| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.19 004/158] cgroup: Fix race condition at rebind_subsystems() | Date | Mon, 29 Aug 2022 12:57:34 +0200 |
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From: Jing-Ting Wu <Jing-Ting.Wu@mediatek.com>
commit 763f4fb76e24959c370cdaa889b2492ba6175580 upstream.
Root cause: The rebind_subsystems() is no lock held when move css object from A list to B list,then let B's head be treated as css node at list_for_each_entry_rcu().
Solution: Add grace period before invalidating the removed rstat_css_node.
Reported-by: Jing-Ting Wu <jing-ting.wu@mediatek.com> Suggested-by: Michal Koutný <mkoutny@suse.com> Signed-off-by: Jing-Ting Wu <jing-ting.wu@mediatek.com> Tested-by: Jing-Ting Wu <jing-ting.wu@mediatek.com> Link: https://lore.kernel.org/linux-arm-kernel/d8f0bc5e2fb6ed259f9334c83279b4c011283c41.camel@mediatek.com/T/ Acked-by: Mukesh Ojha <quic_mojha@quicinc.com> Fixes: a7df69b81aac ("cgroup: rstat: support cgroup1") Cc: stable@vger.kernel.org # v5.13+ Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- kernel/cgroup/cgroup.c | 1 + 1 file changed, 1 insertion(+)
--- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -1811,6 +1811,7 @@ int rebind_subsystems(struct cgroup_root if (ss->css_rstat_flush) { list_del_rcu(&css->rstat_css_node); + synchronize_rcu(); list_add_rcu(&css->rstat_css_node, &dcgrp->rstat_css_list); }
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