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authorJohannes Weiner <hannes@cmpxchg.org>2016-07-26 15:26:58 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-07-26 16:19:19 -0700
commit1fe4d021acbc356723818a633fe0a10c59c2a4c1 (patch)
treeee83530151ecf806ff619a1043fb4c035fc6d7cb /kernel
parent25843c2b21d675c68e512daa4a2b50a18f7a840d (diff)
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 <hannes@cmpxchg.org> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Tejun Heo <tj@kernel.org> Cc: Nikolay Borisov <kernel@kyup.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cgroup.c8
1 files changed, 1 insertions, 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);
}