From d94b2d00f7bfa0c555e7b8724b1faa037d57d150 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Sun, 21 Aug 2022 15:05:01 -0700 Subject: scsi: core: Revert "Make sure that hosts outlive targets" Revert the patch series "Call blk_mq_free_tag_set() earlier" because it introduces a deadlock if the scsi_remove_host() caller holds a reference on a device, target or host. Link: https://lore.kernel.org/r/20220821220502.13685-4-bvanassche@acm.org Fixes: 16728aaba62e ("scsi: core: Make sure that hosts outlive targets") Reported-by: syzbot+bafeb834708b1bb750bc@syzkaller.appspotmail.com Tested-by: Kenneth R. Crudup Signed-off-by: Bart Van Assche Signed-off-by: Martin K. Petersen --- include/scsi/scsi_host.h | 3 --- 1 file changed, 3 deletions(-) (limited to 'include') diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h index aa7b7496c93a..b6e41ee3d566 100644 --- a/include/scsi/scsi_host.h +++ b/include/scsi/scsi_host.h @@ -690,9 +690,6 @@ struct Scsi_Host { /* ldm bits */ struct device shost_gendev, shost_dev; - atomic_t target_count; - wait_queue_head_t targets_wq; - /* * Points to the transport data (if any) which is allocated * separately -- cgit v1.2.3 From f782201ebc2b5f6c7a22e586e8eb81fe1d9e4801 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Sun, 21 Aug 2022 15:05:02 -0700 Subject: scsi: core: Revert "Make sure that targets outlive devices" Revert the patch series "Call blk_mq_free_tag_set() earlier" because it introduces a deadlock if the scsi_remove_host() caller holds a reference on a device, target or host. Link: https://lore.kernel.org/r/20220821220502.13685-5-bvanassche@acm.org Fixes: fe442604199e ("scsi: core: Make sure that targets outlive devices") Reported-by: syzbot+bafeb834708b1bb750bc@syzkaller.appspotmail.com Tested-by: Kenneth R. Crudup Signed-off-by: Bart Van Assche Signed-off-by: Martin K. Petersen --- drivers/scsi/scsi_scan.c | 2 -- drivers/scsi/scsi_sysfs.c | 20 +++----------------- include/scsi/scsi_device.h | 2 -- 3 files changed, 3 insertions(+), 21 deletions(-) (limited to 'include') diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c index 4c1efd6a3b0c..91ac901a6682 100644 --- a/drivers/scsi/scsi_scan.c +++ b/drivers/scsi/scsi_scan.c @@ -521,8 +521,6 @@ static struct scsi_target *scsi_alloc_target(struct device *parent, starget->state = STARGET_CREATED; starget->scsi_level = SCSI_2; starget->max_target_blocked = SCSI_DEFAULT_TARGET_BLOCKED; - init_waitqueue_head(&starget->sdev_wq); - retry: spin_lock_irqsave(shost->host_lock, flags); diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c index 282b32781e8c..aa70d9282161 100644 --- a/drivers/scsi/scsi_sysfs.c +++ b/drivers/scsi/scsi_sysfs.c @@ -443,9 +443,7 @@ static void scsi_device_cls_release(struct device *class_dev) static void scsi_device_dev_release_usercontext(struct work_struct *work) { - struct scsi_device *sdev = container_of(work, struct scsi_device, - ew.work); - struct scsi_target *starget = sdev->sdev_target; + struct scsi_device *sdev; struct device *parent; struct list_head *this, *tmp; struct scsi_vpd *vpd_pg80 = NULL, *vpd_pg83 = NULL; @@ -454,6 +452,8 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work) unsigned long flags; struct module *mod; + sdev = container_of(work, struct scsi_device, ew.work); + mod = sdev->host->hostt->module; scsi_dh_release_device(sdev); @@ -516,9 +516,6 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work) kfree(sdev->inquiry); kfree(sdev); - if (starget && atomic_dec_return(&starget->sdev_count) == 0) - wake_up(&starget->sdev_wq); - if (parent) put_device(parent); module_put(mod); @@ -1538,14 +1535,6 @@ static void __scsi_remove_target(struct scsi_target *starget) goto restart; } spin_unlock_irqrestore(shost->host_lock, flags); - - /* - * After scsi_remove_target() returns its caller can remove