Revert "ipv6: prevent speculative execution"

CVE-2017-5753 (revert embargoed)
CVE-2017-5715 (revert embargoed)

This reverts commit 904c6712.
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

net/ipv6/raw.c

@@ -717,7 +717,6 @@ static int raw6_getfrag(void *from, char *to, int offset, int len, int odd,
 	if (offset < rfv->hlen) {
 		int copy = min(rfv->hlen - offset, len);
 
-		gmb();
 		if (skb->ip_summed == CHECKSUM_PARTIAL)
 			memcpy(to, rfv->c + offset, copy);
 		else