Messages in this thread | | | Date | Mon, 23 Nov 2015 17:23:44 -0500 | From | Dave Jones <> | Subject | Re: [PATCH cgroup/for-4.4-fixes] cgroup: make css_set pin its css's to avoid use-afer-free |
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On Mon, Nov 23, 2015 at 02:55:41PM -0500, Tejun Heo wrote: > A css_set represents the relationship between a set of tasks and > css's. css_set never pinned the associated css's. This was okay > because tasks used to always disassociate immediately (in RCU sense) - > either a task is moved to a different css_set or exits and never > accesses css_set again. > > Unfortunately, afcf6c8b7544 ("cgroup: add cgroup_subsys->free() method > and use it to fix pids controller") and patches leading up to it made > a zombie hold onto its css_set and deref the associated css's on its > release. Nothing pins the css's after exit and it might have already > been freed leading to use-after-free. > > Fix it by making css_set pin the associate css's until its release.
This gets me booting again, thanks Tejun!
Dave
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