linux-kernel - [PATCH v2 3/3] mm: memcontrol: add sanity checks for memcg->id.ref on get/put

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <32402ace75b459c8523f5b237a62061e1df7a3b5.1470149524.git.vdavydov@virtuozzo.com>
Date:	Tue, 2 Aug 2016 18:00:50 +0300
From:	Vladimir Davydov <vdavydov@...tuozzo.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	Johannes Weiner <hannes@...xchg.org>,
	Michal Hocko <mhocko@...nel.org>, <linux-mm@...ck.org>,
	<linux-kernel@...r.kernel.org>
Subject: [PATCH v2 3/3] mm: memcontrol: add sanity checks for memcg->id.ref on get/put

Signed-off-by: Vladimir Davydov <vdavydov@...tuozzo.com>
---
 mm/memcontrol.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 67109d556a4a..32b2f33865f9 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4033,6 +4033,7 @@ static DEFINE_IDR(mem_cgroup_idr);
 
 static void mem_cgroup_id_get_many(struct mem_cgroup *memcg, unsigned int n)
 {
+	VM_BUG_ON(atomic_read(&memcg->id.ref) <= 0);
 	atomic_add(n, &memcg->id.ref);
 }
 
@@ -4056,6 +4057,7 @@ static struct mem_cgroup *mem_cgroup_id_get_active(struct mem_cgroup *memcg)
 
 static void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n)
 {
+	VM_BUG_ON(atomic_read(&memcg->id.ref) < n);
 	if (atomic_sub_and_test(n, &memcg->id.ref)) {
 		idr_remove(&mem_cgroup_idr, memcg->id.id);
 		memcg->id.id = 0;
@@ -4176,6 +4178,7 @@ static struct mem_cgroup *mem_cgroup_alloc(void)
 	INIT_LIST_HEAD(&memcg->cgwb_list);
 #endif
 	idr_replace(&mem_cgroup_idr, memcg, memcg->id.id);
+	atomic_set(&memcg->id.ref, 1);
 	return memcg;
 fail:
 	if (memcg->id.id > 0)
@@ -4245,7 +4248,6 @@ fail:
 static int mem_cgroup_css_online(struct cgroup_subsys_state *css)
 {
 	/* Online state pins memcg ID, memcg ID pins CSS */
-	mem_cgroup_id_get(mem_cgroup_from_css(css));
 	css_get(css);
 	return 0;
 }
-- 
2.1.4