[PATCH 5.10] scsi: core: Fix a use-after-free
From: Maximilian Heyne
Date: Tue Jul 23 2024 - 07:51:10 EST
From: Bart Van Assche <bvanassche@xxxxxxx>
[ Upstream commit 8fe4ce5836e932f5766317cb651c1ff2a4cd0506 ]
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:
<TASK>
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@xxxxxxx
Fixes: 65ca846a5314 ("scsi: core: Introduce {init,exit}_cmd_priv()")
Cc: Ming Lei <ming.lei@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Mike Christie <michael.christie@xxxxxxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxx>
Cc: John Garry <john.garry@xxxxxxxxxx>
Cc: Li Zhijian <lizhijian@xxxxxxxxxxx>
Reported-by: Li Zhijian <lizhijian@xxxxxxxxxxx>
Tested-by: Li Zhijian <lizhijian@xxxxxxxxxxx>
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
[mheyne: fixed contextual conflicts:
- drivers/scsi/hosts.c: due to missing commit 973dac8a8a14 ("scsi: core: Refine how we set tag_set NUMA node")
- drivers/scsi/scsi_sysfs.c: due to missing commit 6f8191fdf41d ("block: simplify disk shutdown")
- drivers/scsi/scsi_scan.c: due to missing commit 59506abe5e34 ("scsi: core: Inline scsi_mq_alloc_queue()")]
Signed-off-by: Maximilian Heyne <mheyne@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v5.10
---
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(-)
diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 297f2b412d07..17fa1cd91da6 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -182,6 +182,15 @@ void scsi_remove_host(struct Scsi_Host *shost)
scsi_proc_host_rm(shost);
scsi_proc_hostdir_rm(shost->hostt);
+ /*
+ * 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));
@@ -240,6 +249,9 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
shost->dma_dev = dma_dev;
+ 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
@@ -312,6 +324,7 @@ 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;
}
@@ -344,9 +357,6 @@ 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_simple_remove(&host_index_ida, shost->host_no);
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 14dec86ff749..64ae7bc2de60 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1923,9 +1923,13 @@ 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 1183dbed687c..3fee9af05925 100644
--- a/drivers/scsi/scsi_priv.h
+++ b/drivers/scsi/scsi_priv.h
@@ -93,7 +93,7 @@ extern void scsi_requeue_run_queue(struct work_struct *work);
extern struct request_queue *scsi_mq_alloc_queue(struct scsi_device *sdev);
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);
struct request_queue;
diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 6f7c4d41c51d..e8703b043805 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -273,6 +273,7 @@ static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget,
kfree(sdev);
goto out;
}
+ kref_get(&sdev->host->tagset_refcnt);
WARN_ON_ONCE(!blk_get_queue(sdev->request_queue));
sdev->request_queue->queuedata = sdev;
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 6cc4d0792e3d..bb37d698da1a 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -1481,6 +1481,7 @@ void __scsi_remove_device(struct scsi_device *sdev)
mutex_unlock(&sdev->state_mutex);
blk_cleanup_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 4a9f1e6e3aac..3979e946c3fd 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -548,6 +548,8 @@ 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;
--
2.40.1
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