[Intel-gfx] [PATCH 02/10] drm/uapi: Validate the mode flags/type

[Ville Syrjälä]

On Tue, Nov 14, 2017 at 06:42:06PM +0000, Chris Wilson wrote:
> Quoting Ville Syrjala (2017-11-14 18:32:50)
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > 
> > Currently userspace is allowed to feed in any king of garbage in the
> > high bits of the mode flags/type, as are drivers when probing modes.
> > Reject any mode with bogus flags/type.
> > 
> > Hopefully this won't break any current userspace...
> > 
> > Cc: Jose Abreu <Jose.Abreu at synopsys.com>
> > Cc: Adam Jackson <ajax at redhat.com>
> > Cc: Keith Packard <keithp at keithp.com>
> > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > ---
> >  drivers/gpu/drm/drm_modes.c |  4 ++++
> >  include/uapi/drm/drm_mode.h | 24 ++++++++++++++++++++++++
> >  2 files changed, 28 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
> > index 1a72883b836e..f99ba963fb3e 100644
> > --- a/drivers/gpu/drm/drm_modes.c
> > +++ b/drivers/gpu/drm/drm_modes.c
> > @@ -1036,6 +1036,10 @@ EXPORT_SYMBOL(drm_mode_equal_no_clocks_no_stereo);
> >  enum drm_mode_status
> >  drm_mode_validate_basic(const struct drm_display_mode *mode)
> >  {
> > +       if (mode->type & ~DRM_MODE_TYPE_ALL ||
> > +           mode->flags & ~DRM_MODE_FLAG_ALL)
> > +               return MODE_BAD;
> 
> I had to read this twice to realise they were different masks. (If the
> start and end of a word match expectations, the eye skips the middle.)
> Can we split this up into two separate ifs, so the reader doesn't fall
> into this trap :)

Sure, I can split that up.

-- 
Ville Syrjälä
Intel OTC