From 1fe4d021acbc356723818a633fe0a10c59c2a4c1 Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Tue, 26 Jul 2016 15:26:58 -0700 Subject: [PATCH] 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. Link: http://lkml.kernel.org/r/20160617162359.GB19084@cmpxchg.org Signed-off-by: Johannes Weiner Cc: Vladimir Davydov Cc: Tejun Heo Cc: Nikolay Borisov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/cgroup.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 75c0ff00aca6..3108150e47b1 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1160,18 +1160,12 @@ 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; - } + idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id); } 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); }