Re: [PATCH] platform/x86: wmi: Do not mix pages and kmalloc

[Kees Cook]

On Wed, Jun 20, 2018 at 4:37 PM, Darren Hart <dvhart@xxxxxxxxxxxxx> wrote:
> On Wed, Jun 20, 2018 at 02:31:41PM -0700, Kees Cook wrote:
>> The probe handler_data was being allocated with __get_free_pages()
>> for no reason I could find. The error path was using kfree(). Since
>
> v4 of Mario's series used kmalloc:
> https://patchwork.kernel.org/patch/9985827/
>
> This was changed in v10 to use __get_free_pages:
> https://patchwork.kernel.org/patch/10018023/
>
> But... I'm not finding the discussion that led to this change.... Mario,
> do you recall? Something about contiguous memory? We had a similar
> discussion on an earlier series:
>
> https://patchwork.kernel.org/patch/9975277/

FWIW, kmalloc gets you contiguous memory...

But if the reason is found and needs to stay, the probe error path's
kfree() needs to be fixed, and __GFP_COMP needs to be added to the
free page flags.

-Kees

-- 
Kees Cook
Pixel Security