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Date: Fri, 3 Nov 2023 10:18:01 +0100
From: Florian Westphal <fw@strlen.de>
To: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Florian Westphal <fw@strlen.de>,
	Pablo Neira Ayuso <pablo@netfilter.org>,
	Jozsef Kadlecsik <kadlec@netfilter.org>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	kernel-janitors@vger.kernel.org
Subject: Re: [PATCH net] netfilter: nf_tables: fix pointer math issue in
 nft_byteorder_eval()
Message-ID: <20231103091801.GA8035@breakpoint.cc>
References: <15fdceb5-2de5-4453-98b3-cfa9d486e8da@moroto.mountain>
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Dan Carpenter <dan.carpenter@linaro.org> wrote:
> The problem is in nft_byteorder_eval() where we are iterating through a
> loop and writing to dst[0], dst[1], dst[2] and so on...  On each
> iteration we are writing 8 bytes.  But dst[] is an array of u32 so each
> element only has space for 4 bytes.  That means that every iteration
> overwrites part of the previous element.
> 
> I spotted this bug while reviewing commit caf3ef7468f7 ("netfilter:
> nf_tables: prevent OOB access in nft_byteorder_eval") which is a related
> issue.  I think that the reason we have not detected this bug in testing
> is that most of time we only write one element.

LGTM, thanks Dan.  We will route this via nf.git.