Commit 8c8a5502 authored Jun 17, 2016 by Johannes Weiner Committed by Tejun Heo Jun 17, 2016

cgroup: fix idr leak for the first cgroup root



The valid cgroup hierarchy ID range includes 0, so we can't filter for
positive numbers when freeing it, or it'll leak the first ID. No big
deal, just disruptive when reading the code.

The ID is freed during error handling and when the reference count
hits zero, so the double-free test is not necessary; remove it.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Tejun Heo <tj@kernel.org>

parent db06d759

kernel/cgroup.c

+1 −7

Original line number	Diff line number	Diff line
		@@ -1158,18 +1158,12 @@ static void cgroup_exit_root_id(struct cgroup_root *root)
		{
		lockdep_assert_held(&cgroup_mutex);

		if (root->hierarchy_id) {
		idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id);
		root->hierarchy_id = 0;
		}
		}

		static void cgroup_free_root(struct cgroup_root *root)
		{
		if (root) {
		/* hierarchy ID should already have been released */
		WARN_ON_ONCE(root->hierarchy_id);

		idr_destroy(&root->cgroup_idr);
		kfree(root);
		}

Admin message