From: Muchun Song Date: Sun, 27 Mar 2022 05:18:52 +0000 (+0800) Subject: mm: kfence: fix missing objcg housekeeping for SLAB X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=dd84d71bcbcb2eb7f889449f6d4a3e65ae439e71;p=linux.git mm: kfence: fix missing objcg housekeeping for SLAB commit ae085d7f9365de7da27ab5c0d16b12d51ea7fca9 upstream. 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 Cc: Dmitry Vyukov Cc: Marco Elver Cc: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- diff --git a/mm/slab.c b/mm/slab.c index 874b3f8fe80da..03d3074d0bb07 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -3429,6 +3429,7 @@ static __always_inline void __cache_free(struct kmem_cache *cachep, void *objp, if (is_kfence_address(objp)) { kmemleak_free_recursive(objp, cachep->flags); + memcg_slab_free_hook(cachep, &objp, 1); __kfence_free(objp); return; }