1 files changed, 31 insertions, 1 deletions

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 984050f35c61..01bea76e3891 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -60,10 +60,38 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff *
 {
 	struct dst_entry *dst = skb_dst(skb);
 	struct net_device *dev = dst->dev;
+	unsigned int hh_len = LL_RESERVED_SPACE(dev);
+	int delta = hh_len - skb_headroom(skb);
 	const struct in6_addr *nexthop;
 	struct neighbour *neigh;
 	int ret;
 
+	/* Be paranoid, rather than too clever. */
+	if (unlikely(delta > 0) && dev->header_ops) {
+		/* pskb_expand_head() might crash, if skb is shared */
+		if (skb_shared(skb)) {
+			struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC);
+
+			if (likely(nskb)) {
+				if (skb->sk)
+					skb_set_owner_w(skb, skb->sk);
+				consume_skb(skb);
+			} else {
+				kfree_skb(skb);
+			}
+			skb = nskb;
+		}
+		if (skb &&
+		    pskb_expand_head(skb, SKB_DATA_ALIGN(delta), 0, GFP_ATOMIC)) {
+			kfree_skb(skb);
+			skb = NULL;
+		}
+		if (!skb) {
+			IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTDISCARDS);
+			return -ENOMEM;
+		}
+	}
+
 	if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr)) {
 		struct inet6_dev *idev = ip6_dst_idev(skb_dst(skb));
 
@@ -479,7 +507,9 @@ int ip6_forward(struct sk_buff *skb)
 	if (skb_warn_if_lro(skb))
 		goto drop;
 
-	if (!xfrm6_policy_check(NULL, XFRM_POLICY_FWD, skb)) {
+	if (!net->ipv6.devconf_all->disable_policy &&
+	    !idev->cnf.disable_policy &&
+	    !xfrm6_policy_check(NULL, XFRM_POLICY_FWD, skb)) {
 		__IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
 		goto drop;
 	}