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

[ville.syrjala at linux.intel.com]

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>
---
 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