Nouveau - Jun 2024 - [PATCH] drm/nouveau: fix null pointer dereference in nouveau_connector_get_modes

On Wed, 26 Jun 2024, Ma Ke <make24 at iscas.ac.cn>
wrote:
> In nouveau_connector_get_modes(), the return value of drm_mode_duplicate()
> is assigned to mode, which will lead to a possible NULL pointer
> dereference on failure of drm_mode_duplicate(). Add a check to avoid npd.
>
> Signed-off-by: Ma Ke <make24 at iscas.ac.cn>
> ---
>  drivers/gpu/drm/nouveau/nouveau_connector.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c
b/drivers/gpu/drm/nouveau/nouveau_connector.c
> index 856b3ef5edb8..010eed56b14d 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_connector.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
> @@ -1001,6 +1001,8 @@ nouveau_connector_get_modes(struct drm_connector
*connector)
>  		struct drm_display_mode *mode;
>  
>  		mode = drm_mode_duplicate(dev, nv_connector->native_mode);
> +		if (!mode)
> +			return -ENOMEM;
Do not return negative values from .get_modes().

BR,
Jani.
>  		drm_mode_probed_add(connector, mode);
>  		ret = 1;
>  	}
-- 
Jani Nikula, Intel

On 6/26/24 11:44, Jani Nikula wrote:
> On Wed, 26 Jun 2024, Ma Ke <make24 at iscas.ac.cn> wrote:
>> In nouveau_connector_get_modes(), the return value of
drm_mode_duplicate()
>> is assigned to mode, which will lead to a possible NULL pointer
>> dereference on failure of drm_mode_duplicate(). Add a check to avoid
npd.
>>
Please add a "Fixes" tag (also for your previous commits) and CC
stable.
>> Signed-off-by: Ma Ke <make24 at iscas.ac.cn>
>> ---
>>   drivers/gpu/drm/nouveau/nouveau_connector.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c
b/drivers/gpu/drm/nouveau/nouveau_connector.c
>> index 856b3ef5edb8..010eed56b14d 100644
>> --- a/drivers/gpu/drm/nouveau/nouveau_connector.c
>> +++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
>> @@ -1001,6 +1001,8 @@ nouveau_connector_get_modes(struct drm_connector
*connector)
>>   		struct drm_display_mode *mode;
>>   
>>   		mode = drm_mode_duplicate(dev, nv_connector->native_mode);
>> +		if (!mode)
>> +			return -ENOMEM;
> 
> Do not return negative values from .get_modes().
+1

https://elixir.bootlin.com/linux/latest/source/include/drm/drm_modeset_helper_vtables.h#L899
> 
> BR,
> Jani.
> 
>>   		drm_mode_probed_add(connector, mode);
>>   		ret = 1;
>>   	}
>