Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758039Ab3CDD6U (ORCPT ); Sun, 3 Mar 2013 22:58:20 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:32989 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756387Ab3CDDoI (ORCPT ); Sun, 3 Mar 2013 22:44:08 -0500 Message-Id: <20130304033714.231956944@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Mon, 04 Mar 2013 03:38:15 +0000 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: akpm@linux-foundation.org, Li Zefan , Tejun Heo Subject: [ 068/153] cpuset: fix cpuset_print_task_mems_allowed() vs rename() race In-Reply-To: <20130304033707.648729212@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:a11:96ff:fec6:70c4 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1617 Lines: 52 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Li Zefan commit 63f43f55c9bbc14f76b582644019b8a07dc8219a upstream. rename() will change dentry->d_name. The result of this race can be worse than seeing partially rewritten name, but we might access a stale pointer because rename() will re-allocate memory to hold a longer name. It's safe in the protection of dentry->d_lock. v2: check NULL dentry before acquiring dentry lock. Signed-off-by: Li Zefan Signed-off-by: Tejun Heo Signed-off-by: Ben Hutchings --- kernel/cpuset.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -2507,8 +2507,16 @@ void cpuset_print_task_mems_allowed(stru dentry = task_cs(tsk)->css.cgroup->dentry; spin_lock(&cpuset_buffer_lock); - snprintf(cpuset_name, CPUSET_NAME_LEN, - dentry ? (const char *)dentry->d_name.name : "/"); + + if (!dentry) { + strcpy(cpuset_name, "/"); + } else { + spin_lock(&dentry->d_lock); + strlcpy(cpuset_name, (const char *)dentry->d_name.name, + CPUSET_NAME_LEN); + spin_unlock(&dentry->d_lock); + } + nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN, tsk->mems_allowed); printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n", -- 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/