From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752264AbcLEP7A (ORCPT ); Mon, 5 Dec 2016 10:59:00 -0500 Received: from mail-pg0-f65.google.com ([74.125.83.65]:35500 "EHLO mail-pg0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751895AbcLEP66 (ORCPT ); Mon, 5 Dec 2016 10:58:58 -0500 From: Sergey Senozhatsky To: Andrew Morton Cc: Greg KH , Minchan Kim , Steven Allen , linux-kernel@vger.kernel.org, stable@vger.kernel.org, Sergey Senozhatsky , Sergey Senozhatsky Subject: [PATCHv3] zram: restrict add/remove attributes to root only Date: Tue, 6 Dec 2016 00:58:45 +0900 Message-Id: <20161205155845.20129-1-sergey.senozhatsky@gmail.com> X-Mailer: git-send-email 2.10.2 In-Reply-To: <20161204124413.22595-1-sergey.senozhatsky@gmail.com> References: <20161204124413.22595-1-sergey.senozhatsky@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Fixes: 6566d1a32bf72 ("zram: add dynamic device add/remove functionality") Reported-by: Steven Allen Cc: [4.2+] Signed-off-by: Sergey Senozhatsky --- drivers/block/zram/zram_drv.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 5163c8f..cc8d0b5 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -1413,8 +1413,15 @@ static ssize_t hot_remove_store(struct class *class, return ret ? ret : count; } +/* + * NOTE: hot_add attribute is not the usual read-only sysfs + * attribute. In a sence 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, }; -- 2.10.2