[Intel-gfx] [PATCH v2 2/3 drm: Check property/enum name length

[Daniel Vetter]

On Fri, Mar 02, 2018 at 04:03:00PM +0200, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Reject requests to add properties/enums with an overly long name.
> Previously we would have just silently truncated the string and exposed
> it userspace.
> 
> v2: drm_property_create() returns a pointer
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

While you're typing validation code, I noticed that drm_property_add_enum
allows you to overwrite the name of an existing enum value already added.
That sounds like something we never want to allow either.

Anyway, this is

Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

> ---
>  drivers/gpu/drm/drm_property.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_property.c b/drivers/gpu/drm/drm_property.c
> index fe8627fb7ae6..c37ac41125b5 100644
> --- a/drivers/gpu/drm/drm_property.c
> +++ b/drivers/gpu/drm/drm_property.c
> @@ -78,6 +78,9 @@ struct drm_property *drm_property_create(struct drm_device *dev, int flags,
>  	struct drm_property *property = NULL;
>  	int ret;
>  
> +	if (WARN_ON(strlen(name) >= DRM_PROP_NAME_LEN))
> +		return NULL;
> +
>  	property = kzalloc(sizeof(struct drm_property), GFP_KERNEL);
>  	if (!property)
>  		return NULL;
> @@ -372,6 +375,9 @@ int drm_property_add_enum(struct drm_property *property, int index,
>  {
>  	struct drm_property_enum *prop_enum;
>  
> +	if (WARN_ON(strlen(name) >= DRM_PROP_NAME_LEN))
> +		return -EINVAL;
> +
>  	if (!(drm_property_type_is(property, DRM_MODE_PROP_ENUM) ||
>  			drm_property_type_is(property, DRM_MODE_PROP_BITMASK)))
>  		return -EINVAL;
> -- 
> 2.16.1
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch