From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S937863AbcLMRVB (ORCPT ); Tue, 13 Dec 2016 12:21:01 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:57210 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936258AbcLMRQo (ORCPT ); Tue, 13 Dec 2016 12:16:44 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sergey Senozhatsky , Steven Allen , Minchan Kim , Andrew Morton , Linus Torvalds Subject: [PATCH 4.8 08/33] zram: restrict add/remove attributes to root only Date: Tue, 13 Dec 2016 09:16:09 -0800 Message-Id: <20161213171534.519005404@linuxfoundation.org> X-Mailer: git-send-email 2.10.2 In-Reply-To: <20161213171534.171564506@linuxfoundation.org> References: <20161213171534.171564506@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.8-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sergey Senozhatsky commit 5c7e9ccd91b90d87029261f8856294ee51934cab upstream. zram hot_add sysfs attribute is a very 'special' attribute - reading from it creates a new uninitialized zram device. This file, by a mistake, can be read by a 'normal' user at the moment, while only root must be able to create a new zram device, therefore hot_add attribute must have S_IRUSR mode, not S_IRUGO. [akpm@linux-foundation.org: s/sence/sense/, reflow comment to use 80 cols] Fixes: 6566d1a32bf72 ("zram: add dynamic device add/remove functionality") Link: http://lkml.kernel.org/r/20161205155845.20129-1-sergey.senozhatsky@gmail.com Signed-off-by: Sergey Senozhatsky Reported-by: Steven Allen Acked-by: Greg Kroah-Hartman Cc: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- drivers/block/zram/zram_drv.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -1413,8 +1413,14 @@ static ssize_t hot_remove_store(struct c return ret ? ret : count; } +/* + * NOTE: hot_add attribute is not the usual read-only sysfs attribute. In a + * sense that reading from this file does alter the state of your system -- it + * creates a new un-initialized zram device and returns back this device's + * device_id (or an error code if it fails to create a new device). + */ static struct class_attribute zram_control_class_attrs[] = { - __ATTR_RO(hot_add), + __ATTR(hot_add, 0400, hot_add_show, NULL), __ATTR_WO(hot_remove), __ATTR_NULL, };