[Intel-gfx] [RFC 04/44] drm/i915: Fix null pointer dereference in error capture

[John.C.Harrison at Intel.com]

From: John Harrison <John.C.Harrison at Intel.com>

The i915_gem_record_rings() code was unconditionally querying and saving state
for the batch_obj of a request structure. This is not necessarily set. Thus a
null pointer dereference can occur.
---
 drivers/gpu/drm/i915/i915_gpu_error.c |   13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index 87ec60e..0738f21 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -902,12 +902,13 @@ static void i915_gem_record_rings(struct drm_device *dev,
 			 * as the simplest method to avoid being overwritten
 			 * by userspace.
 			 */
-			error->ring[i].batchbuffer =
-				i915_error_object_create(dev_priv,
-							 request->batch_obj,
-							 request->ctx ?
-							 request->ctx->vm :
-							 &dev_priv->gtt.base);
+			if(request->batch_obj)
+				error->ring[i].batchbuffer =
+					i915_error_object_create(dev_priv,
+								 request->batch_obj,
+								 request->ctx ?
+								 request->ctx->vm :
+								 &dev_priv->gtt.base);
 
 			if (HAS_BROKEN_CS_TLB(dev_priv->dev) &&
 			    ring->scratch.obj)
-- 
1.7.9.5