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Date: Wed, 13 Dec 2023 11:10:22 -0800
From: Kees Cook <keescook@chromium.org>
To: Jeff Johnson <quic_jjohnson@quicinc.com>
Cc: Kalle Valo <kvalo@kernel.org>,
	"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
	ath10k@lists.infradead.org, linux-wireless@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/6] wifi: ath10k: use flexible array in struct
 wmi_host_mem_chunks
Message-ID: <202312131110.F94BC3427@keescook>
References: <20231213-wmi_host_mem_chunks_flexarray-v1-0-92922d92fa2c@quicinc.com>
 <20231213-wmi_host_mem_chunks_flexarray-v1-1-92922d92fa2c@quicinc.com>
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In-Reply-To: <20231213-wmi_host_mem_chunks_flexarray-v1-1-92922d92fa2c@quicinc.com>

On Wed, Dec 13, 2023 at 09:06:39AM -0800, Jeff Johnson wrote:
> Currently struct wmi_host_mem_chunks defines:
> 	struct host_memory_chunk items[1];
> 
> Per the guidance in [1] this should be a flexible array. However there
> is a documented requirement:
> 	some fw revisions require at least 1 chunk regardless of count
> 
> To satisfy this requirement, follow the guidance from [2] and wrap the
> array in a union which contains both the flexible array and a single
> instance of the underlying struct. Since the footprint of the struct
> is unchanged, no additional driver changes are required.
> 
> No functional changes, compile tested only.
> 
> [1] https://docs.kernel.org/process/deprecated.html#zero-length-and-one-element-arrays
> [2] https://lore.kernel.org/linux-wireless/202308301529.AC90A9EF98@keescook/
> 
> Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>

This looks like the right approach here.

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook