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

[Ville Syrjälä]

On Tue, Mar 06, 2018 at 07:22:51PM +0100, Daniel Vetter wrote:
> 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 :-)

Hmm. Yeah, I guess that kind of a fail is fairly unlikely because the
defines won't be there. Would require the driver to basically pass in
utter garbage instead of just a bad combination of existing flags.

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

Thanks. Series pushed to drm-misc-next.

> >  
> >  /**
> > @@ -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
> > 
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

-- 
Ville Syrjälä
Intel OTC