linux-hardening - Re: [PATCH] netfilter: x_tables: Use unsafe

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Date: Mon, 19 Feb 2024 17:17:46 +0000
From: Simon Horman <horms@...nel.org>
To: Kees Cook <keescook@...omium.org>
Cc: Pablo Neira Ayuso <pablo@...filter.org>,
	Jozsef Kadlecsik <kadlec@...filter.org>,
	Florian Westphal <fw@...len.de>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	"Gustavo A . R . Silva" <gustavo@...eddedor.com>,
	netfilter-devel@...r.kernel.org, coreteam@...filter.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-hardening@...r.kernel.org
Subject: Re: [PATCH] netfilter: x_tables: Use unsafe_memcpy() for 0-sized
 destination

On Fri, Feb 16, 2024 at 03:31:32PM -0800, Kees Cook wrote:
> The struct xt_entry_target fake flexible array has not be converted to a
> true flexible array, which is mainly blocked by it being both UAPI and
> used in the middle of other structures. In order to properly check for
> 0-sized destinations in memcpy(), an exception must be made for the one
> place where it is still a destination. Since memcpy() was already
> skipping checks for 0-sized destinations, using unsafe_memcpy() is no
> change in behavior.
> 
> Signed-off-by: Kees Cook <keescook@...omium.org>

Reviewed-by: Simon Horman <horms@...nel.org>