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Date: Tue, 30 Jun 2026 07:16:48 +0200
From: Florian Westphal <fw@strlen.de>
To: Zhixing Chen <running910@gmail.com>
Cc: Pablo Neira Ayuso <pablo@netfilter.org>, Phil Sutter <phil@nwl.cc>,
	netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
	netdev@vger.kernel.org
Subject: Re: [PATCH nf] netfilter: ip6t_ah: validate AH header length
Message-ID: <akNRQFx9fmi2DK0w@strlen.de>
References: <20260618125848.93550-1-running910@gmail.com>
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In-Reply-To: <20260618125848.93550-1-running910@gmail.com>

Zhixing Chen <running910@gmail.com> wrote:
> ip6t_ah checks that the fixed AH header is present, then uses hdrlen to
> derive the advertised AH header length for matching.
> 
> Return false if the skb does not contain the advertised AH header length.
> This avoids matching AH headers whose advertised length is not present in
> the skb.
> 
> Signed-off-by: Zhixing Chen <running910@gmail.com>
> ---
> 
> I noticed ip6t_hbh and ip6t_rt already do this advertised-length check
> for their IPv6 extension headers, so this keeps ip6t_ah in line with
> those matches.

Could you make a v2 that addresses

https://sashiko.dev/#/patchset/20260618125848.93550-1-running910%40gmail.com
?

We should not return false in matches for malformed packets without
also setting ->hotdrop = true.