From mboxrd@z Thu Jan 1 00:00:00 1970 From: Li Zefan Subject: [PATCH] cpuset: fix cpuset_print_task_mems_allowed() vs rename() race Date: Fri, 25 Jan 2013 15:09:48 +0800 Message-ID: <51022FBC.2020705@huawei.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Tejun Heo Cc: LKML , Cgroups , David Rientjes , Al Viro 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. Signed-off-by: Li Zefan --- kernel/cpuset.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 16be7c9..b2476c2 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -2606,8 +2606,12 @@ void cpuset_print_task_mems_allowed(struct task_struct *tsk) dentry = task_cs(tsk)->css.cgroup->dentry; spin_lock(&cpuset_buffer_lock); + + spin_lock(&dentry->d_lock); snprintf(cpuset_name, CPUSET_NAME_LEN, dentry ? (const char *)dentry->d_name.name : "/"); + 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", -- 1.8.0.2