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Date:   Mon, 3 Jul 2023 17:22:56 +0200
From:   Florian Westphal <fw@strlen.de>
To:     Florent Revest <revest@chromium.org>
Cc:     netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        bpf@vger.kernel.org, pablo@netfilter.org, kadlec@netfilter.org,
        fw@strlen.de, davem@davemloft.net, edumazet@google.com,
        kuba@kernel.org, pabeni@redhat.com, kpsingh@kernel.org,
        stable@vger.kernel.org
Subject: Re: [PATCH nf v2] netfilter: conntrack: Avoid nf_ct_helper_hash uses
 after free
Message-ID: <20230703152256.GC7043@breakpoint.cc>
References: <20230703145216.1096265-1-revest@chromium.org>
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Florent Revest <revest@chromium.org> wrote:
> If nf_conntrack_init_start() fails (for example due to a
> register_nf_conntrack_bpf() failure), the nf_conntrack_helper_fini()
> clean-up path frees the nf_ct_helper_hash map.
> 
> When built with NF_CONNTRACK=y, further netfilter modules (e.g:
> netfilter_conntrack_ftp) can still be loaded and call
> nf_conntrack_helpers_register(), independently of whether nf_conntrack
> initialized correctly. This accesses the nf_ct_helper_hash dangling
> pointer and causes a uaf, possibly leading to random memory corruption.
> 
> This patch guards nf_conntrack_helper_register() from accessing a freed
> or uninitialized nf_ct_helper_hash pointer and fixes possible
> uses-after-free when loading a conntrack module.

Reviewed-by: Florian Westphal <fw@strlen.de>