Re: [PATCH] drm/solomon: Use kmalloc_array() instead of kmalloc()

Mehdi Ben Hadj Khelifa
2025-10-20T20:39:08Z

On 10/20/25 9:08 PM, Shuah Khan wrote:
> On 10/19/25 08:58, Mehdi Ben Hadj Khelifa wrote:
>> Replace kmalloc() with kmalloc_array() in several places to correctly
>> handle array allocations and benefit from built-in overflow checking.
>> This prevents potential integer overflows[1] when computing allocation
>> sizes from width, height, pitch, or page values.
>>
>> [1]:https://docs.kernel.org/process/deprecated.html
>
> Mu understanding is that this document lists deprecates APIs so people
> don't keep adding new ones.
>
> I didn't get the impression that we are supposed to go delete them from
> the kernel and cause a churn.
>
the document[1] specifically quotes the following:"
Dynamic 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. (One exception to this is literal values where the
compiler can warn if they might overflow. However, the preferred way in
these cases is to refactor the code as suggested below to avoid the
open-coded arithmetic.)"
Specifically mentionned the refactor of the code base in such cases
which is why i'm doing the patches in the first place.Also i'm trying
the best to send patches related to the issue where such issues of
overflow are present or to be consistent with the same API used within
the same subsystem.
[1]:https://docs.kernel.org/process/deprecated.html> How are you testing
these changes - do you have this hardware?
>
>>
I have a raspberrypi zero 2 wh that i'm using in combination with the
ssd1306 OLED panel via I2C to test it's rendering and it's working
properly by using modetest and seeing no regressions or warnings in dmesg.

Best Regards,
Mehdi Ben Hadj Khelifa

>> Signed-off-by: Mehdi Ben Hadj Khelifa <mehdi.benhadjkhelifa@gmail.com>
>> ---
>>   drivers/gpu/drm/solomon/ssd130x.c | 6 +++---
>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>
>
> thanks,
> -- Shuah