mm: kfence: fix missing objcg housekeeping for SLAB
authorMuchun Song <songmuchun@bytedance.com>
Sun, 27 Mar 2022 05:18:52 +0000 (13:18 +0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Mon, 28 Mar 2022 01:47:00 +0000 (18:47 -0700)
commitae085d7f9365de7da27ab5c0d16b12d51ea7fca9
tree30c8132fb43e67b2cb216fe7ff2ff0cdccbf0e80
parentf82da161ea75dc4db21b2499e4b1facd36dab275
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/
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>
mm/slab.c