linux-kernel - [PATCH] cgroups: fix possible use after free

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Message-ID: <4991497B.4030200@cn.fujitsu.com>
Date:	Tue, 10 Feb 2009 17:31:39 +0800
From:	Li Zefan <lizf@...fujitsu.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	Paul Menage <menage@...gle.com>, Al Viro <viro@...IV.linux.org.uk>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux Containers <containers@...ts.linux-foundation.org>
Subject: [PATCH] cgroups: fix possible use after free

In cgroup_kill_sb(), root is freed before sb is detached from the list,
so another sget() may find this sb and call cgroup_test_super(),
which will access the root that has been freed.

Reported-by: Al Viro <viro@...IV.linux.org.uk>
Signed-off-by: Li Zefan <lizf@...fujitsu.com>
---
 kernel/cgroup.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 5a54ff4..42fd3f2 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1122,8 +1122,8 @@ static void cgroup_kill_sb(struct super_block *sb) {
 
 	mutex_unlock(&cgroup_mutex);
 
-	kfree(root);
 	kill_litter_super(sb);
+	kfree(root);
 }
 
 static struct file_system_type cgroup_fs_type = {
-- 
1.5.4.rc3
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