The patch titled
Subject: mm: list_lru: fix UAF for memory cgroup
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-list_lru-fix-uaf-for-memory-cgroup.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-list_lru-fix-uaf-for-memory-cgroup.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Subject: mm: list_lru: fix UAF for memory cgroup
Date: Thu, 18 Jul 2024 16:36:07 +0800
The mem_cgroup_from_slab_obj() is supposed to be called under rcu lock or
cgroup_mutex or others which could prevent returned memcg from being
freed. Fix it by adding missing rcu read lock.
Found by code inspection.
Link: https://lkml.kernel.org/r/20240718083607.42068-1-songmuchun@xxxxxxxxxxxxx
Fixes: 0a97c01cd20bb ("list_lru: allow explicit memcg and NUMA node selection)
Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Acked-by: Shakeel Butt <shakeel.butt@xxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Nhat Pham <nphamcs@xxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/list_lru.c | 24 ++++++++++++++++++------
1 file changed, 18 insertions(+), 6 deletions(-)
--- a/mm/list_lru.c~mm-list_lru-fix-uaf-for-memory-cgroup
+++ a/mm/list_lru.c
@@ -85,6 +85,7 @@ list_lru_from_memcg_idx(struct list_lru
}
#endif /* CONFIG_MEMCG */
+/* The caller must ensure the memcg lifetime. */
bool list_lru_add(struct list_lru *lru, struct list_head *item, int nid,
struct mem_cgroup *memcg)
{
@@ -109,14 +110,20 @@ EXPORT_SYMBOL_GPL(list_lru_add);
bool list_lru_add_obj(struct list_lru *lru, struct list_head *item)
{
+ bool ret;
int nid = page_to_nid(virt_to_page(item));
- struct mem_cgroup *memcg = list_lru_memcg_aware(lru) ?
- mem_cgroup_from_slab_obj(item) : NULL;
+ struct mem_cgroup *memcg;
- return list_lru_add(lru, item, nid, memcg);
+ rcu_read_lock();
+ memcg = list_lru_memcg_aware(lru) ? mem_cgroup_from_slab_obj(item) : NULL;
+ ret = list_lru_add(lru, item, nid, memcg);
+ rcu_read_unlock();
+
+ return ret;
}
EXPORT_SYMBOL_GPL(list_lru_add_obj);
+/* The caller must ensure the memcg lifetime. */
bool list_lru_del(struct list_lru *lru, struct list_head *item, int nid,
struct mem_cgroup *memcg)
{
@@ -139,11 +146,16 @@ EXPORT_SYMBOL_GPL(list_lru_del);
bool list_lru_del_obj(struct list_lru *lru, struct list_head *item)
{
+ bool ret;
int nid = page_to_nid(virt_to_page(item));
- struct mem_cgroup *memcg = list_lru_memcg_aware(lru) ?
- mem_cgroup_from_slab_obj(item) : NULL;
+ struct mem_cgroup *memcg;
+
+ rcu_read_lock();
+ memcg = list_lru_memcg_aware(lru) ? mem_cgroup_from_slab_obj(item) : NULL;
+ ret = list_lru_del(lru, item, nid, memcg);
+ rcu_read_unlock();
- return list_lru_del(lru, item, nid, memcg);
+ return ret;
}
EXPORT_SYMBOL_GPL(list_lru_del_obj);
_
Patches currently in -mm which might be from songmuchun@xxxxxxxxxxxxx are
mm-list_lru-fix-uaf-for-memory-cgroup.patch
mm-kmem-remove-mem_cgroup_from_obj.patch
