Patch "cpuset: fix cpuset_print_task_mems_allowed() vs rename() race" has been added to the 3.4-stable tree

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This is a note to let you know that I've just added the patch titled

    cpuset: fix cpuset_print_task_mems_allowed() vs rename() race

to the 3.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     cpuset-fix-cpuset_print_task_mems_allowed-vs-rename-race.patch
and it can be found in the queue-3.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From 63f43f55c9bbc14f76b582644019b8a07dc8219a Mon Sep 17 00:00:00 2001
From: Li Zefan <lizefan@xxxxxxxxxx>
Date: Fri, 25 Jan 2013 16:08:01 +0800
Subject: cpuset: fix cpuset_print_task_mems_allowed() vs rename() race

From: Li Zefan <lizefan@xxxxxxxxxx>

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 <lizefan@xxxxxxxxxx>
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 kernel/cpuset.c |   12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -2479,8 +2479,16 @@ 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",


Patches currently in stable-queue which might be from lizefan@xxxxxxxxxx are

queue-3.4/cpuset-fix-cpuset_print_task_mems_allowed-vs-rename-race.patch
queue-3.4/cgroup-fix-exit-vs-rmdir-race.patch
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