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| author | Li Zefan <lizefan@huawei.com> | 2013-01-25 16:08:01 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-03-04 06:06:44 +0800 |
| commit | a74e9a386f6e775f88061f7958b8b34c6742f926 (patch) | |
| tree | a71c10ec1690efe570ec1236198f499faa9c661b | |
| parent | 68412b1718c488e58783d1c576d0aeb34012092d (diff) | |
| download | lwn-a74e9a386f6e775f88061f7958b8b34c6742f926.tar.gz lwn-a74e9a386f6e775f88061f7958b8b34c6742f926.zip | |
cpuset: fix cpuset_print_task_mems_allowed() vs rename() race
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@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | kernel/cpuset.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 5fc1570e64c1..8fe6f6b65006 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -2479,8 +2479,16 @@ void cpuset_print_task_mems_allowed(struct task_struct *tsk) 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", |