drm/ssd130x: Use kmalloc_array to prevent overflow of dynamic size calculation

[PATCH] drm/ssd130x: Use kmalloc_array to prevent overflow of dynamic size calculation

Posted by Bhanu Seshu Kumar Valluri 2 months, 2 weeks ago

Use kmalloc_array to avoid potential overflow during dynamic size calculation
inside kmalloc.

Signed-off-by: Bhanu Seshu Kumar Valluri <bhanuseshukumar@gmail.com>
---
 Note:
 Patch compiled successfully.
 No functionality change is intended.

 drivers/gpu/drm/solomon/ssd130x.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c
index eec43d1a5595..8368f0ffbe1e 100644
--- a/drivers/gpu/drm/solomon/ssd130x.c
+++ b/drivers/gpu/drm/solomon/ssd130x.c
@@ -1498,7 +1498,7 @@ static int ssd130x_crtc_atomic_check(struct drm_crtc *crtc,
 	if (ret)
 		return ret;
 
-	ssd130x_state->data_array = kmalloc(ssd130x->width * pages, GFP_KERNEL);
+	ssd130x_state->data_array = kmalloc_array(ssd130x->width, pages, GFP_KERNEL);
 	if (!ssd130x_state->data_array)
 		return -ENOMEM;
 
@@ -1519,7 +1519,7 @@ static int ssd132x_crtc_atomic_check(struct drm_crtc *crtc,
 	if (ret)
 		return ret;
 
-	ssd130x_state->data_array = kmalloc(columns * ssd130x->height, GFP_KERNEL);
+	ssd130x_state->data_array = kmalloc_array(columns, ssd130x->height, GFP_KERNEL);
 	if (!ssd130x_state->data_array)
 		return -ENOMEM;
 
@@ -1546,7 +1546,7 @@ static int ssd133x_crtc_atomic_check(struct drm_crtc *crtc,
 
 	pitch = drm_format_info_min_pitch(fi, 0, ssd130x->width);
 
-	ssd130x_state->data_array = kmalloc(pitch * ssd130x->height, GFP_KERNEL);
+	ssd130x_state->data_array = kmalloc_array(pitch, ssd130x->height, GFP_KERNEL);
 	if (!ssd130x_state->data_array)
 		return -ENOMEM;
 
-- 
2.34.1

Re: [PATCH] drm/ssd130x: Use kmalloc_array to prevent overflow of dynamic size calculation

Posted by Thomas Zimmermann 2 months, 2 weeks ago

Hi

Am 02.10.25 um 03:33 schrieb Bhanu Seshu Kumar Valluri:
> Use kmalloc_array to avoid potential overflow during dynamic size calculation
> inside kmalloc.
>
> Signed-off-by: Bhanu Seshu Kumar Valluri <bhanuseshukumar@gmail.com>
> ---
>   Note:
>   Patch compiled successfully.
>   No functionality change is intended.
>
>   drivers/gpu/drm/solomon/ssd130x.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c
> index eec43d1a5595..8368f0ffbe1e 100644
> --- a/drivers/gpu/drm/solomon/ssd130x.c
> +++ b/drivers/gpu/drm/solomon/ssd130x.c
> @@ -1498,7 +1498,7 @@ static int ssd130x_crtc_atomic_check(struct drm_crtc *crtc,
>   	if (ret)
>   		return ret;
>   
> -	ssd130x_state->data_array = kmalloc(ssd130x->width * pages, GFP_KERNEL);
> +	ssd130x_state->data_array = kmalloc_array(ssd130x->width, pages, GFP_KERNEL);

The first parameter is the number of elements. The second parameter is 
the size of an individual element. So the arguments should be swapped. 
Same for the other changes.

I know it's nitpicking, but who knows what it'll be good for. Fun fact 
is that even kmalloc_array mixes up both parameters internally.

Best regards
Thomas


>   	if (!ssd130x_state->data_array)
>   		return -ENOMEM;
>   
> @@ -1519,7 +1519,7 @@ static int ssd132x_crtc_atomic_check(struct drm_crtc *crtc,
>   	if (ret)
>   		return ret;
>   
> -	ssd130x_state->data_array = kmalloc(columns * ssd130x->height, GFP_KERNEL);
> +	ssd130x_state->data_array = kmalloc_array(columns, ssd130x->height, GFP_KERNEL);
>   	if (!ssd130x_state->data_array)
>   		return -ENOMEM;
>   
> @@ -1546,7 +1546,7 @@ static int ssd133x_crtc_atomic_check(struct drm_crtc *crtc,
>   
>   	pitch = drm_format_info_min_pitch(fi, 0, ssd130x->width);
>   
> -	ssd130x_state->data_array = kmalloc(pitch * ssd130x->height, GFP_KERNEL);
> +	ssd130x_state->data_array = kmalloc_array(pitch, ssd130x->height, GFP_KERNEL);
>   	if (!ssd130x_state->data_array)
>   		return -ENOMEM;
>   

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)

Re: [PATCH] drm/ssd130x: Use kmalloc_array to prevent overflow of dynamic size calculation

Posted by Javier Martinez Canillas 2 months, 2 weeks ago

Thomas Zimmermann <tzimmermann@suse.de> writes:

Hello Bhanu and Thomas,

> Hi
>
> Am 02.10.25 um 03:33 schrieb Bhanu Seshu Kumar Valluri:
>> Use kmalloc_array to avoid potential overflow during dynamic size calculation
>> inside kmalloc.
>>
>> Signed-off-by: Bhanu Seshu Kumar Valluri <bhanuseshukumar@gmail.com>
>> ---

The same patch was posted by another developer a couple of weeks ago
and is now queued already in the drm-misc-next branch:

https://cgit.freedesktop.org/drm/drm-misc/commit/?id=940dd88c5f5bdb1f3e19873a856a677ebada63a9

>>   Note:
>>   Patch compiled successfully.
>>   No functionality change is intended.
>>
>>   drivers/gpu/drm/solomon/ssd130x.c | 6 +++---
>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c
>> index eec43d1a5595..8368f0ffbe1e 100644
>> --- a/drivers/gpu/drm/solomon/ssd130x.c
>> +++ b/drivers/gpu/drm/solomon/ssd130x.c
>> @@ -1498,7 +1498,7 @@ static int ssd130x_crtc_atomic_check(struct drm_crtc *crtc,
>>   	if (ret)
>>   		return ret;
>>   
>> -	ssd130x_state->data_array = kmalloc(ssd130x->width * pages, GFP_KERNEL);
>> +	ssd130x_state->data_array = kmalloc_array(ssd130x->width, pages, GFP_KERNEL);
>
> The first parameter is the number of elements. The second parameter is 
> the size of an individual element. So the arguments should be swapped. 
> Same for the other changes.
>
> I know it's nitpicking, but who knows what it'll be good for. Fun fact 
> is that even kmalloc_array mixes up both parameters internally.
>

You are right. I didn't notice this subtlety when reviewing mentioned
patch that pushed to drm-misc-next.

> Best regards
> Thomas
>
>

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat