mm: kfence: fix missing objcg housekeeping for SLAB
The objcg is not cleared and put for kfence object when it is freed, which could lead to memory leak for struct obj_cgroup and wrong statistics of NR_SLAB_RECLAIMABLE_B or NR_SLAB_UNRECLAIMABLE_B. Since the last freed object's objcg is not cleared, mem_cgroup_from_obj() could return the wrong memcg when this kfence object, which is not charged to any objcgs, is reallocated to other users. A real word issue [1] is caused by this bug. Link: https://lore.kernel.org/all/000000000000cabcb505dae9e577@google.com/ [1] Reported-by: syzbot+f8c45ccc7d5d45fc5965@syzkaller.appspotmail.com Fixes: d3fb45f370d9 ("mm, kfence: insert KFENCE hooks for SLAB") Signed-off-by: Muchun Song <songmuchun@bytedance.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Marco Elver <elver@google.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -3422,6 +3422,7 @@ static __always_inline void __cache_free(struct kmem_cache *cachep, void *objp,
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if (is_kfence_address(objp)) {
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kmemleak_free_recursive(objp, cachep->flags);
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memcg_slab_free_hook(cachep, &objp, 1);
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__kfence_free(objp);
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return;
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}
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