ip_tunnel: clear IPCB in ip_tunnel_xmit() in case dst_link_failure() is called

commit a622260254ee48("ip_tunnel: fix kernel panic with icmp_dest_unreach")
clear IPCB in ip_tunnel_xmit()  , or else skb->cb[] may contain garbage from
GSO segmentation layer.

But commit 0e6fbc5b6c621("ip_tunnels: extend iptunnel_xmit()") refactor codes,
and it clear IPCB behind the dst_link_failure().

So clear IPCB in ip_tunnel_xmit() just like commti a622260254ee48("ip_tunnel:
fix kernel panic with icmp_dest_unreach").

Signed-off-by: Duan Jiong <duanj.fnst@cn.fujitsu.com>
---
 net/ipv4/ip_tunnel.c | 1 +
 1 file changed, 1 insertion(+)

On Mon, Jan 20, 2014 at 11:18 PM, Duan Jiong <duanj.fnst@cn.fujitsu.com> wrote:
>
> commit a622260254ee48("ip_tunnel: fix kernel panic with icmp_dest_unreach")
> clear IPCB in ip_tunnel_xmit()  , or else skb->cb[] may contain garbage from
> GSO segmentation layer.
>
> But commit 0e6fbc5b6c621("ip_tunnels: extend iptunnel_xmit()") refactor codes,
> and it clear IPCB behind the dst_link_failure().
>
ok.

> So clear IPCB in ip_tunnel_xmit() just like commti a622260254ee48("ip_tunnel:
> fix kernel panic with icmp_dest_unreach").
>
> Signed-off-by: Duan Jiong <duanj.fnst@cn.fujitsu.com>
> ---
>  net/ipv4/ip_tunnel.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
> index 90ff957..dda1e9a 100644
> --- a/net/ipv4/ip_tunnel.c
> +++ b/net/ipv4/ip_tunnel.c
> @@ -535,6 +535,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
>
>         inner_iph = (const struct iphdr *)skb_inner_network_header(skb);
>
> +       memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
>         dst = tnl_params->daddr;
>         if (dst == 0) {
>                 /* NBMA tunnel */

Can you clear IPCB in error path for dst_link_failure(). So that we do
not clear it twice in fast path.
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From: Pravin Shelar <pshelar@nicira.com>
Date: Tue, 21 Jan 2014 10:33:36 -0800

> Can you clear IPCB in error path for dst_link_failure(). So that we do
> not clear it twice in fast path.

Indeed, please add this memset() before the dst_link_failure() call.

Thanks.
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