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/[email protected]/ [1] Reported-by: [email protected] Fixes: d3fb45f ("mm, kfence: insert KFENCE hooks for SLAB") Signed-off-by: Muchun Song <[email protected]> Cc: Dmitry Vyukov <[email protected]> Cc: Marco Elver <[email protected]> Cc: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
josf · Mar 28, 2022 · ae085d7 · ae085d7
1 parent f82da16
commit ae085d7
Showing 1 changed file with 1 addition and 0 deletions.
diff --git a/mm/slab.c b/mm/slab.c
@@ -3422,6 +3422,7 @@ 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;
 	}