linux-kernel - Re: [PATCH] netfilter: ebtables: fix a NULL pointer dereference in ebt_do

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Message-ID: <YwELUWJw1qTatIiI@strlen.de>
Date:   Sat, 20 Aug 2022 18:26:57 +0200
From:   Florian Westphal <fw@...len.de>
To:     Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>
Cc:     syzkaller@...glegroups.com, george.kennedy@...cle.com,
        vegard.nossum@...cle.com, john.p.donnelly@...cle.com,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Jozsef Kadlecsik <kadlec@...filter.org>,
        Roopa Prabhu <roopa@...dia.com>,
        Nikolay Aleksandrov <razor@...ckwall.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        netfilter-devel@...r.kernel.org, coreteam@...filter.org,
        bridge@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] netfilter: ebtables: fix a NULL pointer dereference in
 ebt_do_table()

Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com> wrote:
> In ebt_do_table() function dereferencing 'private->hook_entry[hook]'
> can lead to NULL pointer dereference. So add a check to prevent that.

This looks incorrect, i.e. paperimg over the problem.

If hook_entry[hook] is NULL, how did this make it to the eval loop?

I guess ebtables lacks a sanity check on incoming ruleset?