From: Li Zefan <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
To: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Cgroups <cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
David Rientjes <rientjes-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
Al Viro <viro-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
Subject: [PATCH] cpuset: fix cpuset_print_task_mems_allowed() vs rename() race
Date: Fri, 25 Jan 2013 15:09:48 +0800 [thread overview]
Message-ID: <51022FBC.2020705@huawei.com> (raw)
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 <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
---
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
WARNING: multiple messages have this Message-ID (diff)
From: Li Zefan <lizefan@huawei.com>
To: Tejun Heo <tj@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Cgroups <cgroups@vger.kernel.org>,
David Rientjes <rientjes@google.com>,
Al Viro <viro@ZenIV.linux.org.uk>
Subject: [PATCH] cpuset: fix cpuset_print_task_mems_allowed() vs rename() race
Date: Fri, 25 Jan 2013 15:09:48 +0800 [thread overview]
Message-ID: <51022FBC.2020705@huawei.com> (raw)
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 <lizefan@huawei.com>
---
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
next reply other threads:[~2013-01-25 7:09 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-25 7:09 Li Zefan [this message]
2013-01-25 7:09 ` [PATCH] cpuset: fix cpuset_print_task_mems_allowed() vs rename() race Li Zefan
[not found] ` <51022FBC.2020705-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
2013-01-25 7:26 ` Al Viro
2013-01-25 7:26 ` Al Viro
2013-01-25 7:29 ` Li Zefan
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