Commit 5161b487 authored by Muchun Song's avatar Muchun Song Committed by Andrew Morton
Browse files

mm: list_lru: fix UAF for memory cgroup 

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: 0a97c01c ("list_lru: allow explicit memcg and NUMA node selection")
Signed-off-by: default avatarMuchun Song <songmuchun@bytedance.com>
Acked-by: default avatarShakeel Butt <shakeel.butt@linux.dev>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 7d4df2da

mm/list_lru.c

+22 −6
Original line number Diff line number Diff line
@@ -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);