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authorLi Zefan <lizefan@huawei.com>2013-01-25 16:08:01 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-03-04 06:03:38 +0800
commitb19c8d0b4c18448006ce960d1c2a3902c481f9b9 (patch)
tree3ac1528bde833d6b4ed9b8412a61415df8b8d547
parent225234a28f6f7655ae3ed5bfbba536d0468209bd (diff)
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.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 7bb63eea6eb8..5bb9bf18438c 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -2511,8 +2511,16 @@ 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",