Received-SPF: pass (google.com: domain of linux-kernel+bounces-61216-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) client-ip=2604:1380:45d1:ec00::1;
Message-ID: <5cd419e6-2585-4f9e-b814-b928ebdb18f2@collabora.com>
Date: Mon, 12 Feb 2024 09:45:31 +0100
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH] mtd: rawnand: Prefer struct_size over open coded
 arithmetic
To: Erick Archer <erick.archer@gmx.com>,
 Miquel Raynal <miquel.raynal@bootlin.com>,
 Richard Weinberger <richard@nod.at>, Vignesh Raghavendra <vigneshr@ti.com>,
 Matthias Brugger <matthias.bgg@gmail.com>,
 Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
 Heiko Stuebner <heiko@sntech.de>, =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?=
 <philmd@linaro.org>, Rob Herring <robh@kernel.org>,
 Li Zetao <lizetao1@huawei.com>,
 =?UTF-8?Q?Uwe_Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de>,
 "Gustavo A. R. Silva" <gustavoars@kernel.org>,
 Kees Cook <keescook@chromium.org>
Cc: linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org,
 linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org,
 linux-hardening@vger.kernel.org
References: <20240210161619.12656-1-erick.archer@gmx.com>
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Content-Language: en-US
In-Reply-To: <20240210161619.12656-1-erick.archer@gmx.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit

Il 10/02/24 17:16, Erick Archer ha scritto:
> This is an effort to get rid of all multiplications from allocation
> functions in order to prevent integer overflows [1].
> 
> As the "chip" variable is a pointer to "struct mtk_nfc_nand_chip" and
> this structure ends in a flexible array:
> 
> struct mtk_nfc_nand_chip {
> 	[...]
> 	u8 sels[] __counted_by(nsels);
> };
> 
> the preferred way in the kernel is to use the struct_size() helper to
> do the arithmetic instead of the argument "size + count * size" in the
> devm_kzalloc() function.
> 
> This way, the code is more readable and more safer.

This way, the code is more readable and safer.

Apart from that,
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

> 
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [1]
> Link: https://github.com/KSPP/linux/issues/160 [2]
> Signed-off-by: Erick Archer <erick.archer@gmx.com>
> ---
>   drivers/mtd/nand/raw/mtk_nand.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/nand/raw/mtk_nand.c b/drivers/mtd/nand/raw/mtk_nand.c
> index 60198e33d2d5..17477bb2d48f 100644
> --- a/drivers/mtd/nand/raw/mtk_nand.c
> +++ b/drivers/mtd/nand/raw/mtk_nand.c
> @@ -1356,7 +1356,7 @@ static int mtk_nfc_nand_chip_init(struct device *dev, struct mtk_nfc *nfc,
>   		return -EINVAL;
>   	}
> 
> -	chip = devm_kzalloc(dev, sizeof(*chip) + nsels * sizeof(u8),
> +	chip = devm_kzalloc(dev, struct_size(chip, sels, nsels),
>   			    GFP_KERNEL);
>   	if (!chip)
>   		return -ENOMEM;
> --
> 2.25.1
>