drm_gem.c

int drm_dumb_set_label_ioctl(struct drm_device *dev,
				void *data, struct drm_file *file_priv)
{
	char *label;
	struct drm_dumb_set_label_object *args = data;
	int ret = 0;

	if (!dev->driver->label)
		return -EOPNOTSUPP;

	if (!args->len || !args->name)
		label = NULL;
	else
		label = strndup_user(u64_to_user_ptr(args->name), args->len);

	if (IS_ERR(label)) {
		ret = PTR_ERR(label);
		return ret;
	}

	ret = dev->driver->label(dev, file_priv, args->handle, label);

err:
	kfree(label);
	return ret;
}

I'd rather have

if (!args->len)
	label = NULL;
else if (args->len && args->name)
	label = strndup_user(u64_to_user_ptr(args->name), args->len);
else
	return -EINVAL;

as I consider args->len && !args->name a bug

That sounds reasonable to me too.