From: Johannes Weiner <hannes@xxxxxxxxxxx> Subject: 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@xxxxxxxxxxx Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Cc: Nikolay Borisov <kernel@xxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/cgroup.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff -puN kernel/cgroup.c~cgroup-fix-idr-leak-for-the-first-cgroup-root kernel/cgroup.c --- a/kernel/cgroup.c~cgroup-fix-idr-leak-for-the-first-cgroup-root +++ a/kernel/cgroup.c @@ -1160,18 +1160,12 @@ static void cgroup_exit_root_id(struct c { 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); } _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