resources - * associated with @starget, e.g. an rport or session. Wait until all - * devices associated with @starget have been removed to prevent that - * a SCSI error handling callback function triggers a use-after-free. - */ - wait_event(starget->sdev_wq, atomic_read(&starget->sdev_count) == 0); } /** @@ -1656,9 +1645,6 @@ void scsi_sysfs_device_initialize(struct scsi_device *sdev) list_add_tail(&sdev->same_target_siblings, &starget->devices); list_add_tail(&sdev->siblings, &shost->__devices); spin_unlock_irqrestore(shost->host_lock, flags); - - atomic_inc(&starget->sdev_count); - /* * device can now only be removed via __scsi_remove_device() so hold * the target. Target will be held in CREATED state until something diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h index 3113471ca375..2493bd65351a 100644 --- a/include/scsi/scsi_device.h +++ b/include/scsi/scsi_device.h @@ -309,8 +309,6 @@ struct scsi_target { struct list_head devices; struct device dev; struct kref reap_ref; /* last put renders target invisible */ - atomic_t sdev_count; - wait_queue_head_t sdev_wq; unsigned int channel; unsigned int id; /* target id ... replace * scsi_device.id eventually */ -- cgit v1.2.3 From 8fe4ce5836e932f5766317cb651c1ff2a4cd0506 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Thu, 25 Aug 2022 17:26:34 -0700 Subject: scsi: core: Fix a use-after-free There are two .exit_cmd_priv implementations. Both implementations use resources associated with the SCSI host. Make sure that these resources are still available when .exit_cmd_priv is called by waiting inside scsi_remove_host() until the tag set has been freed. This commit fixes the following use-after-free: ================================================================== BUG: KASAN: use-after-free in srp_exit_cmd_priv+0x27/0xd0 [ib_srp] Read of size 8 at addr ffff888100337000 by task multipathd/16727 Call Trace: dump_stack_lvl+0x34/0x44 print_report.cold+0x5e/0x5db kasan_report+0xab/0x120 srp_exit_cmd_priv+0x27/0xd0 [ib_srp] scsi_mq_exit_request+0x4d/0x70 blk_mq_free_rqs+0x143/0x410 __blk_mq_free_map_and_rqs+0x6e/0x100 blk_mq_free_tag_set+0x2b/0x160 scsi_host_dev_release+0xf3/0x1a0 device_release+0x54/0xe0 kobject_put+0xa5/0x120 device_release+0x54/0xe0 kobject_put+0xa5/0x120 scsi_device_dev_release_usercontext+0x4c1/0x4e0 execute_in_process_context+0x23/0x90 device_release+0x54/0xe0 kobject_put+0xa5/0x120 scsi_disk_release+0x3f/0x50 device_release+0x54/0xe0 kobject_put+0xa5/0x120 disk_release+0x17f/0x1b0 device_release+0x54/0xe0 kobject_put+0xa5/0x120 dm_put_table_device+0xa3/0x160 [dm_mod] dm_put_device+0xd0/0x140 [dm_mod] free_priority_group+0xd8/0x110 [dm_multipath] free_multipath+0x94/0xe0 [dm_multipath] dm_table_destroy+0xa2/0x1e0 [dm_mod] __dm_destroy+0x196/0x350 [dm_mod] dev_remove+0x10c/0x160 [dm_mod] ctl_ioctl+0x2c2/0x590 [dm_mod] dm_ctl_ioctl+0x5/0x10 [dm_mod] __x64_sys_ioctl+0xb4/0xf0 dm_ctl_ioctl+0x5/0x10 [dm_mod] __x64_sys_ioctl+0xb4/0xf0 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x46/0xb0 Link: https://lore.kernel.org/r/20220826002635.919423-1-bvanassche@acm.org Fixes: 65ca846a5314 ("scsi: core: Introduce {init,exit}_cmd_priv()") Cc: Ming Lei Cc: Christoph Hellwig Cc: Mike Christie Cc: Hannes Reinecke Cc: John Garry Cc: Li Zhijian Reported-by: Li Zhijian Tested-by: Li Zhijian Signed-off-by: Bart Van Assche Signed-off-by: Martin K. Petersen --- drivers/scsi/hosts.c | 16 +++++++++++++--- drivers/scsi/scsi_lib.c | 6 +++++- drivers/scsi/scsi_priv.h | 2 +- drivers/scsi/scsi_scan.c | 1 + drivers/scsi/scsi_sysfs.c | 1 + include/scsi/scsi_host.h | 2 ++ 6 files changed, 23 insertions(+), 5 deletions(-) (limited to 'include') diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c index 26bf3b153595..9857dba09c95 100644 --- a/drivers/scsi/hosts.c +++ b/drivers/scsi/hosts.c @@ -182,6 +182,15 @@ void scsi_remove_host(struct Scsi_Host *shost) mutex_unlock(&shost->scan_mutex); scsi_proc_host_rm(shost); + /* + * New SCSI devices cannot be attached anymore because of the SCSI host + * state so drop the tag set refcnt. Wait until the tag set refcnt drops + * to zero because .exit_cmd_priv implementations may need the host + * pointer. + */ + kref_put(&shost->tagset_refcnt, scsi_mq_free_tags); + wait_for_completion(&shost->tagset_freed); + spin_lock_irqsave(shost->host_lock, flags); if (scsi_host_set_state(shost, SHOST_DEL)) BUG_ON(scsi_host_set_state(shost, SHOST_DEL_RECOVERY)); @@ -245,6 +254,9 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev, if (error) goto fail; + kref_init(&shost->tagset_refcnt); + init_completion(&shost->tagset_freed); + /* * Increase usage count temporarily here so that calling * scsi_autopm_put_host() will trigger runtime idle if there is @@ -317,6 +329,7 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev, pm_runtime_disable(&shost->shost_gendev); pm_runtime_set_suspended(&shost->shost_gendev); pm_runtime_put_noidle(&shost->shost_gendev); + kref_put(&shost->tagset_refcnt, scsi_mq_free_tags); fail: return error; } @@ -350,9 +363,6 @@ static void scsi_host_dev_release(struct device *dev) kfree(dev_name(&shost->shost_dev)); } - if (shost->tag_set.tags) - scsi_mq_destroy_tags(shost); - kfree(shost->shost_data); ida_free(&host_index_ida, shost->host_no); diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index ef08029a0079..96e7e3eaca29 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1983,9 +1983,13 @@ int scsi_mq_setup_tags(struct Scsi_Host *shost) return blk_mq_alloc_tag_set(tag_set); } -void scsi_mq_destroy_tags(struct Scsi_Host *shost) +void scsi_mq_free_tags(struct kref *kref) { + struct Scsi_Host *shost = container_of(kref, typeof(*shost), + tagset_refcnt); + blk_mq_free_tag_set(&shost->tag_set); + complete(&shost->tagset_freed); } /** diff --git a/drivers/scsi/scsi_priv.h b/drivers/scsi/scsi_priv.h index 429663bd78ec..f385b3f04d6e 100644 --- a/drivers/scsi/scsi_priv.h +++ b/drivers/scsi/scsi_priv.h @@ -94,7 +94,7 @@ extern void scsi_run_host_queues(struct Scsi_Host *shost); extern void scsi_requeue_run_queue(struct work_struct *work); extern void scsi_start_queue(struct scsi_device *sdev); extern int scsi_mq_setup_tags(struct Scsi_Host *shost); -extern void scsi_mq_destroy_tags(struct Scsi_Host *shost); +extern void scsi_mq_free_tags(struct kref *kref); extern void scsi_exit_queue(void); extern void scsi_evt_thread(struct work_struct *work); diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c index 91ac901a6682..5d27f5196de6 100644 --- a/drivers/scsi/scsi_scan.c +++ b/drivers/scsi/scsi_scan.c @@ -340,6 +340,7 @@ static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget, kfree(sdev); goto out; } + kref_get(&sdev->host->tagset_refcnt); sdev->request_queue = q; q->queuedata = sdev; __scsi_init_queue(sdev->host, q); diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c index aa70d9282161..5d61f58399dc 100644 --- a/drivers/scsi/scsi_sysfs.c +++ b/drivers/scsi/scsi_sysfs.c @@ -1476,6 +1476,7 @@ void __scsi_remove_device(struct scsi_device *sdev) mutex_unlock(&sdev->state_mutex); blk_mq_destroy_queue(sdev->request_queue); + kref_put(&sdev->host->tagset_refcnt, scsi_mq_free_tags); cancel_work_sync(&sdev->requeue_work); if (sdev->host->hostt->slave_destroy) diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h index b6e41ee3d566..9b0a028bf053 100644 --- a/include/scsi/scsi_host.h +++ b/include/scsi/scsi_host.h @@ -557,6 +557,8 @@ struct Scsi_Host { struct scsi_host_template *hostt; struct scsi_transport_template *transportt; + struct kref tagset_refcnt; + struct completion tagset_freed; /* Area to keep a shared tag map */ struct blk_mq_tag_set tag_set; -- cgit v1.2.3