Re: [PATCH 4/7] drm: plane: Check source coordinates

[Jesse Barnes <jbarnes@virtuousgeek.org>]

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On Fri, 11 Nov 2011 19:18:52 +0200
Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:

> On Fri, Nov 11, 2011 at 08:24:18AM -0800, Jesse Barnes wrote:
> > On Fri, 11 Nov 2011 18:04:04 +0200
> > ville.syrjala@linux.intel.com wrote:
> > 
> > > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > 
> > > Make sure the source coordinates stay within the buffer.
> > > 
> > > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > ---
> > >  drivers/gpu/drm/drm_crtc.c |   23 +++++++++++++++++++++++
> > >  1 files changed, 23 insertions(+), 0 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> > > index 70f5747..098cc50 100644
> > > --- a/drivers/gpu/drm/drm_crtc.c
> > > +++ b/drivers/gpu/drm/drm_crtc.c
> > > @@ -1654,6 +1654,7 @@ int drm_mode_setplane(struct drm_device *dev, void *data,
> > >  	struct drm_crtc *crtc;
> > >  	struct drm_framebuffer *fb;
> > >  	int ret = 0;
> > > +	unsigned int fb_width, fb_height;
> > >  
> > >  	if (!drm_core_check_feature(dev, DRIVER_MODESET))
> > >  		return -EINVAL;
> > > @@ -1702,6 +1703,28 @@ int drm_mode_setplane(struct drm_device *dev, void *data,
> > >  	}
> > >  	fb = obj_to_fb(obj);
> > >  
> > > +	fb_width = fb->width << 16;
> > > +	fb_height = fb->height << 16;
> > > +
> > > +	/* Make sure source coordinates are inside the fb. */
> > > +	if (plane_req->src_w > fb_width ||
> > > +	    plane_req->src_x > fb_width - plane_req->src_w ||
> > > +	    plane_req->src_h > fb_height ||
> > > +	    plane_req->src_y > fb_height - plane_req->src_h) {
> > > +		DRM_DEBUG_KMS("Invalid source coordinates "
> > > +			      "%01u.%06ux%01u.%06u+%01u.%06u+%01u.%06u\n",
> > > +			      plane_req->src_w >> 16,
> > > +			      ((plane_req->src_w & 0xffff) * 15625) >> 10,
> > > +			      plane_req->src_h >> 16,
> > > +			      ((plane_req->src_h & 0xffff) * 15625) >> 10,
> > > +			      plane_req->src_x >> 16,
> > > +			      ((plane_req->src_x & 0xffff) * 15625) >> 10,
> > > +			      plane_req->src_y >> 16,
> > > +			      ((plane_req->src_y & 0xffff) * 15625) >> 10);
> > > +		ret = -EINVAL;
> > > +		goto out;
> > > +	}
> > > +
> > >  	ret = plane->funcs->update_plane(plane, crtc, fb,
> > >  					 plane_req->crtc_x, plane_req->crtc_y,
> > >  					 plane_req->crtc_w, plane_req->crtc_h,
> > 
> > Good sanity check (saves the drivers from having to do it), but I
> > wonder if we can use a better return value like ENOSPC or something to
> > make it easier for userspace to figure out.
> 
> Yeah, getting EINVAL for every kind of failure is rather annoying. The
> only issue I have with ENOSPC is the strerror() output. It doesn't
> exactly fit this use case. But if there's nothing better I'm OK with
> ENOSPC.

Yeah, dunno what's best.  Check out include/asm-generic/errno-base.h
and errno.h; maybe you'll find a better fit.

-- 
Jesse Barnes, Intel Open Source Technology Center

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