi Wei <lw@cn.fujitsu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/ping.c

@@ -322,8 +322,8 @@ void ping_err(struct sk_buff *skb, u32 info)
 	struct iphdr *iph = (struct iphdr *)skb->data;
 	struct icmphdr *icmph = (struct icmphdr *)(skb->data+(iph->ihl<<2));
 	struct inet_sock *inet_sock;
-	int type = icmph->type;
-	int code = icmph->code;
+	int type = icmp_hdr(skb)->type;
+	int code = icmp_hdr(skb)->code;
 	struct net *net = dev_net(skb->dev);
 	struct sock *sk;
 	int harderr;