[IPV4] TCPMD5: Use memmove() instead of memcpy() because we have overlaps.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/tcp_ipv4.c

@@ -938,7 +938,7 @@ int tcp_v4_md5_do_del(struct sock *sk, __be32 addr)
 				tp->md5sig_info->alloced4 = 0;
 			} else if (tp->md5sig_info->entries4 != i) {
 				/* Need to do some manipulation */
-				memcpy(&tp->md5sig_info->keys4[i],
+				memmove(&tp->md5sig_info->keys4[i],
 					&tp->md5sig_info->keys4[i+1],
 					(tp->md5sig_info->entries4 - i) *
 					 sizeof(struct tcp4_md5sig_key));