linux-kernel - Re: [PATCH v2] netlink: Bounds-check struct nlmsgerr creation

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Message-ID: <5aad4860-b1c3-d78f-583d-26281626a49@netfilter.org>
Date:   Thu, 1 Sep 2022 09:06:03 +0200 (CEST)
From:   Jozsef Kadlecsik <kadlec@...filter.org>
To:     Kees Cook <keescook@...omium.org>
cc:     Jakub Kicinski <kuba@...nel.org>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Florian Westphal <fw@...len.de>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        syzbot <syzkaller@...glegroups.com>,
        netfilter-devel@...r.kernel.org, coreteam@...filter.org,
        netdev@...r.kernel.org, Petr Machata <petrm@...dia.com>,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH v2] netlink: Bounds-check struct nlmsgerr creation

Hi,

On Wed, 31 Aug 2022, Kees Cook wrote:

> For 32-bit systems, it might be possible to wrap lnmsgerr content
> lengths beyond SIZE_MAX. Explicitly test for all overflows, and mark the
> memcpy() as being unable to internally diagnose overflows.
> 
> This also excludes netlink from the coming runtime bounds check on
> memcpy(), since it's an unusual case of open-coded sizing and
> allocation. Avoid this future run-time warning:
> 
>   memcpy: detected field-spanning write (size 32) of single field "&errmsg->msg" at net/netlink/af_netlink.c:2447 (size 16)
> 
> Cc: Jakub Kicinski <kuba@...nel.org>
> Cc: Pablo Neira Ayuso <pablo@...filter.org>
> Cc: Jozsef Kadlecsik <kadlec@...filter.org>
> Cc: Florian Westphal <fw@...len.de>
> Cc: "David S. Miller" <davem@...emloft.net>
> Cc: Eric Dumazet <edumazet@...gle.com>
> Cc: Paolo Abeni <pabeni@...hat.com>
> Cc: syzbot <syzkaller@...glegroups.com>
> Cc: netfilter-devel@...r.kernel.org
> Cc: coreteam@...filter.org
> Cc: netdev@...r.kernel.org
> Signed-off-by: Kees Cook <keescook@...omium.org>
> ---
> v2: Rebased to -next
> v1: https://lore.kernel.org/lkml/20220901030610.1121299-3-keescook@chromium.org
> ---
>  net/netlink/af_netlink.c | 81 +++++++++++++++++++++++++---------------
>  1 file changed, 51 insertions(+), 30 deletions(-)

Could you add back the net/netfilter/ipset/ip_set_core.c part? Thanks!

Best regards,
Jozsef
-
E-mail  : kadlec@...ckhole.kfki.hu, kadlecsik.jozsef@...ner.hu
PGP key : https://wigner.hu/~kadlec/pgp_public_key.txt
Address : Wigner Research Centre for Physics
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