diff options
| author | Breno Leitao <leitao@debian.org> | 2026-07-16 06:42:18 -0700 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-07-28 17:37:31 -0700 |
| commit | 1833ce36b35426504c64600c94f322437ea44bb2 (patch) | |
| tree | ea028626170c08ce0a5d6907052d8aa8d5735281 | |
| parent | 62cc90241548d5570ee68e01aaba6506964e9811 (diff) | |
mm: memcg: initialize *locked in memcg1_oom_prepare() stub
mem_cgroup_oom() passes an uninitialized "locked" to memcg1_oom_prepare()
and reads it back in memcg1_oom_finish():
bool locked, ret;
...
if (!memcg1_oom_prepare(memcg, &locked))
return false;
ret = mem_cgroup_out_of_memory(memcg, mask, order);
memcg1_oom_finish(memcg, locked);
This relies on memcg1_oom_prepare() setting *locked whenever it returns
true. The CONFIG_MEMCG_V1=y version does, but the stub used when
CONFIG_MEMCG_V1=n returns true without touching *locked, so
memcg1_oom_finish() consumes an uninitialized value. On a memcg OOM this
is reported by UBSAN:
UBSAN: invalid-load in mm/memcontrol.c:1932:27
load of value 0 is not a valid value for type 'bool' (aka '_Bool')
Initialize *locked to false in the stub; with cgroup v1 compiled out there
is no OOM lock to take.
Link: https://lore.kernel.org/20260716-memcg-oom-uninit-locked-v2-1-63631d878eb4@debian.org
Fixes: e93d4166b40a ("mm: memcg: put cgroup v1-specific code under a config option")
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Joshua Hahn <joshua.hahnjy@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: SeongJae Park <sj@kernel.org>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | mm/memcontrol-v1.h | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/mm/memcontrol-v1.h b/mm/memcontrol-v1.h index f92f81108d5e..4fa6e2bc8413 100644 --- a/mm/memcontrol-v1.h +++ b/mm/memcontrol-v1.h @@ -107,7 +107,11 @@ static inline void memcg1_remove_from_trees(struct mem_cgroup *memcg) {} static inline void memcg1_soft_limit_reset(struct mem_cgroup *memcg) {} static inline void memcg1_css_offline(struct mem_cgroup *memcg) {} -static inline bool memcg1_oom_prepare(struct mem_cgroup *memcg, bool *locked) { return true; } +static inline bool memcg1_oom_prepare(struct mem_cgroup *memcg, bool *locked) +{ + *locked = false; + return true; +} static inline void memcg1_oom_finish(struct mem_cgroup *memcg, bool locked) {} static inline void memcg1_oom_recover(struct mem_cgroup *memcg) {} |