From: Muchun Song <songmuchun@bytedance.com>
To: hannes@cmpxchg.org, mhocko@kernel.org, vdavydov.dev@gmail.com,
akpm@linux-foundation.org, shakeelb@google.com, guro@fb.com,
iamjoonsoo.kim@lge.com, laoar.shao@gmail.com,
chris@chrisdown.name, christian.brauner@ubuntu.com,
peterz@infradead.org, mingo@kernel.org, keescook@chromium.org,
tglx@linutronix.de, esyr@redhat.com, surenb@google.com,
areber@redhat.com, elver@google.com
Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
linux-mm@kvack.org, Muchun Song <songmuchun@bytedance.com>
Subject: [PATCH 2/5] mm: memcg/slab: Fix use after free in obj_cgroup_charge
Date: Tue, 27 Oct 2020 16:02:53 +0800 [thread overview]
Message-ID: <20201027080256.76497-3-songmuchun@bytedance.com> (raw)
In-Reply-To: <20201027080256.76497-1-songmuchun@bytedance.com>
The rcu_read_lock/unlock only can guarantee that the memcg will
not be freed, but it cannot guarantee the success of css_get to
memcg. This can be happened when we reparent the memcg. So using
css_tryget instead of css_get.
Fixes: bf4f059954dc ("mm: memcg/slab: obj_cgroup API")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
---
mm/memcontrol.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index fcbd79c5023e..c0c27bee23ad 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3223,8 +3223,10 @@ int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size)
* independently later.
*/
rcu_read_lock();
+retry:
memcg = obj_cgroup_memcg(objcg);
- css_get(&memcg->css);
+ if (!css_tryget(&memcg->css))
+ goto retry;
rcu_read_unlock();
nr_pages = size >> PAGE_SHIFT;
--
2.20.1
next prev parent reply other threads:[~2020-10-27 8:07 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-27 8:02 [PATCH 0/5] Fix some bugs in memcg/slab Muchun Song
2020-10-27 8:02 ` [PATCH 1/5] mm: memcg/slab: Fix return child memcg objcg for root memcg Muchun Song
2020-10-27 17:42 ` Roman Gushchin
2020-10-27 19:05 ` Roman Gushchin
2020-10-27 8:02 ` Muchun Song [this message]
2020-10-27 18:31 ` [PATCH 2/5] mm: memcg/slab: Fix use after free in obj_cgroup_charge Roman Gushchin
2020-10-27 8:02 ` [PATCH 3/5] mm: memcg/slab: Rename *_lruvec_slab_state to *_lruvec_kmem_state Muchun Song
2020-10-27 18:37 ` Roman Gushchin
2020-10-27 8:02 ` [PATCH 4/5] mm: memcg/slab: Fix root memcg vmstats Muchun Song
2020-10-27 18:48 ` Roman Gushchin
2020-10-28 2:56 ` [External] " Muchun Song
2020-10-28 3:47 ` Muchun Song
2020-10-29 0:14 ` Roman Gushchin
2020-10-29 6:15 ` Muchun Song
2020-11-10 1:32 ` Roman Gushchin
2020-11-10 2:57 ` Muchun Song
2020-10-27 8:02 ` [PATCH 5/5] mm: memcontrol: Simplify the mem_cgroup_page_lruvec Muchun Song
2020-10-27 13:36 ` Michal Hocko
2020-10-27 14:15 ` [External] " Muchun Song
2020-10-27 14:31 ` Michal Hocko
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