i915: return -EFAULT if copy_to_user fails

commit 9927a403 upstream.

copy_to_user returns the number of bytes remaining to be copied, but we
want to return a negative error code here.  These are returned to
userspace.
Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/gpu/drm/i915/i915_dma.c

@@ -683,8 +683,10 @@ static int i915_batchbuffer(struct drm_device *dev, void *data,
 		ret = copy_from_user(cliprects, batch->cliprects,
 				     batch->num_cliprects *
 				     sizeof(struct drm_clip_rect));
-		if (ret != 0)
+		if (ret != 0) {
+			ret = -EFAULT;
 			goto fail_free;
+		}
 	}
 
 	mutex_lock(&dev->struct_mutex);
@@ -725,8 +727,10 @@ static int i915_cmdbuffer(struct drm_device *dev, void *data,
 		return -ENOMEM;
 
 	ret = copy_from_user(batch_data, cmdbuf->buf, cmdbuf->sz);
-	if (ret != 0)
+	if (ret != 0) {
+		ret = -EFAULT;
 		goto fail_batch_free;
+	}
 
 	if (cmdbuf->num_cliprects) {
 		cliprects = kcalloc(cmdbuf->num_cliprects,
@@ -737,8 +741,10 @@ static int i915_cmdbuffer(struct drm_device *dev, void *data,
 		ret = copy_from_user(cliprects, cmdbuf->cliprects,
 				     cmdbuf->num_cliprects *
 				     sizeof(struct drm_clip_rect));
-		if (ret != 0)
+		if (ret != 0) {
+			ret = -EFAULT;
 			goto fail_clip_free;
+		}
 	}
 
 	mutex_lock(&dev->struct_mutex);