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

[Zhenyu Wang]

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 at embeddedor.com>
> ---
>  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!

-- 
Open Source Technology Center, Intel ltd.

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