]> Git Repo - linux.git/commit
mm: memcg/slab: fix use after free in obj_cgroup_charge
authorMuchun Song <[email protected]>
Tue, 15 Dec 2020 03:06:35 +0000 (19:06 -0800)
committerLinus Torvalds <[email protected]>
Tue, 15 Dec 2020 20:13:39 +0000 (12:13 -0800)
commiteefbfa7fd678805b38a46293e78543f98f353d3e
tree352cceee89b01e8291d06f1586a5871a786a16bb
parent2f7659a314736b32b66273dbf91c19874a052fde
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/[email protected]
Fixes: bf4f059954dc ("mm: memcg/slab: obj_cgroup API")
Signed-off-by: Muchun Song <[email protected]>
Acked-by: Roman Gushchin <[email protected]>
Reviewed-by: Shakeel Butt <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Vladimir Davydov <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Yafang Shao <[email protected]>
Cc: Chris Down <[email protected]>
Cc: Christian Brauner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
mm/memcontrol.c
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