diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c index 501630e3f1b6..84ba9ad00135 100644 --- a/net/ipv6/ip6_gre.c +++ b/net/ipv6/ip6_gre.c @@ -1383,9 +1383,16 @@ static int ip6gre_header(struct sk_buff *skb, struct net_device *dev, { struct ip6_tnl *t = netdev_priv(dev); struct ipv6hdr *ipv6h; + int needed; __be16 *p; - ipv6h = skb_push(skb, t->hlen + sizeof(*ipv6h)); + needed = t->hlen + sizeof(*ipv6h); + if (skb_headroom(skb) < needed && + pskb_expand_head(skb, HH_DATA_ALIGN(needed - skb_headroom(skb)), + 0, GFP_ATOMIC)) + return -needed; + + ipv6h = skb_push(skb, needed); ip6_flow_hdr(ipv6h, 0, ip6_make_flowlabel(dev_net(dev), skb, t->fl.u.ip6.flowlabel, true, &t->fl.u.ip6));