netdev - Re: [PATCH net v3 1/2] ip6_tunnel: Clear IP6CB in ip6tunnel

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Date:   Wed, 02 Nov 2016 15:19:21 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     elicooper@....com
Cc:     netdev@...r.kernel.org, shmulik.ladkani@...il.com,
        tom@...bertland.com
Subject: Re: [PATCH net v3 1/2] ip6_tunnel: Clear IP6CB in ip6tunnel_xmit()

From: Eli Cooper <elicooper@....com>
Date: Tue,  1 Nov 2016 23:45:12 +0800

> skb->cb may contain data from previous layers. In the observed scenario,
> the garbage data were misinterpreted as IP6CB(skb)->frag_max_size, so
> that small packets sent through the tunnel are mistakenly fragmented.
> 
> This patch unconditionally clears the control buffer in ip6tunnel_xmit(),
> which affects ip6_tunnel, ip6_udp_tunnel and ip6_gre. Currently none of
> these tunnels set IP6CB(skb)->flags, otherwise it needs to be done earlier.
> 
> Cc: stable@...r.kernel.org
> Signed-off-by: Eli Cooper <elicooper@....com>
> ---
> v3: moves to ip6tunnel_xmit() and clears IP6CB unconditionally
> v2: clears the whole IP6CB altogether and does it after encapsulation

Applied and queued up for -stable.