On 2024/6/22 21:45, Markus Elfring wrote:
We found a refcount UAF bug as follows:
BUG: KASAN: use-after-free in cgroup_path_ns+0x112/0x150
…
How do you think about to use a summary phrase like “Avoid use-after-free
in proc_cpuset_show()”?
This is also reported by: https://syzkaller.appspot.com/bug?extid=9b1ff7be974a403aa4cd
Would you like to add any tags (like “Fixes”) accordingly?
Thank you for review, i will do that.
…
+++ b/kernel/cgroup/cpuset.c
…
@@ -5052,9 +5053,28 @@ int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns,
goto out;
css = task_get_css(tsk, cpuset_cgrp_id);
+ rcu_read_lock();
…
+ rcu_read_unlock();
retval = cgroup_path_ns(css->cgroup, buf, PATH_MAX,
current->nsproxy->cgroup_ns);
…
Would you become interested to apply a statement like “guard(rcu_read_lock)();”?
https://elixir.bootlin.com/linux/v6.10-rc4/source/include/linux/cleanup.h#L133
Regards,
Markus
We hope somebody could have another better solution.
Regards
Ridong
