On Sun, 2017-06-04 at 14:43 +0800, Haishuang Yan wrote:
> Since iptunnel_pull_header() can call pskb_may_pull(),
> we must reload any pointer that was related to skb->head.
>
> Fixes: a09a4c8dd1ec ("tunnels: Remove encapsulation offloads on decap")
> Signed-off-by: Haishuang Yan <yanhaishu...@cmss.chinamobile.com>
> ---
> net/ipv6/sit.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
> index 61e5902..af832e7 100644
> --- a/net/ipv6/sit.c
> +++ b/net/ipv6/sit.c
> @@ -657,6 +657,7 @@ static int ipip6_rcv(struct sk_buff *skb)
> if (iptunnel_pull_header(skb, 0, htons(ETH_P_IPV6),
> !net_eq(tunnel->net, dev_net(tunnel->dev))))
> goto out;
> + iph = ip_hdr(skb);
>
> err = IP_ECN_decapsulate(iph, skb);
> if (unlikely(err)) {
This seems unnecessary.
By the time ipip6_rcv() is called, we already have the guarantee the
IPv4 header is in skb linear part.
Otherwise we could not use iph->saddr and iph->daddr in the call to
ipip6_tunnel_lookup()
Therefore, the pskb_may_pull() is a nop in this particular case.
