[PATCH 6/6] drm: Reject bad property flag combinations

[Daniel Vetter]

On Tue, Mar 06, 2018 at 06:48:49PM +0200, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Pimp drm_property_type_valid() to check for more fails with the
> property flags. Also make the check before adding the property,
> and bail out if things look bad.
> 
> Since we're now chekcing for more than the type let's also
> change the function name to drm_property_flags_valid().
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/drm_property.c | 29 +++++++++++++++++++++++------
>  1 file changed, 23 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_property.c b/drivers/gpu/drm/drm_property.c
> index 027a50e55e96..6ac6ee41a6a3 100644
> --- a/drivers/gpu/drm/drm_property.c
> +++ b/drivers/gpu/drm/drm_property.c
> @@ -50,11 +50,27 @@
>   * IOCTL and in the get/set property IOCTL.
>   */
>  
> -static bool drm_property_type_valid(struct drm_property *property)
> +static bool drm_property_flags_valid(u32 flags)
>  {
> -	if (property->flags & DRM_MODE_PROP_EXTENDED_TYPE)
> -		return !(property->flags & DRM_MODE_PROP_LEGACY_TYPE);
> -	return !!(property->flags & DRM_MODE_PROP_LEGACY_TYPE);
> +	u32 legacy_type = flags & DRM_MODE_PROP_LEGACY_TYPE;
> +	u32 ext_type = flags & DRM_MODE_PROP_EXTENDED_TYPE;
> +
> +	/* Reject undefined/deprecated flags */
> +	if (flags & ~(DRM_MODE_PROP_LEGACY_TYPE |
> +		      DRM_MODE_PROP_EXTENDED_TYPE |
> +		      DRM_MODE_PROP_IMMUTABLE |
> +		      DRM_MODE_PROP_ATOMIC))
> +		return false;
> +
> +	/* We want either a legacy type or an extended type, but not both */
> +	if (!legacy_type == !ext_type)
> +		return false;
> +
> +	/* Only one legacy type at a time please */
> +	if (legacy_type && !is_power_of_2(legacy_type))
> +		return false;
> +
> +	return true;
>  }

I think this catches everything. Well except not-yet-assigned
EXTENDED_TYPE defines, but really we can overdo this :-)

Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
>  
>  /**
> @@ -79,6 +95,9 @@ struct drm_property *drm_property_create(struct drm_device *dev,
>  	struct drm_property *property = NULL;
>  	int ret;
>  
> +	if (WARN_ON(!drm_property_flags_valid(flags)))
> +		return NULL;
> +
>  	if (WARN_ON(strlen(name) >= DRM_PROP_NAME_LEN))
>  		return NULL;
>  
> @@ -108,8 +127,6 @@ struct drm_property *drm_property_create(struct drm_device *dev,
>  
>  	list_add_tail(&property->head, &dev->mode_config.property_list);
>  
> -	WARN_ON(!drm_property_type_valid(property));
> -
>  	return property;
>  fail:
>  	kfree(property->values);
> -- 
> 2.16.1
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch