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mm: list_lru: fix UAF for memory cgroup

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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.

[songmuchun@bytedance.com: only grab rcu lock when necessary, per Vlastimil]
  Link: https://lkml.kernel.org/r/20240801024603.1865-1-songmuchun@bytedance.com
Link: https://lkml.kernel.org/r/20240718083607.42068-1-songmuchun@bytedance.com
Fixes: 0a97c01cd2 ("list_lru: allow explicit memcg and NUMA node selection")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Muchun Song 2024-07-18 16:36:07 +08:00 committed by Andrew Morton
parent 7d4df2dad3
commit 5161b48712
1 changed files with 22 additions and 6 deletions
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28
mm/list_lru.c
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@ -85,6 +85,7 @@ list_lru_from_memcg_idx(struct list_lru *lru, int nid, int idx)
}
#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 +110,22 @@ 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;
return list_lru_add(lru, item, nid, memcg);
if (list_lru_memcg_aware(lru)) {
rcu_read_lock();
ret = list_lru_add(lru, item, nid, mem_cgroup_from_slab_obj(item));
rcu_read_unlock();
} else {
ret = list_lru_add(lru, item, nid, NULL);
}
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 +148,18 @@ 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;
return list_lru_del(lru, item, nid, memcg);
if (list_lru_memcg_aware(lru)) {
rcu_read_lock();
ret = list_lru_del(lru, item, nid, mem_cgroup_from_slab_obj(item));
rcu_read_unlock();
} else {
ret = list_lru_del(lru, item, nid, NULL);
}
return ret;
}
EXPORT_SYMBOL_GPL(list_lru_del_obj);