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authorMuchun Song <songmuchun@bytedance.com>2020-12-14 19:06:35 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2020-12-15 12:13:39 -0800
commiteefbfa7fd678805b38a46293e78543f98f353d3e (patch)
tree352cceee89b01e8291d06f1586a5871a786a16bb /mm/rmap.c
parent2f7659a314736b32b66273dbf91c19874a052fde (diff)
mm: memcg/slab: fix use after free in obj_cgroup_charge
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. If the whole process of a cgroup offlining is completed between reading a objcg->memcg pointer and bumping the css reference on another CPU, and there are exactly 0 external references to this memory cgroup (how we get to the obj_cgroup_charge() then?), css_get() can change the ref counter from 0 back to 1. Link: https://lkml.kernel.org/r/20201028035013.99711-2-songmuchun@bytedance.com Fixes: bf4f059954dc ("mm: memcg/slab: obj_cgroup API") Signed-off-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Roman Gushchin <guro@fb.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Yafang Shao <laoar.shao@gmail.com> Cc: Chris Down <chris@chrisdown.name> Cc: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/rmap.c')
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