diff options
| author | Yu Kuai <yukuai3@huawei.com> | 2023-05-23 10:10:17 +0800 |
|---|---|---|
| committer | Song Liu <song@kernel.org> | 2023-06-13 15:25:39 -0700 |
| commit | 4469315439827290923fce4f3f672599cabeb366 (patch) | |
| tree | 83e7d30c4570cd28774226f0e9d36b110c823ff8 /drivers/md/raid1.c | |
| parent | 4eeb6535cd51100460ec8873bb68addef17b3e81 (diff) | |
| download | lwn-4469315439827290923fce4f3f672599cabeb366.tar.gz lwn-4469315439827290923fce4f3f672599cabeb366.zip | |
md: protect md_thread with rcu
Currently, there are many places that md_thread can be accessed without
protection, following are known scenarios that can cause
null-ptr-dereference or uaf:
1) sync_thread that is allocated and started from md_start_sync()
2) mddev->thread can be accessed directly from timeout_store() and
md_bitmap_daemon_work()
3) md_unregister_thread() from action_store().
Currently, a global spinlock 'pers_lock' is borrowed to protect
'mddev->thread' in some places, this problem can be fixed likewise,
however, use a global lock for all the cases is not good.
Fix this problem by protecting all md_thread with rcu.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230523021017.3048783-6-yukuai1@huaweicloud.com
Diffstat (limited to 'drivers/md/raid1.c')
| -rw-r--r-- | drivers/md/raid1.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index 3570da63969b..220f6ce761a5 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -3087,7 +3087,8 @@ static struct r1conf *setup_conf(struct mddev *mddev) } err = -ENOMEM; - conf->thread = md_register_thread(raid1d, mddev, "raid1"); + rcu_assign_pointer(conf->thread, + md_register_thread(raid1d, mddev, "raid1")); if (!conf->thread) goto abort; @@ -3180,8 +3181,8 @@ static int raid1_run(struct mddev *mddev) /* * Ok, everything is just fine now */ - mddev->thread = conf->thread; - conf->thread = NULL; + rcu_assign_pointer(mddev->thread, conf->thread); + rcu_assign_pointer(conf->thread, NULL); mddev->private = conf; set_bit(MD_FAILFAST_SUPPORTED, &mddev->flags); |