netdev - Re: [PATCH] ip6_tunnel: Clear IP6CB(skb)->frag_max_size in ip4ip6_tnl

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Date:   Thu, 27 Oct 2016 16:25:14 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     elicooper@....com
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH] ip6_tunnel: Clear IP6CB(skb)->frag_max_size in
 ip4ip6_tnl_xmit()

From: Eli Cooper <elicooper@....com>
Date: Mon, 24 Oct 2016 23:07:12 +0800

> diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
> index 202d16a..4110562 100644
> --- a/net/ipv6/ip6_tunnel.c
> +++ b/net/ipv6/ip6_tunnel.c
> @@ -1205,6 +1205,7 @@ ip4ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
>  	int err;
>  
>  	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
> +	IP6CB(skb)->frag_max_size = 0;
>  
>  	tproto = ACCESS_ONCE(t->parms.proto);
>  	if (tproto != IPPROTO_IPIP && tproto != 0)

This doesn't look right at all.

Either skb->cb is interpreted as IPCB() past this point, or
it is interpreted as IP6CB().

So pick which structure is used, and simply clear that specific
structure.