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Subject[PATCH v2 0/5] md: fix uaf for sync_thread
Date
From: Yu Kuai <yukuai3@huawei.com>

Changes in v2:
- fix a compile error for for md-cluster in patch 2
- replace spin_lock/unlock with spin_lock/unlock_irq in patch 5
- don't wake up inside the new lock in md wakeup_thread in patch 5

Our test reports a uaf for 'mddev->sync_thread':

T1 T2
md_start_sync
md_register_thread
raid1d
md_check_recovery
md_reap_sync_thread
md_unregister_thread
kfree

md_wakeup_thread
wake_up
->sync_thread was freed

Currently, a global spinlock 'pers_lock' is borrowed to protect
'mddev->thread', this problem can be fixed likewise, however, there might
be similar problem for other md_thread, and I really don't like the idea to
borrow a global lock.

This patchset do some refactor, and then use a disk level spinlock to
protect md_thread in relevant apis.

I tested this pathset with mdadm tests, and there are no new regression,
by the way, following test will failed with or without this patchset:

01raid6integ
04r1update
05r6tor0
10ddf-create
10ddf-fail-spare
10ddf-fail-stop-readd
10ddf-geometry

Yu Kuai (5):
md: pass a md_thread pointer to md_register_thread()
md: refactor md_wakeup_thread()
md: use md_thread api to wake up sync_thread
md: pass a mddev to md_unregister_thread()
md: protect md_thread with a new disk level spin lock

drivers/md/dm-raid.c | 6 +-
drivers/md/md-bitmap.c | 6 +-
drivers/md/md-cluster.c | 39 +++++----
drivers/md/md-multipath.c | 8 +-
drivers/md/md.c | 162 ++++++++++++++++++++------------------
drivers/md/md.h | 15 ++--
drivers/md/raid1.c | 19 +++--
drivers/md/raid10.c | 31 ++++----
drivers/md/raid5-cache.c | 19 +++--
drivers/md/raid5-ppl.c | 2 +-
drivers/md/raid5.c | 48 ++++++-----
11 files changed, 177 insertions(+), 178 deletions(-)

--
2.31.1

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