drm/vc4: Fix a couple error codes in vc4_cl_lookup_bos()

commit b2cdeb19 upstream.

If the allocation fails the current code returns success.  If
copy_from_user() fails it returns the number of bytes remaining instead
of -EFAULT.

Fixes: d5b1a78a ("drm/vc4: Add support for drawing 3D frames.")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/gpu/drm/vc4/vc4_gem.c

@@ -544,14 +544,15 @@ vc4_cl_lookup_bos(struct drm_device *dev,
 
 	handles = drm_malloc_ab(exec->bo_count, sizeof(uint32_t));
 	if (!handles) {
+		ret = -ENOMEM;
 		DRM_ERROR("Failed to allocate incoming GEM handles\n");
 		goto fail;
 	}
 
-	ret = copy_from_user(handles,
+	if (copy_from_user(handles,
 			   (void __user *)(uintptr_t)args->bo_handles,
-			     exec->bo_count * sizeof(uint32_t));
-	if (ret) {
+			   exec->bo_count * sizeof(uint32_t))) {
+		ret = -EFAULT;
 		DRM_ERROR("Failed to copy in GEM handles\n");
 		goto fail;
 	}