linux-kernel - Re: KASAN: stack-out-of-bounds Read in xfrm_state

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Message-ID: <20171115113656.GU11292@secunet.com>
Date:   Wed, 15 Nov 2017 12:36:56 +0100
From:   Steffen Klassert <steffen.klassert@...unet.com>
To:     Florian Westphal <fw@...len.de>
CC:     syzbot 
        <bot+19b21aa652248382e2b8cbb81fa1cdc03b4bda01@...kaller.appspotmail.com>,
        <davem@...emloft.net>, <herbert@...dor.apana.org.au>,
        <linux-kernel@...r.kernel.org>, <netdev@...r.kernel.org>,
        <syzkaller-bugs@...glegroups.com>, <thomas.egerer@...unet.com>
Subject: Re: KASAN: stack-out-of-bounds Read in xfrm_state_find (2)

On Mon, Nov 06, 2017 at 11:16:46AM +0100, Steffen Klassert wrote:
> 
> Subject: [PATCH ipsec] xfrm: Fix stack-out-of-bounds read in xfrm_state_find.
> 
> When we do tunnel or beet mode, we pass saddr and daddr from the
> template to xfrm_state_find(), this is ok. On transport mode,
> we pass the addresses from the flowi, assuming that the IP
> addresses (and address family) don't change during transformation.
> This assumption is wrong in the IPv4 mapped IPv6 case, packet
> is IPv4 and template is IPv6. Fix this by using the addresses
> from the template unconditionally.
> 
> Signed-off-by: Steffen Klassert <steffen.klassert@...unet.com>

I had to revert this, it broke transport mode when the policy
template has no src and dst addresses configured. I'll come up
with some other fix, probably don't do policy/flow maching
when a socket policies address family does not match the
flow address family. This should hopefully fix this whole
class of IPv4 mapped IPv6 with socket policy bugs.