Re: [Intel-gfx] [PATCH] drm/i915: Validate execbuffer start/length arguments against the target bo

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Fri, Nov 20, 2015 at 03:11:04PM +0000, Chris Wilson wrote:
> The offset within and the length of the command sequence to execute are
> supplied by the user with respect to the batch buffer. We should be
> validating that region is wholly contained within the batch buffer;
> make it so.
> 
> Reported-by: Ville Syrj�l� <ville.syrjala@linux.intel.com>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: stable@vger.kernel.org
> ---
>  drivers/gpu/drm/i915/i915_gem_execbuffer.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> index a4c243cec4aa..e38284c1b89f 100644
> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> @@ -1462,6 +1462,13 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
>  	/* take note of the batch buffer before we might reorder the lists */
>  	batch_obj = eb_get_batch(eb);
>  
> +	if (args->batch_len > batch_obj->base.size ||
> +	    args->batch_start_offset > batch_obj->base.size - args->batch_len) {

lgtm. No possibility of overflow doing it that way.

Reviewed-by: Ville Syrj�l� <ville.syrjala@linux.intel.com>

> +		DRM_DEBUG("Attempting to execute commands from beyond the bounds of the batch object\n");
> +		ret = -EINVAL;
> +		goto err;
> +	}
> +
>  	/* Move the objects en-masse into the GTT, evicting if necessary. */
>  	need_relocs = (args->flags & I915_EXEC_NO_RELOC) == 0;
>  	ret = i915_gem_execbuffer_reserve(ring, &eb->vmas, ctx, &need_relocs);
> -- 
> 2.6.2
> 
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-- 
Ville Syrj�l�
Intel OTC