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authorLi Zefan2013-01-25 02:08:01 -0600
committerGreg Kroah-Hartman2013-03-03 16:09:06 -0600
commit6403d47ff9392807fcfa4464527193e0cab65b2a (patch)
treee7c5acca575644ed2d09f7eed62476e7f133b75f
parent2212f47b734e5b9461b5c3f555dc653ea7aa212f (diff)
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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 6cbe0330249..ea76c9c5d42 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -2499,8 +2499,16 @@ void cpuset_print_task_mems_allowed(struct task_struct *tsk)
2499 2499
2500 dentry = task_cs(tsk)->css.cgroup->dentry; 2500 dentry = task_cs(tsk)->css.cgroup->dentry;
2501 spin_lock(&cpuset_buffer_lock); 2501 spin_lock(&cpuset_buffer_lock);
2502 snprintf(cpuset_name, CPUSET_NAME_LEN, 2502
2503 dentry ? (const char *)dentry->d_name.name : "/"); 2503 if (!dentry) {
2504 strcpy(cpuset_name, "/");
2505 } else {
2506 spin_lock(&dentry->d_lock);
2507 strlcpy(cpuset_name, (const char *)dentry->d_name.name,
2508 CPUSET_NAME_LEN);
2509 spin_unlock(&dentry->d_lock);
2510 }
2511
2504 nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN, 2512 nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN,
2505 tsk->mems_allowed); 2513 tsk->mems_allowed);
2506 printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n", 2514 printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n",