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From:   Brian Norris <briannorris@chromium.org>
Date:   Mon, 9 Aug 2021 14:24:07 -0700
Message-ID: <CA+ASDXO+GbP_WWVdO0=Uavh036ZhZiziE8DwGRKP-ooofd2QVw@mail.gmail.com>
Subject: Re: [PATCH][next] mwifiex: usb: Replace one-element array with
 flexible-array member
To:     "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc:     Amitkumar Karwar <amitkarwar@gmail.com>,
        Ganapathi Bhat <ganapathi017@gmail.com>,
        Sharvari Harisangam <sharvari.harisangam@nxp.com>,
        Xinming Hu <huxinming820@gmail.com>,
        Kalle Valo <kvalo@codeaurora.org>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        linux-wireless <linux-wireless@vger.kernel.org>,
        "<netdev@vger.kernel.org>" <netdev@vger.kernel.org>,
        Linux Kernel <linux-kernel@vger.kernel.org>,
        linux-hardening@vger.kernel.org
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On Mon, Aug 9, 2021 at 2:08 PM Gustavo A. R. Silva
<gustavoars@kernel.org> wrote:
>
> There is a regular need in the kernel to provide a way to declare having
> a dynamically sized set of trailing elements in a structure. Kernel code
> should always use =E2=80=9Cflexible array members=E2=80=9D[1] for these c=
ases. The older
> style of one-element or zero-length arrays should no longer be used[2].
>
> This helps with the ongoing efforts to globally enable -Warray-bounds
> and get us closer to being able to tighten the FORTIFY_SOURCE routines
> on memcpy().
>
> This issue was found with the help of Coccinelle and audited and fixed,
> manually.
>
> [1] https://en.wikipedia.org/wiki/Flexible_array_member
> [2] https://www.kernel.org/doc/html/v5.10/process/deprecated.html#zero-le=
ngth-and-one-element-arrays
>
> Link: https://github.com/KSPP/linux/issues/79
> Link: https://github.com/KSPP/linux/issues/109
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

An important part of your patch rationale should include determining
that the 1-length wasn't actually important anywhere. I double checked
for you, and nobody seemed to be relying on 'sizeof struct fw_data' at
all, so this should be OK:

Reviewed-by: Brian Norris <briannorris@chromium.org>