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cpuset: fix cpuset_print_task_mems_allowed() vs rename() race

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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>
Cc: stable@vger.kernel.org
This commit is contained in:
Li Zefan 2013-01-25 16:08:01 +08:00 committed by Tejun Heo
parent 71b5707e11
commit 63f43f55c9
1 changed files with 10 additions and 2 deletions
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12
kernel/cpuset.c
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@ -2511,8 +2511,16 @@ void cpuset_print_task_mems_allowed(struct task_struct *tsk)
dentry = task_cs(tsk)->css.cgroup->dentry; dentry = task_cs(tsk)->css.cgroup->dentry;
spin_lock(&cpuset_buffer_lock); 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, nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN,
tsk->mems_allowed); tsk->mems_allowed);
printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n", printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n",