linux-hardening - Re: [PATCH] clk: hisilicon: Use devm_kcalloc() instead of devm

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Date: Mon, 22 Jan 2024 07:56:18 +0100
From: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To: Erick Archer <erick.archer@....com>
Cc: Michael Turquette <mturquette@...libre.com>, 
	Stephen Boyd <sboyd@...nel.org>, Conor Dooley <conor.dooley@...rochip.com>, 
	Heiko Stuebner <heiko@...ech.de>, Dinh Nguyen <dinguyen@...nel.org>, Rob Herring <robh@...nel.org>, 
	Nick Alcock <nick.alcock@...cle.com>, "Gustavo A. R. Silva" <gustavoars@...nel.org>, 
	linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] clk: hisilicon: Use devm_kcalloc() instead of
 devm_kzalloc()

On Sun, Jan 21, 2024 at 03:29:46PM +0100, Erick Archer wrote:
> As noted in the "Deprecated Interfaces, Language Features, Attributes,
> and Conventions" documentation [1], size calculations (especially
> multiplication) should not be performed in memory allocator (or similar)
> function arguments due to the risk of them overflowing. This could lead
> to values wrapping around and a smaller allocation being made than the
> caller was expecting. Using those allocations could lead to linear
> overflows of heap memory and other misbehaviors.
> 
> So, use the purpose specific devm_kcalloc() function instead of the
> argument size * count in the devm_kzalloc() function.
> 
> Link: https://www.kernel.org/doc/html/next/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [1]
> Link: https://github.com/KSPP/linux/issues/162
> Signed-off-by: Erick Archer <erick.archer@....com>
> ---
>  drivers/clk/hisilicon/clk-hi3559a.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/clk/hisilicon/clk-hi3559a.c b/drivers/clk/hisilicon/clk-hi3559a.c
> index ff4ca0edce06..da476f940326 100644
> --- a/drivers/clk/hisilicon/clk-hi3559a.c
> +++ b/drivers/clk/hisilicon/clk-hi3559a.c
> @@ -461,8 +461,7 @@ static void hisi_clk_register_pll(struct hi3559av100_pll_clock *clks,
>  	struct clk_init_data init;
>  	int i;
> 
> -	p_clk = devm_kzalloc(dev, sizeof(*p_clk) * nums, GFP_KERNEL);
> -
> +	p_clk = devm_kcalloc(dev, nums, sizeof(*p_clk), GFP_KERNEL);
>  	if (!p_clk)
>  		return;

Looks good,

Reviewed-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>

My first impulse was to ask why hisi_clk_register_pll doesn't return an
error if the allocation fails, but I guess that happens so early that no
sensible error handling is possible?

Best regards
Uwe

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

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