Re: [PATCH 5/7] drm: plane: Check crtc coodrinates against integer overflows in setplane ioctl

[Jesse Barnes <jbarnes@virtuousgeek.org>]

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On Fri, 11 Nov 2011 18:04:05 +0200
ville.syrjala@linux.intel.com wrote:

> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> Help drivers a little by guaranteeing that crtc_x+crtc_w and
> crtc_y+crtc_h don't overflow.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/drm_crtc.c |   12 ++++++++++++
>  1 files changed, 12 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> index 098cc50..2410a9a 100644
> --- a/drivers/gpu/drm/drm_crtc.c
> +++ b/drivers/gpu/drm/drm_crtc.c
> @@ -1725,6 +1725,18 @@ int drm_mode_setplane(struct drm_device *dev, void *data,
>  		goto out;
>  	}
>  
> +	/* Give drivers some help against integer overflows */
> +	if (plane_req->crtc_w > INT_MAX ||
> +	    plane_req->crtc_x > INT_MAX - (int32_t) plane_req->crtc_w ||
> +	    plane_req->crtc_h > INT_MAX ||
> +	    plane_req->crtc_y > INT_MAX - (int32_t) plane_req->crtc_h) {
> +		DRM_DEBUG_KMS("Invalid CRTC coordinates %ux%u+%d+%d\n",
> +			      plane_req->crtc_w, plane_req->crtc_h,
> +			      plane_req->crtc_x, plane_req->crtc_y);
> +		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,

Not sure this helps much in practice, since the drivers will have to
validate the target CRTC rect against the actual pipe dimensions anyway.

But it doesn't hurt either, so:
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>

-- 
Jesse Barnes, Intel Open Source Technology Center

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