Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [ 24/30] cpuset: fix cpuset_print_task_mems_allowed() vs rename() race | Date | Fri, 1 Mar 2013 11:45:45 -0800 |
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3.0-stable review patch. If anyone has any objections, please let me know.
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From: Li Zefan <lizefan@huawei.com>
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>
--- kernel/cpuset.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)
--- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -2499,8 +2499,16 @@ void cpuset_print_task_mems_allowed(stru 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",
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