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Date: Tue, 10 Mar 2026 11:56:03 +0100
From: Pablo Neira Ayuso <pablo@netfilter.org>
To: Florian Westphal <fw@strlen.de>
Cc: netdev@vger.kernel.org, Paolo Abeni <pabeni@redhat.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, netfilter-devel@vger.kernel.org
Subject: Re: [PATCH net 00/10] netfilter: updates for net
Message-ID: <aa_4w9gXCkzQ06Nk@chamomile>
References: <20260309210845.15657-1-fw@strlen.de>
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In-Reply-To: <20260309210845.15657-1-fw@strlen.de>

Hi,

On Mon, Mar 09, 2026 at 10:08:35PM +0100, Florian Westphal wrote:
> 7-9) fix access bugs in the ctnetlink expectation handling.
>      Problem is that while RCU prevents the referenced nf_conn entry
>      from going way, nf_conn entries have an extension area that can
>      only be safely accessed if the cpu holds a reference to the
>      conntrack.  Else the extension area can be free'd at any time.
>      Fix is to grab references before the accesses happen.
>      These bugs are old, v3.10 resp. even pre-git days.
>      All fixes from Hyunwoo Kim.

I am not sure 7-9 are correct.

nfct_help() is accessed via exp->master in other existing paths,
I think these fixes are papering an underlying problem since the
typesafe rcu infrastructure was introduced in nf_conntrack.