Messages in this thread | | | Date | Thu, 9 Jun 2022 12:00:31 +0200 | From | Michal Koutný <> | Subject | Re: [PATCH] cgroup: handle cset multiidentity issue when migration |
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Hello.
On Thu, Jun 09, 2022 at 11:49:38AM +0800, 史思远 <shisiyuan19870131@gmail.com> wrote: > The process is like above photo, thread 2 exits > between cgroup_migrate_prepare_dst() and cgroup_migrate_execute(). > Then the refcount of csetX turns to be 0 here, and UAF appears when thread1 > migrating. > Thread2 exits asynchronously, can rwsem prevent it?
See the bailout in cgroup_migrate_add_task():
if (task->flags & PF_EXITING) return;
And cgroup_threadgroup_change_begin(tsk) in exit_signals().
> The purpose of my patch is to keep csetX's refcount still 1 after thread2 > exits, and make sure thread1 migrating successfully.
Why is not src_cset==dst_cset in cgroup_migrate_prepare_dst() not sufficient?
Still, can this be reproduced in real world or is your reasoning based on theory only?
Thanks, Michal
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