linux-kernel - Re: [PATCH] Documentation: power: Use kcalloc() instead of kzalloc()

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Date: Sun, 21 Jan 2024 12:44:31 +0100
From: Erick Archer <erick.archer@....com>
To: Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
	Stephen Boyd <sboyd@...nel.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
	"Gustavo A. R. Silva" <gustavoars@...nel.org>
Cc: Erick Archer <erick.archer@....com>, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] Documentation: power: Use kcalloc() instead of kzalloc()

On Sat, Jan 20, 2024 at 01:05:27PM +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, in the example code use the purpose specific kcalloc() function
> instead of the argument size * count in the 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>

Hi,

Drop this patch as a new version has been sent to change at the
same time the translations.

Thanks,
Erick

> ---
>  Documentation/power/opp.rst | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/Documentation/power/opp.rst b/Documentation/power/opp.rst
> index a7c03c470980..1b7f1d854f14 100644
> --- a/Documentation/power/opp.rst
> +++ b/Documentation/power/opp.rst
> @@ -305,7 +305,7 @@ dev_pm_opp_get_opp_count
>  	 {
>  		/* Do things */
>  		num_available = dev_pm_opp_get_opp_count(dev);
> -		speeds = kzalloc(sizeof(u32) * num_available, GFP_KERNEL);
> +		speeds = kcalloc(num_available, sizeof(u32), GFP_KERNEL);
>  		/* populate the table in increasing order */
>  		freq = 0;
>  		while (!IS_ERR(opp = dev_pm_opp_find_freq_ceil(dev, &freq))) {
> --
> 2.25.1
>