netdev - Re: [PATCH v2 net] xfrm: fix stack access out of bounds with CONFIG_XFRM_SUB

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Message-ID: <20170504103443.GU2649@secunet.com>
Date:   Thu, 4 May 2017 12:34:43 +0200
From:   Steffen Klassert <steffen.klassert@...unet.com>
To:     Sabrina Dubroca <sd@...asysnail.net>
CC:     <netdev@...r.kernel.org>, Herbert Xu <herbert@...dor.apana.org.au>
Subject: Re: [PATCH v2 net] xfrm: fix stack access out of bounds with
 CONFIG_XFRM_SUB_POLICY

On Wed, May 03, 2017 at 04:43:19PM +0200, Sabrina Dubroca wrote:
> When CONFIG_XFRM_SUB_POLICY=y, xfrm_dst stores a copy of the flowi for
> that dst. Unfortunately, the code that allocates and fills this copy
> doesn't care about what type of flowi (flowi, flowi4, flowi6) gets
> passed. In multiple code paths (from raw_sendmsg, from TCP when
> replying to a FIN, in vxlan, geneve, and gre), the flowi that gets
> passed to xfrm is actually an on-stack flowi4, so we end up reading
> stuff from the stack past the end of the flowi4 struct.
> 
> Since xfrm_dst->origin isn't used anywhere following commit
> ca116922afa8 ("xfrm: Eliminate "fl" and "pol" args to
> xfrm_bundle_ok()."), just get rid of it.  xfrm_dst->partner isn't used
> either, so get rid of that too.
> 
> Fixes: 9d6ec938019c ("ipv4: Use flowi4 in public route lookup interfaces.")
> Signed-off-by: Sabrina Dubroca <sd@...asysnail.net>

Applied to the ipsec tree, thanks Sabrina!