Re: [PATCH v4] drm/imagination: Fix parameter validation in pvr_fw_object_destroy()

[Alessio Belle]

On Tue, 2026-09-22 at 09:11 +0300, Alexandru Dadu wrote:
> Fix parameter validation to avoid possible NULL pointer dereference from
> pvr_fw_object_destroy() when handling allocation failures.
> 
> Sashiko report:
> If pvr_gem_object_create() fails in
> pvr_fw_object_create_and_map_common(), fw_obj->gem is explicitly set to
> NULL before jumping to the error cleanup path.
> The cleanup path then calls pvr_fw_object_destroy().
> 
> Reported-by: Sashiko <sashiko-bot@xxxxxxxxxx>
> Link: https://lore.kernel.org/dri-devel/20260810132202.3C16D1F000E9@xxxxxxxxxxxxxxx/
> Fixes: cc1aeedb98ad ("drm/imagination: Implement firmware infrastructure and META FW support")
> Signed-off-by: Alexandru Dadu <alexandru.dadu@xxxxxxxxxx>
> ---
> Changes in v4:
> - Move the structs declarations after the early return to fix V3.
> - Added kfree() to the early return path.
> - Link to v3: https://patch.msgid.link/20260922-fix-null-pointer-dereference-v3-1-f099763ed676@xxxxxxxxxx
> 
> Changes in v3:
> - Skimed the commit message removing redundant information.
> - Refactored the parameter validation to return early.
> - Link to v2: https://patch.msgid.link/20260903-fix-null-pointer-dereference-v2-1-138ff9b6f805@xxxxxxxxxx
> 
> Changes in v2:
> - Commit message and cover letter updates.
> - Link to v1: https://patch.msgid.link/20260812-fix-null-pointer-dereference-v1-1-f69b2ffe9520@xxxxxxxxxx
> 
> To: Alessio Belle <alessio.belle@xxxxxxxxxx>
> To: Luigi Santivetti <luigi.santivetti@xxxxxxxxxx>
> To: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> To: Maxime Ripard <mripard@xxxxxxxxxx>
> To: Thomas Zimmermann <tzimmermann@xxxxxxx>
> To: David Airlie <airlied@xxxxxxxxx>
> To: Simona Vetter <simona@xxxxxxxx>
> To: Donald Robson <donald.robson@xxxxxxxxxx>
> To: Sarah Walker <sarah.walker@xxxxxxxxxx>
> Cc: imagination@xxxxxxxxxxxxxxxxxxxxx
> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> ---
>  drivers/gpu/drm/imagination/pvr_fw.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/imagination/pvr_fw.c b/drivers/gpu/drm/imagination/pvr_fw.c
> index 850a3ec8e775..39d70f51f126 100644
> --- a/drivers/gpu/drm/imagination/pvr_fw.c
> +++ b/drivers/gpu/drm/imagination/pvr_fw.c
> @@ -1425,6 +1425,14 @@ pvr_fw_object_create_and_map_offset(struct pvr_device *pvr_dev,
>   */
>  void pvr_fw_object_destroy(struct pvr_fw_object *fw_obj)
>  {
> +	if (!fw_obj)
> +		return;
> +
> +	if (!fw_obj->gem) {
> +		kfree(fw_obj);
> +		return;
> +	}
> +
>  	struct pvr_gem_object *pvr_obj = fw_obj->gem;
>  	struct drm_gem_object *gem_obj = gem_from_pvr_gem(pvr_obj);
>  	struct pvr_device *pvr_dev = to_pvr_device(gem_obj->dev);

I have a preference for variable declarations at the top, then checks, then
assignments, but don't feel strongly about it, so:

Reviewed-by: Alessio Belle <alessio.belle@xxxxxxxxxx>

Thanks,
Alessio

> @@ -1439,8 +1447,7 @@ void pvr_fw_object_destroy(struct pvr_fw_object *fw_obj)
>  			return;
>  	}
>  
> -	if (fw_obj->gem)
> -		pvr_gem_object_put(fw_obj->gem);
> +	pvr_gem_object_put(fw_obj->gem);
>  
>  	kfree(fw_obj);
>  }
> 
> ---
> base-commit: bd4f284df04d76fd65e57141cb1e6e7a49e4c3cb
> change-id: 20260812-fix-null-pointer-dereference-2c891142d988
> 
> Best regards,
> --  
> Alexandru Dadu <alexandru.dadu@xxxxxxxxxx>
>