netdev - Re: [PATCH net] netfilter: nf_tables: fix pointer math issue in nft_byteorder

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Message-ID: <20240206111112.GD17626@breakpoint.cc>
Date: Tue, 6 Feb 2024 12:11:12 +0100
From: Florian Westphal <fw@...len.de>
To: Michal Kubecek <mkubecek@...e.cz>
Cc: Dan Carpenter <dan.carpenter@...aro.org>,
	Florian Westphal <fw@...len.de>,
	Pablo Neira Ayuso <pablo@...filter.org>,
	Jozsef Kadlecsik <kadlec@...filter.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,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org, andrea.mattiazzo@...e.com
Subject: Re: [PATCH net] netfilter: nf_tables: fix pointer math issue in
 nft_byteorder_eval()

Michal Kubecek <mkubecek@...e.cz> wrote:
> I stumbled upon this when the issue got a CVE id (sigh) and I share
> Andrea's (Cc-ed) concern that the fix is incomplete. While the fix,
> commit c301f0981fdd ("netfilter: nf_tables: fix pointer math issue in
> nft_byteorder_eval()") now, fixes the destination side, src is still
> a pointer to u32, i.e. we are reading 64-bit values with relative
> offsets which are multiples of 32 bits.
> 
> Shouldn't we fix this as well, e.g. like indicated below?

No, please remove multi-elem support instead, nothing uses this feature.