netdev - Re: [PATCH net] sit: Set skb->protocol properly in ipip6_tunnel

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Message-ID: <1480357935.18162.76.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Mon, 28 Nov 2016 10:32:15 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     David Miller <davem@...emloft.net>
Cc:     alexander.duyck@...il.com, sfr@...b.auug.org.au, elicooper@....com,
        netdev@...r.kernel.org
Subject: Re: [PATCH net] sit: Set skb->protocol properly in
 ipip6_tunnel_xmit()

On Mon, 2016-11-28 at 10:17 -0800, Eric Dumazet wrote:

> I was referring to Stephen bug report.
> 
> It appears that Eli changelog was not very precise, because his bug was
> because of XFRM being involved.
> 
> xfrm_output() -> xfrm_output_gso() -> skb_gso_segment()
> 
> So XFRM calls skb_gso_segment() before ip_output() or
> ip6_finish_output2() had a chance to change skb->protocol

So maybe the real fix would be to set skb->protocol at the right place,
before xfrm can be called, instead of chasing all skb producers ;)