Re: [PATCH] drm/i915/gvt/fb_decoder: Fix out-of-bounds read

[Gustavo A. R. Silva]

Hi Zhenyu,

Quoting Zhenyu Wang <zhenyuw@xxxxxxxxxxxxxxx>:

> On 2017.12.09 00:37:59 -0600, Gustavo A. R. Silva wrote:
> > In case function skl_format_to_drm returns -EINVAL, fmt turns into a huge
> > number as fmt is of type u32, hence there is an out-of-bounds read when
> > using fmt as an index for array skl_pixel_formats at line 225:
> > plane->bpp = skl_pixel_formats[fmt].bpp;
> >
> > Fix this by comparing the value returned by function skl_format_to_drm
> > against the size of array skl_pixel_formats, so in case it is greater than
> > or equal to the number of items contained in skl_pixel_formats, print an
> > error message and return -EINVAL.
> >
> > Addresses-Coverity-ID: 1462495
> > Addresses-Coverity-ID: 1462502 ("Out-of-bounds read")
> > Fixes: 9f31d1063b43 ("drm/i915/gvt: Add framebuffer decoder support")
> > Signed-off-by: Gustavo A. R. Silva <garsilva@xxxxxxxxxxxxxx>
> > ---
> >  drivers/gpu/drm/i915/gvt/fb_decoder.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/gvt/fb_decoder.c  
> > b/drivers/gpu/drm/i915/gvt/fb_decoder.c
> > index 72f4217..aed578b 100644
> > --- a/drivers/gpu/drm/i915/gvt/fb_decoder.c
> > +++ b/drivers/gpu/drm/i915/gvt/fb_decoder.c
> > @@ -222,6 +222,12 @@ int intel_vgpu_decode_primary_plane(struct  
> > intel_vgpu *vgpu,
> >  			val & PLANE_CTL_ORDER_RGBX,
> >  			val & PLANE_CTL_ALPHA_MASK,
> >  			val & PLANE_CTL_YUV422_ORDER_MASK);
> > +
> > +		if (fmt >= ARRAY_SIZE(skl_pixel_formats)) {
> > +			gvt_vgpu_err("Out-of-bounds pixel format index\n");
> > +			return -EINVAL;
> > +		}
> > +
> >  		plane->bpp = skl_pixel_formats[fmt].bpp;
> >  		plane->drm_format = skl_pixel_formats[fmt].drm_format;
> >  	} else {
> > --
>
> Applied this, thanks!

Glad to help. :)

Thanks
--
Gustavo A. R. Silva