netdev - Re: [PATCH v3] tunnel: Clear IPCB(skb)->opt before dst_link

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Message-Id: <20160223.191221.211549664974307758.davem@davemloft.net>
Date:	Tue, 23 Feb 2016 19:12:21 -0500 (EST)
From:	David Miller <davem@...emloft.net>
To:	bernie.harris@...iedtelesis.co.nz
Cc:	netdev@...r.kernel.org, kuznet@....inr.ac.ru,
	stable@...r.kernel.org
Subject: Re: [PATCH v3] tunnel: Clear IPCB(skb)->opt before
 dst_link_failure called

From: Bernie Harris <bernie.harris@...iedtelesis.co.nz>
Date: Mon, 22 Feb 2016 12:58:05 +1300

> IPCB may contain data from previous layers (in the observed case the
> qdisc layer). In the observed scenario, the data was misinterpreted as
> ip header options, which later caused the ihl to be set to an invalid
> value (<5). This resulted in an infinite loop in the mips implementation
> of ip_fast_csum.
> 
> This patch clears IPCB(skb)->opt before dst_link_failure can be called for
> various types of tunnels. This change only applies to encapsulated ipv4
> packets.
> 
> The code introduced in 11c21a30 which clears all of IPCB has been removed
> to be consistent with these changes, and instead the opt field is cleared
> unconditionally in ip_tunnel_xmit. The change in ip_tunnel_xmit applies to
> SIT, GRE, and IPIP tunnels.
> 
> The relevant vti, l2tp, and pptp functions already contain similar code for
> clearing the IPCB.
> 
> Signed-off-by: Bernie Harris <bernie.harris@...iedtelesis.co.nz>

Applied and queued up for -stable, thanks!