drm: Return EINVAL on duplicate objects in execbuffer object list

If userspace passes an object list with the same object appearing more
than once, we end up hitting the BUG_ON() in
i915_gem_object_set_to_gpu_domain() as it gets called a second time
for the same object.

Signed-off-by: Kristian Høgsberg <krh@redhat.com>
Signed-off-by: Eric Anholt <eric@anholt.net>

2 files changed, 22 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 17fa40858d26..9186d43be011 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -457,6 +457,12 @@ struct drm_i915_gem_object {
 
         /** for phy allocated objects */
         struct drm_i915_gem_phys_object *phys_obj;
+
+        /**
+         * Used for checking the object doesn't appear more than once
+         * in an execbuffer object list.
+         */
+        int in_execbuffer;
 };
 
 /**
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 85685bfd12da..7bdcc752f139 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2469,6 +2469,7 @@ i915_gem_execbuffer(struct drm_device *dev, void *data,
         struct drm_i915_gem_exec_object *exec_list = NULL;
         struct drm_gem_object **object_list = NULL;
         struct drm_gem_object *batch_obj;
+        struct drm_i915_gem_object *obj_priv;
         int ret, i, pinned = 0;
         uint64_t exec_offset;
         uint32_t seqno, flush_domains;
@@ -2533,6 +2534,15 @@ i915_gem_execbuffer(struct drm_device *dev, void *data,
                         ret = -EBADF;
                         goto err;
                 }
+
+                obj_priv = object_list[i]->driver_private;
+                if (obj_priv->in_execbuffer) {
+                        DRM_ERROR("Object %p appears more than once in object list\n",
+                                   object_list[i]);
+                        ret = -EBADF;
+                        goto err;
+                }
+                obj_priv->in_execbuffer = true;
         }
 
         /* Pin and relocate */
@@ -2674,8 +2684,13 @@ err:
         for (i = 0; i < pinned; i++)
                 i915_gem_object_unpin(object_list[i]);
 
-        for (i = 0; i < args->buffer_count; i++)
+        for (i = 0; i < args->buffer_count; i++) {
+                if (object_list[i]) {
+                        obj_priv = object_list[i]->driver_private;
+                        obj_priv->in_execbuffer = false;
+                }
                 drm_gem_object_unreference(object_list[i]);
+        }
 
         mutex_unlock(&dev->struct_mutex);