[PATCH] docs/zh_CN/power: Use kcalloc() instead of kzalloc()

[PATCH] docs/zh_CN/power: Use kcalloc() instead of kzalloc()

[Erick Archer]

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

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

[Hu Haowen]

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@gmx.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
>
>
>

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

[Erick Archer]

Hi Hu and Jonathan,

On Sat, Jan 20, 2024 at 10:24:42PM +0800, Hu Haowen wrote:
>
> 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@gmx.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)))
> {

As you both suggested, this change should be made if the original file is
changed. Therefore, before this patch I already sent another one [1] that
made the proposed changes to the original file.

[1] https://lore.kernel.org/linux-hardening/20240120120527.3866-1-erick.archer@gmx.com/

But if you prefer, I can send just one patch with the two changes.

Best regards,
Erick

>
> 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
> >
> >
> >

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

[Jonathan Corbet]

Erick Archer <erick.archer@gmx.com> writes:

> 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@gmx.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);

Without addressing the validity of this change, as Hu says, we should
never change the translations without fixing the original as well -
otherwise they aren't really translations anymore.

Thanks,

jon