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

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Date: Sat, 20 Jan 2024 22:24:42 +0800
From: Hu Haowen <2023002089@...k.tyut.edu.cn>
To: Erick Archer <erick.archer@....com>, Alex Shi <alexs@...nel.org>,
 Yanteng Si <siyanteng@...ngson.cn>, Jonathan Corbet <corbet@....net>,
 "Gustavo A. R. Silva" <gustavoars@...nel.org>
Cc: linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-hardening@...r.kernel.org
Subject: Re: [PATCH] docs/zh_CN/power: Use kcalloc() instead of kzalloc()


在 2024/1/20 20:22, Erick Archer 写道:
> 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>
> ---
>   Documentation/translations/zh_CN/power/opp.rst | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/Documentation/translations/zh_CN/power/opp.rst b/Documentation/translations/zh_CN/power/opp.rst
> index 8d6e3f6f6202..7470fa2d4c43 100644
> --- a/Documentation/translations/zh_CN/power/opp.rst
> +++ b/Documentation/translations/zh_CN/power/opp.rst
> @@ -274,7 +274,7 @@ dev_pm_opp_get_opp_count
>   	 {
>   		/* 做一些事情 */
>   		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);


If the translated version is modified, I think the original file should
follow as well at Documentation/power/opp.rst line 308:

diff --git a/Documentation/power/opp.rst b/Documentation/power/opp.rst
index a7c03c470980..dca35018214a 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(sizeof(u32) * num_available, GFP_KERNEL);
                 /* populate the table in increasing order */
                 freq = 0;
                 while (!IS_ERR(opp = dev_pm_opp_find_freq_ceil(dev, 
&freq))) {

Thanks,
Hu Haowen


>   		/* 按升序填充表 */
>   		freq = 0;
>   		while (!IS_ERR(opp = dev_pm_opp_find_freq_ceil(dev, &freq))) {
> --
> 2.25.1
>
>
>