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Date: Sun, 23 Apr 2023 10:42:10 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: Yu Kuai <yukuai1@...weicloud.com>, song@...nel.org,
logang@...tatee.com
Cc: linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org,
yi.zhang@...wei.com, yangerkun@...wei.com,
"yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH -next v7 5/5] md: protect md_thread with rcu
Hi,
在 2023/04/14 9:32, Yu Kuai 写道:
> From: Yu Kuai <yukuai3@...wei.com>
>
> Our test reports a uaf for 'mddev->sync_thread':
>
> T1 T2
> md_start_sync
> md_register_thread
> // mddev->sync_thread is set
> raid1d
> md_check_recovery
> md_reap_sync_thread
> md_unregister_thread
> kfree
>
> md_wakeup_thread
> wake_up
> ->sync_thread was freed
>
> Root cause is that there is a small windown between register thread and
> wake up thread, where the thread can be freed concurrently.
>
> Currently, a global spinlock 'pers_lock' is borrowed to protect
> 'mddev->thread', this problem can be fixed likewise, however, there are
> similar problems elsewhere, and use a global lock for all the cases is
> not good.
>
> This patch protect all md_thread with rcu.
Friendly ping... Or do I need to resend the whole patchset for v7?
Thanks,
Kuai
>
> Signed-off-by: Yu Kuai <yukuai3@...wei.com>
> ---
> drivers/md/md-bitmap.c | 10 ++++--
> drivers/md/md-cluster.c | 17 ++++++----
> drivers/md/md-multipath.c | 4 +--
> drivers/md/md.c | 69 ++++++++++++++++++---------------------
> drivers/md/md.h | 8 ++---
> drivers/md/raid1.c | 7 ++--
> drivers/md/raid1.h | 2 +-
> drivers/md/raid10.c | 21 +++++++-----
> drivers/md/raid10.h | 2 +-
> drivers/md/raid5-cache.c | 22 ++++++++-----
> drivers/md/raid5.c | 15 +++++----
> drivers/md/raid5.h | 2 +-
> 12 files changed, 98 insertions(+), 81 deletions(-)
>
> diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
> index 29fd41ef55a6..ab27f66dbb1f 100644
> --- a/drivers/md/md-bitmap.c
> +++ b/drivers/md/md-bitmap.c
> @@ -1221,13 +1221,19 @@ static bitmap_counter_t *md_bitmap_get_counter(struct bitmap_counts *bitmap,
> static void mddev_set_timeout(struct mddev *mddev, unsigned long timeout,
> bool force)
> {
> - struct md_thread *thread = mddev->thread;
> + struct md_thread *thread;
> +
> + rcu_read_lock();
> + thread = rcu_dereference(mddev->thread);
>
> if (!thread)
> - return;
> + goto out;
>
> if (force || thread->timeout < MAX_SCHEDULE_TIMEOUT)
> thread->timeout = timeout;
> +
> +out:
> + rcu_read_unlock();
> }
>
> /*
> diff --git a/drivers/md/md-cluster.c b/drivers/md/md-cluster.c
> index 10e0c5381d01..bd2e0c61b2e6 100644
> --- a/drivers/md/md-cluster.c
> +++ b/drivers/md/md-cluster.c
> @@ -75,14 +75,14 @@ struct md_cluster_info {
> sector_t suspend_hi;
> int suspend_from; /* the slot which broadcast suspend_lo/hi */
>
> - struct md_thread *recovery_thread;
> + struct md_thread __rcu *recovery_thread;
> unsigned long recovery_map;
> /* communication loc resources */
> struct dlm_lock_resource *ack_lockres;
> struct dlm_lock_resource *message_lockres;
> struct dlm_lock_resource *token_lockres;
> struct dlm_lock_resource *no_new_dev_lockres;
> - struct md_thread *recv_thread;
> + struct md_thread __rcu *recv_thread;
> struct completion newdisk_completion;
> wait_queue_head_t wait;
> unsigned long state;
> @@ -362,8 +362,8 @@ static void __recover_slot(struct mddev *mddev, int slot)
>
> set_bit(slot, &cinfo->recovery_map);
> if (!cinfo->recovery_thread) {
> - cinfo->recovery_thread = md_register_thread(recover_bitmaps,
> - mddev, "recover");
> + rcu_assign_pointer(cinfo->recovery_thread,
> + md_register_thread(recover_bitmaps, mddev, "recover"));
> if (!cinfo->recovery_thread) {
> pr_warn("md-cluster: Could not create recovery thread\n");
> return;
> @@ -526,11 +526,15 @@ static void process_add_new_disk(struct mddev *mddev, struct cluster_msg *cmsg)
> static void process_metadata_update(struct mddev *mddev, struct cluster_msg *msg)
> {
> int got_lock = 0;
> + struct md_thread *thread;
> struct md_cluster_info *cinfo = mddev->cluster_info;
> mddev->good_device_nr = le32_to_cpu(msg->raid_slot);
>
> dlm_lock_sync(cinfo->no_new_dev_lockres, DLM_LOCK_CR);
> - wait_event(mddev->thread->wqueue,
> +
> + /* demaon thread must exist */
> + thread = rcu_dereference_protected(mddev->thread, true);
> + wait_event(thread->wqueue,
> (got_lock = mddev_trylock(mddev)) ||
> test_bit(MD_CLUSTER_HOLDING_MUTEX_FOR_RECVD, &cinfo->state));
> md_reload_sb(mddev, mddev->good_device_nr);
> @@ -889,7 +893,8 @@ static int join(struct mddev *mddev, int nodes)
> }
> /* Initiate the communication resources */
> ret = -ENOMEM;
> - cinfo->recv_thread = md_register_thread(recv_daemon, mddev, "cluster_recv");
> + rcu_assign_pointer(cinfo->recv_thread,
> + md_register_thread(recv_daemon, mddev, "cluster_recv"));
> if (!cinfo->recv_thread) {
> pr_err("md-cluster: cannot allocate memory for recv_thread!\n");
> goto err;
> diff --git a/drivers/md/md-multipath.c b/drivers/md/md-multipath.c
> index 66edf5e72bd6..92c45be203d7 100644
> --- a/drivers/md/md-multipath.c
> +++ b/drivers/md/md-multipath.c
> @@ -400,8 +400,8 @@ static int multipath_run (struct mddev *mddev)
> if (ret)
> goto out_free_conf;
>
> - mddev->thread = md_register_thread(multipathd, mddev,
> - "multipath");
> + rcu_assign_pointer(mddev->thread,
> + md_register_thread(multipathd, mddev, "multipath"));
> if (!mddev->thread)
> goto out_free_conf;
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index e3c30500bd15..f680eccf4197 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -70,11 +70,7 @@
> #include "md-bitmap.h"
> #include "md-cluster.h"
>
> -/* pers_list is a list of registered personalities protected
> - * by pers_lock.
> - * pers_lock does extra service to protect accesses to
> - * mddev->thread when the mutex cannot be held.
> - */
> +/* pers_list is a list of registered personalities protected by pers_lock. */
> static LIST_HEAD(pers_list);
> static DEFINE_SPINLOCK(pers_lock);
>
> @@ -92,7 +88,7 @@ static struct workqueue_struct *md_rdev_misc_wq;
> static int remove_and_add_spares(struct mddev *mddev,
> struct md_rdev *this);
> static void mddev_detach(struct mddev *mddev);
> -static void md_wakeup_thread_directly(struct md_thread *thread);
> +static void md_wakeup_thread_directly(struct md_thread __rcu *thread);
>
> enum md_ro_state {
> MD_RDWR,
> @@ -458,8 +454,10 @@ static void md_submit_bio(struct bio *bio)
> */
> void mddev_suspend(struct mddev *mddev)
> {
> - WARN_ON_ONCE(mddev->thread && current == mddev->thread->tsk);
> - lockdep_assert_held(&mddev->reconfig_mutex);
> + struct md_thread *thread = rcu_dereference_protected(mddev->thread,
> + lockdep_is_held(&mddev->reconfig_mutex));
> +
> + WARN_ON_ONCE(thread && current == thread->tsk);
> if (mddev->suspended++)
> return;
> wake_up(&mddev->sb_wait);
> @@ -801,13 +799,8 @@ void mddev_unlock(struct mddev *mddev)
> } else
> mutex_unlock(&mddev->reconfig_mutex);
>
> - /* As we've dropped the mutex we need a spinlock to
> - * make sure the thread doesn't disappear
> - */
> - spin_lock(&pers_lock);
> md_wakeup_thread(mddev->thread);
> wake_up(&mddev->sb_wait);
> - spin_unlock(&pers_lock);
> }
> EXPORT_SYMBOL_GPL(mddev_unlock);
>
> @@ -7891,19 +7884,29 @@ static int md_thread(void *arg)
> return 0;
> }
>
> -static void md_wakeup_thread_directly(struct md_thread *thread)
> +static void md_wakeup_thread_directly(struct md_thread __rcu *thread)
> {
> - if (thread)
> - wake_up_process(thread->tsk);
> + struct md_thread *t;
> +
> + rcu_read_lock();
> + t = rcu_dereference(thread);
> + if (t)
> + wake_up_process(t->tsk);
> + rcu_read_unlock();
> }
>
> -void md_wakeup_thread(struct md_thread *thread)
> +void md_wakeup_thread(struct md_thread __rcu *thread)
> {
> - if (thread) {
> - pr_debug("md: waking up MD thread %s.\n", thread->tsk->comm);
> - set_bit(THREAD_WAKEUP, &thread->flags);
> - wake_up(&thread->wqueue);
> + struct md_thread *t;
> +
> + rcu_read_lock();
> + t = rcu_dereference(thread);
> + if (t) {
> + pr_debug("md: waking up MD thread %s.\n", t->tsk->comm);
> + set_bit(THREAD_WAKEUP, &t->flags);
> + wake_up(&t->wqueue);
> }
> + rcu_read_unlock();
> }
> EXPORT_SYMBOL(md_wakeup_thread);
>
> @@ -7933,22 +7936,15 @@ struct md_thread *md_register_thread(void (*run) (struct md_thread *),
> }
> EXPORT_SYMBOL(md_register_thread);
>
> -void md_unregister_thread(struct md_thread **threadp)
> +void md_unregister_thread(struct md_thread __rcu **threadp)
> {
> - struct md_thread *thread;
> + struct md_thread *thread = rcu_dereference_protected(*threadp, true);
>
> - /*
> - * Locking ensures that mddev_unlock does not wake_up a
> - * non-existent thread
> - */
> - spin_lock(&pers_lock);
> - thread = *threadp;
> - if (!thread) {
> - spin_unlock(&pers_lock);
> + if (!thread)
> return;
> - }
> - *threadp = NULL;
> - spin_unlock(&pers_lock);
> +
> + rcu_assign_pointer(*threadp, NULL);
> + synchronize_rcu();
>
> pr_debug("interrupting MD-thread pid %d\n", task_pid_nr(thread->tsk));
> kthread_stop(thread->tsk);
> @@ -9210,9 +9206,8 @@ static void md_start_sync(struct work_struct *ws)
> {
> struct mddev *mddev = container_of(ws, struct mddev, del_work);
>
> - mddev->sync_thread = md_register_thread(md_do_sync,
> - mddev,
> - "resync");
> + rcu_assign_pointer(mddev->sync_thread,
> + md_register_thread(md_do_sync, mddev, "resync"));
> if (!mddev->sync_thread) {
> pr_warn("%s: could not start resync thread...\n",
> mdname(mddev));
> diff --git a/drivers/md/md.h b/drivers/md/md.h
> index e148e3c83b0d..324558c3fa06 100644
> --- a/drivers/md/md.h
> +++ b/drivers/md/md.h
> @@ -367,8 +367,8 @@ struct mddev {
> int new_chunk_sectors;
> int reshape_backwards;
>
> - struct md_thread *thread; /* management thread */
> - struct md_thread *sync_thread; /* doing resync or reconstruct */
> + struct md_thread __rcu *thread; /* management thread */
> + struct md_thread __rcu *sync_thread; /* doing resync or reconstruct */
>
> /* 'last_sync_action' is initialized to "none". It is set when a
> * sync operation (i.e "data-check", "requested-resync", "resync",
> @@ -734,8 +734,8 @@ extern struct md_thread *md_register_thread(
> void (*run)(struct md_thread *thread),
> struct mddev *mddev,
> const char *name);
> -extern void md_unregister_thread(struct md_thread **threadp);
> -extern void md_wakeup_thread(struct md_thread *thread);
> +extern void md_unregister_thread(struct md_thread __rcu **threadp);
> +extern void md_wakeup_thread(struct md_thread __rcu *thread);
> extern void md_check_recovery(struct mddev *mddev);
> extern void md_reap_sync_thread(struct mddev *mddev);
> extern int mddev_init_writes_pending(struct mddev *mddev);
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index 68a9e2d9985b..2f1011ffdf09 100644
> --- a/drivers/md/raid1.c
> +++ b/drivers/md/raid1.c
> @@ -3084,7 +3084,8 @@ 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;
>
> @@ -3177,8 +3178,8 @@ 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);
>
> diff --git a/drivers/md/raid1.h b/drivers/md/raid1.h
> index ebb6788820e7..468f189da7a0 100644
> --- a/drivers/md/raid1.h
> +++ b/drivers/md/raid1.h
> @@ -130,7 +130,7 @@ struct r1conf {
> /* When taking over an array from a different personality, we store
> * the new thread here until we fully activate the array.
> */
> - struct md_thread *thread;
> + struct md_thread __rcu *thread;
>
> /* Keep track of cluster resync window to send to other
> * nodes.
> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
> index 6c66357f92f5..6590aa49598c 100644
> --- a/drivers/md/raid10.c
> +++ b/drivers/md/raid10.c
> @@ -980,6 +980,7 @@ static void lower_barrier(struct r10conf *conf)
> static bool stop_waiting_barrier(struct r10conf *conf)
> {
> struct bio_list *bio_list = current->bio_list;
> + struct md_thread *thread;
>
> /* barrier is dropped */
> if (!conf->barrier)
> @@ -995,8 +996,11 @@ static bool stop_waiting_barrier(struct r10conf *conf)
> (!bio_list_empty(&bio_list[0]) || !bio_list_empty(&bio_list[1])))
> return true;
>
> + /* daemon thread must exist while handling io */
> + thread = rcu_dereference_protected(conf->mddev->thread, true);
> +
> /* move on if recovery thread is blocked by us */
> - if (conf->mddev->thread->tsk == current &&
> + if (thread->tsk == current &&
> test_bit(MD_RECOVERY_RUNNING, &conf->mddev->recovery) &&
> conf->nr_queued > 0)
> return true;
> @@ -4078,7 +4082,8 @@ static struct r10conf *setup_conf(struct mddev *mddev)
> atomic_set(&conf->nr_pending, 0);
>
> err = -ENOMEM;
> - conf->thread = md_register_thread(raid10d, mddev, "raid10");
> + rcu_assign_pointer(conf->thread,
> + md_register_thread(raid10d, mddev, "raid10"));
> if (!conf->thread)
> goto out;
>
> @@ -4141,8 +4146,8 @@ static int raid10_run(struct mddev *mddev)
> }
> }
>
> - mddev->thread = conf->thread;
> - conf->thread = NULL;
> + rcu_assign_pointer(mddev->thread, conf->thread);
> + rcu_assign_pointer(conf->thread, NULL);
>
> if (mddev->queue) {
> blk_queue_max_write_zeroes_sectors(mddev->queue, 0);
> @@ -4273,8 +4278,8 @@ static int raid10_run(struct mddev *mddev)
> clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
> set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
> set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
> - mddev->sync_thread = md_register_thread(md_do_sync, mddev,
> - "reshape");
> + rcu_assign_pointer(mddev->sync_thread,
> + md_register_thread(md_do_sync, mddev, "reshape"));
> if (!mddev->sync_thread)
> goto out_free_conf;
> }
> @@ -4686,8 +4691,8 @@ static int raid10_start_reshape(struct mddev *mddev)
> set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
> set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
>
> - mddev->sync_thread = md_register_thread(md_do_sync, mddev,
> - "reshape");
> + rcu_assign_pointer(mddev->sync_thread,
> + md_register_thread(md_do_sync, mddev, "reshape"));
> if (!mddev->sync_thread) {
> ret = -EAGAIN;
> goto abort;
> diff --git a/drivers/md/raid10.h b/drivers/md/raid10.h
> index 8c072ce0bc54..63e48b11b552 100644
> --- a/drivers/md/raid10.h
> +++ b/drivers/md/raid10.h
> @@ -100,7 +100,7 @@ struct r10conf {
> /* When taking over an array from a different personality, we store
> * the new thread here until we fully activate the array.
> */
> - struct md_thread *thread;
> + struct md_thread __rcu *thread;
>
> /*
> * Keep track of cluster resync window to send to other nodes.
> diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
> index 46182b955aef..040f5d6e1298 100644
> --- a/drivers/md/raid5-cache.c
> +++ b/drivers/md/raid5-cache.c
> @@ -120,7 +120,7 @@ struct r5l_log {
> struct bio_set bs;
> mempool_t meta_pool;
>
> - struct md_thread *reclaim_thread;
> + struct md_thread __rcu *reclaim_thread;
> unsigned long reclaim_target; /* number of space that need to be
> * reclaimed. if it's 0, reclaim spaces
> * used by io_units which are in
> @@ -1576,17 +1576,18 @@ void r5l_wake_reclaim(struct r5l_log *log, sector_t space)
>
> void r5l_quiesce(struct r5l_log *log, int quiesce)
> {
> - struct mddev *mddev;
> + struct mddev *mddev = log->rdev->mddev;
> + struct md_thread *thread = rcu_dereference_protected(
> + log->reclaim_thread, lockdep_is_held(&mddev->reconfig_mutex));
>
> if (quiesce) {
> /* make sure r5l_write_super_and_discard_space exits */
> - mddev = log->rdev->mddev;
> wake_up(&mddev->sb_wait);
> - kthread_park(log->reclaim_thread->tsk);
> + kthread_park(thread->tsk);
> r5l_wake_reclaim(log, MaxSector);
> r5l_do_reclaim(log);
> } else
> - kthread_unpark(log->reclaim_thread->tsk);
> + kthread_unpark(thread->tsk);
> }
>
> bool r5l_log_disk_error(struct r5conf *conf)
> @@ -3063,6 +3064,7 @@ void r5c_update_on_rdev_error(struct mddev *mddev, struct md_rdev *rdev)
> int r5l_init_log(struct r5conf *conf, struct md_rdev *rdev)
> {
> struct r5l_log *log;
> + struct md_thread *thread;
> int ret;
>
> pr_debug("md/raid:%s: using device %pg as journal\n",
> @@ -3121,11 +3123,13 @@ int r5l_init_log(struct r5conf *conf, struct md_rdev *rdev)
> spin_lock_init(&log->tree_lock);
> INIT_RADIX_TREE(&log->big_stripe_tree, GFP_NOWAIT | __GFP_NOWARN);
>
> - log->reclaim_thread = md_register_thread(r5l_reclaim_thread,
> - log->rdev->mddev, "reclaim");
> - if (!log->reclaim_thread)
> + thread = md_register_thread(r5l_reclaim_thread, log->rdev->mddev,
> + "reclaim");
> + if (!thread)
> goto reclaim_thread;
> - log->reclaim_thread->timeout = R5C_RECLAIM_WAKEUP_INTERVAL;
> +
> + thread->timeout = R5C_RECLAIM_WAKEUP_INTERVAL;
> + rcu_assign_pointer(log->reclaim_thread, thread);
>
> init_waitqueue_head(&log->iounit_wait);
>
> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> index 7b820b81d8c2..1f68bba9d0b9 100644
> --- a/drivers/md/raid5.c
> +++ b/drivers/md/raid5.c
> @@ -7665,7 +7665,8 @@ static struct r5conf *setup_conf(struct mddev *mddev)
> }
>
> sprintf(pers_name, "raid%d", mddev->new_level);
> - conf->thread = md_register_thread(raid5d, mddev, pers_name);
> + rcu_assign_pointer(conf->thread,
> + md_register_thread(raid5d, mddev, pers_name));
> if (!conf->thread) {
> pr_warn("md/raid:%s: couldn't allocate thread.\n",
> mdname(mddev));
> @@ -7889,8 +7890,8 @@ static int raid5_run(struct mddev *mddev)
> }
>
> conf->min_offset_diff = min_offset_diff;
> - mddev->thread = conf->thread;
> - conf->thread = NULL;
> + rcu_assign_pointer(mddev->thread, conf->thread);
> + rcu_assign_pointer(conf->thread, NULL);
> mddev->private = conf;
>
> for (i = 0; i < conf->raid_disks && conf->previous_raid_disks;
> @@ -7989,8 +7990,8 @@ static int raid5_run(struct mddev *mddev)
> clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
> set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
> set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
> - mddev->sync_thread = md_register_thread(md_do_sync, mddev,
> - "reshape");
> + rcu_assign_pointer(mddev->sync_thread,
> + md_register_thread(md_do_sync, mddev, "reshape"));
> if (!mddev->sync_thread)
> goto abort;
> }
> @@ -8567,8 +8568,8 @@ static int raid5_start_reshape(struct mddev *mddev)
> clear_bit(MD_RECOVERY_DONE, &mddev->recovery);
> set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
> set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
> - mddev->sync_thread = md_register_thread(md_do_sync, mddev,
> - "reshape");
> + rcu_assign_pointer(mddev->sync_thread,
> + md_register_thread(md_do_sync, mddev, "reshape"));
> if (!mddev->sync_thread) {
> mddev->recovery = 0;
> spin_lock_irq(&conf->device_lock);
> diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
> index e873938a6125..f19707189a7b 100644
> --- a/drivers/md/raid5.h
> +++ b/drivers/md/raid5.h
> @@ -679,7 +679,7 @@ struct r5conf {
> /* When taking over an array from a different personality, we store
> * the new thread here until we fully activate the array.
> */
> - struct md_thread *thread;
> + struct md_thread __rcu *thread;
> struct list_head temp_inactive_list[NR_STRIPE_HASH_LOCKS];
> struct r5worker_group *worker_groups;
> int group_cnt;
>
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