[PATCH v2] mtd: rawnand: Prefer struct_size over open coded arithmetic

[PATCH v2] mtd: rawnand: Prefer struct_size over open coded arithmetic

[Erick Archer]

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 safer.

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]
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Erick Archer <erick.archer@gmx.com>
---
Changes in v2:
- Add the "Reviewed-by:" tag.
- Fix a spelling error in the commit message. Change "more safer" for
  "safer" (Uwe Kleine-König)
---
 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


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Re: [PATCH v2] mtd: rawnand: Prefer struct_size over open coded arithmetic

[Uwe Kleine-König]

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On Sun, Feb 11, 2024 at 10:16:33AM +0100, Erick Archer wrote:
> 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 safer.
> 
> 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]
> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
> Signed-off-by: Erick Archer <erick.archer@gmx.com>

Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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Re: [PATCH v2] mtd: rawnand: Prefer struct_size over open coded arithmetic

[AngeloGioacchino Del Regno]

Il 11/02/24 10:16, 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 safer.
> 
> 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]
> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
> Signed-off-by: Erick Archer <erick.archer@gmx.com>

Just noticed that there was a v2 already addressing the commit description issue.

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>



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Re: [PATCH v2] mtd: rawnand: Prefer struct_size over open coded arithmetic

[Matthias Brugger]

On 11/02/2024 10:16, Erick Archer wrote:
> 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 safer.
> 
> 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]
> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
> Signed-off-by: Erick Archer <erick.archer@gmx.com>

Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>

> ---
> Changes in v2:
> - Add the "Reviewed-by:" tag.
> - Fix a spelling error in the commit message. Change "more safer" for
>    "safer" (Uwe Kleine-König)
> ---
>   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
> 

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Re: [PATCH v2] mtd: rawnand: Prefer struct_size over open coded arithmetic

[Miquel Raynal]

On Sun, 2024-02-11 at 09:16:33 UTC, Erick Archer wrote:
> 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 safer.
> 
> 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]
> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
> Signed-off-by: Erick Archer <erick.archer@gmx.com>
> Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git nand/next, thanks.

Miquel

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