Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753253AbYHYCXn (ORCPT ); Sun, 24 Aug 2008 22:23:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753183AbYHYCXU (ORCPT ); Sun, 24 Aug 2008 22:23:20 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:58812 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752731AbYHYCXS (ORCPT ); Sun, 24 Aug 2008 22:23:18 -0400 Message-ID: <48B2174E.9060608@cn.fujitsu.com> Date: Mon, 25 Aug 2008 10:22:06 +0800 From: Li Zefan User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: Andrew Morton CC: "Serge E. Hallyn" , Paul Menage , LKML , Linux Containers Subject: [PATCH] devcgroup: fix race against rmdir() Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2015 Lines: 74 During the use of a dev_cgroup, we should guarantee the corresponding cgroup won't be deleted (i.e. via rmdir). This can be done through css_get(&dev_cgroup->css), but here we can just get and use the dev_cgroup under rcu_read_lock. And also remove checking NULL dev_cgroup, it won't be NULL since a task always belongs to a cgroup. Signed-off-by: Li Zefan --- security/device_cgroup.c | 18 +++++++++--------- 1 files changed, 9 insertions(+), 9 deletions(-) diff --git a/security/device_cgroup.c b/security/device_cgroup.c index 7bd296c..46f2397 100644 --- a/security/device_cgroup.c +++ b/security/device_cgroup.c @@ -508,12 +508,11 @@ int devcgroup_inode_permission(struct inode *inode, int mask) return 0; if (!S_ISBLK(inode->i_mode) && !S_ISCHR(inode->i_mode)) return 0; - dev_cgroup = css_to_devcgroup(task_subsys_state(current, - devices_subsys_id)); - if (!dev_cgroup) - return 0; rcu_read_lock(); + + dev_cgroup = task_devcgroup(current); + list_for_each_entry_rcu(wh, &dev_cgroup->whitelist, list) { if (wh->type & DEV_ALL) goto acc_check; @@ -533,6 +532,7 @@ acc_check: rcu_read_unlock(); return 0; } + rcu_read_unlock(); return -EPERM; @@ -543,12 +543,10 @@ int devcgroup_inode_mknod(int mode, dev_t dev) struct dev_cgroup *dev_cgroup; struct dev_whitelist_item *wh; - dev_cgroup = css_to_devcgroup(task_subsys_state(current, - devices_subsys_id)); - if (!dev_cgroup) - return 0; - rcu_read_lock(); + + dev_cgroup = task_devcgroup(current); + list_for_each_entry(wh, &dev_cgroup->whitelist, list) { if (wh->type & DEV_ALL) goto acc_check; @@ -566,6 +564,8 @@ acc_check: rcu_read_unlock(); return 0; } + rcu_read_unlock(); + return -EPERM; } -- 1.5.4.rc3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/