[PATCH 1/9] drm: Warn about negative sizes when calculating scale factor

[Ville Syrjälä]

On Tue, Jul 26, 2016 at 05:24:42PM +0100, Chris Wilson wrote:
> On Tue, Jul 26, 2016 at 07:06:56PM +0300, ville.syrjala at linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > 
> > Passing negative width/hight to scale factor calculations is not
> > legal. Let's WARN if that happens.
> 
> Does this get called with user controllable inputs?

User controllable to a degree. width/height can only ever be positive
though.

> A quick grep leads
> me to drm_primary_helper_update() which suggests no. Did I miss a
> potential user controllable WARN->panic?

I just landed in the BUG_ON in intel_sprite.c on account of a typo I
made in the user src/crtc coordinate -> drm_rect conversion. Should
probably replace the BUG_ON() with WARN_ON() in i915 as well...

-- 
Ville Syrjälä
Intel OTC