[Intel-gfx] [PATCH 09/10] drm/i915: Reject < 8 byte batches on 830/845

[Daniel Vetter]

On Mon, Dec 14, 2015 at 06:23:48PM +0200, ville.syrjala at linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> We use MI_BATCH_BUFFER on 830/845, which means we need to know
> the batch length. If the user passes a bad batch length (< 8)
> the results is most likely a GPU hang. Rejct such batches.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

Can't we just reject a 0 batch_len everywhere? Well fix up igt first ofc.
Slipping a 0 through really shouldn't be allowed.
-Daniel
> ---
>  drivers/gpu/drm/i915/intel_ringbuffer.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
> index 0c005a3dc57f..e878375be7eb 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> @@ -1825,6 +1825,9 @@ i830_dispatch_execbuffer(struct drm_i915_gem_request *req,
>  	u32 cs_offset = ring->scratch.gtt_offset;
>  	int ret;
>  
> +	if (len < 8)
> +		return -EINVAL;
> +
>  	ret = intel_ring_begin(req, 6);
>  	if (ret)
>  		return ret;
> -- 
> 2.4.10
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch