From: Yu Kuai Date: Tue, 23 May 2023 02:10:17 +0000 (+0800) Subject: md: protect md_thread with rcu X-Git-Tag: microblaze-v6.6~117^2~45^2~14 X-Git-Url: http://git.monstr.eu/?a=commitdiff_plain;h=4469315439827290923fce4f3f672599cabeb366;p=linux-2.6-microblaze.git 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 Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20230523021017.3048783-6-yukuai1@huaweicloud.com --- diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c index 23522df41ca5..ad5a3456cd8a 100644 --- a/drivers/md/md-bitmap.c +++ b/drivers/md/md-bitmap.c @@ -1237,13 +1237,19 @@ 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..3d9fd74233df 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, + + /* daemaon 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 9d54de3441ef..a6ede3d1c99e 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 int remove_and_add_spares(struct mddev *mddev, struct md_rdev *this); static void mddev_detach(struct mddev *mddev); static void export_rdev(struct md_rdev *rdev, struct mddev *mddev); -static void md_wakeup_thread_directly(struct md_thread *thread); +static void md_wakeup_thread_directly(struct md_thread __rcu *thread); /* * Default number of read corrections we'll attempt on an rdev @@ -442,8 +438,10 @@ 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); @@ -811,13 +809,8 @@ void mddev_unlock(struct mddev *mddev) md_free_rdev(mddev); - /* 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); @@ -7903,19 +7896,29 @@ 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); @@ -7945,22 +7948,15 @@ 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); @@ -9226,9 +9222,8 @@ 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 7156fc05f834..a50122165fa1 100644 --- a/drivers/md/md.h +++ b/drivers/md/md.h @@ -365,8 +365,8 @@ 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", @@ -758,8 +758,8 @@ 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 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); 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 381c21f7fb06..0ae7e52983fa 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -982,6 +982,7 @@ 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) @@ -997,12 +998,14 @@ 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 io is issued from raid10d(), nr_pending is not released * from original io(see handle_read_error()). All raise barrier is * blocked until this io is done. */ - if (conf->mddev->thread->tsk == current) { + if (thread->tsk == current) { WARN_ON_ONCE(atomic_read(&conf->nr_pending) == 0); return true; } @@ -4107,7 +4110,8 @@ 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; @@ -4152,8 +4156,8 @@ static int raid10_run(struct mddev *mddev) if (!conf) goto out; - mddev->thread = conf->thread; - conf->thread = NULL; + rcu_assign_pointer(mddev->thread, conf->thread); + rcu_assign_pointer(conf->thread, NULL); if (mddev_is_clustered(conf->mddev)) { int fc, fo; @@ -4296,8 +4300,8 @@ 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; } @@ -4698,8 +4702,8 @@ out: 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 852b265c5db4..47ba7d9e81e1 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 01c55f24ab09..7e2bbcfef325 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -7731,7 +7731,8 @@ 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)); @@ -7954,8 +7955,8 @@ 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; @@ -8052,8 +8053,8 @@ 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; } @@ -8631,8 +8632,8 @@ 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;