Re: [PATCH net-next 5/5] ipv6: RFC 4884 partial support for SIT/GRE tunnels

On Sat, 2016-06-18 at 20:54 -0700, David Miller wrote:

From: Eric Dumazet <edumazet@google.com>
Date: Sat, 18 Jun 2016 16:26:40 -0700

quoted

@@ -588,12 +594,26 @@ int ip6_err_gen_icmpv6_unreach(struct sk_buff *skb, int nhs, int type)
 		skb2->dev = rt->dst.dev;
 
 	ipv6_addr_set_v4mapped(ip_hdr(skb)->saddr, &temp_saddr);
+
+	if (data_len) {
+		/* RFC 4884 (partial) support :
+		 * insert 0 padding at the end, before the extensions
+		 */
+		__skb_push(skb2, nhs);
+		skb_reset_network_header(skb2);
+		memcpy(skb2->data, skb2->data + nhs, data_len - nhs);

Since this is overlapping, it really need to use memmove() instead of
memcpy().

Interesting, I always thought memcpy(dest, src, xxx) was ok if src >
dest