diff mbox series

[v2,3/3] scsi: core: Call blk_mq_free_tag_set() earlier

Message ID 20220630213733.17689-4-bvanassche@acm.org (mailing list archive)
State Superseded
Headers show
Series Call blk_mq_free_tag_set() earlier | expand

Commit Message

Bart Van Assche June 30, 2022, 9:37 p.m. UTC
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 moving the .exit_cmd_priv
calls from scsi_host_dev_release() to scsi_forget_host(). Moving
blk_mq_free_tag_set() from scsi_host_dev_release() to scsi_forget_host() is
safe because scsi_forget_host() drains all the request queues that use the
host tag set. This guarantees that no requests are in flight and also that
no new requests will be allocated from the host tag set.

This patch 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

Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: John Garry <john.garry@huawei.com>
Cc: Li Zhijian <lizhijian@fujitsu.com>
Reported-by: Li Zhijian <lizhijian@fujitsu.com>
Tested-by: Li Zhijian <lizhijian@fujitsu.com>
Fixes: 65ca846a5314 ("scsi: core: Introduce {init,exit}_cmd_priv()")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/scsi/hosts.c    | 10 +++++-----
 drivers/scsi/scsi_lib.c |  3 +++
 2 files changed, 8 insertions(+), 5 deletions(-)

Comments

Ming Lei July 1, 2022, 3:44 a.m. UTC | #1
On Thu, Jun 30, 2022 at 02:37:33PM -0700, Bart Van Assche wrote:
> There are two .exit_cmd_priv implementations. Both implementations use
> resources associated with the SCSI host. Make sure that these resources are

Please document what the exact resources associated with this SCSI host is.

We need the root cause.

I understand it might be related with module unloading, since ib_srp may
be gone already, but not sure if it is the exact one in this report.

> still available when .exit_cmd_priv is called by moving the .exit_cmd_priv
> calls from scsi_host_dev_release() to scsi_forget_host(). Moving
> blk_mq_free_tag_set() from scsi_host_dev_release() to scsi_forget_host() is
> safe because scsi_forget_host() drains all the request queues that use the
> host tag set. This guarantees that no requests are in flight and also that
> no new requests will be allocated from the host tag set.
> 
> This patch 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

What is the 8bytes buffer which triggers UAF? what does srp_exit_cmd_priv+0x27
point to?


Thanks, 
Ming
Li Zhijian July 1, 2022, 7:25 a.m. UTC | #2
On 01/07/2022 11:44, Ming Lei wrote:
> On Thu, Jun 30, 2022 at 02:37:33PM -0700, Bart Van Assche wrote:
>> There are two .exit_cmd_priv implementations. Both implementations use
>> resources associated with the SCSI host. Make sure that these resources are
> Please document what the exact resources associated with this SCSI host is.
>
> We need the root cause.
>
> I understand it might be related with module unloading, since ib_srp may
> be gone already, but not sure if it is the exact one in this report.
>
>> still available when .exit_cmd_priv is called by moving the .exit_cmd_priv
>> calls from scsi_host_dev_release() to scsi_forget_host(). Moving
>> blk_mq_free_tag_set() from scsi_host_dev_release() to scsi_forget_host() is
>> safe because scsi_forget_host() drains all the request queues that use the
>> host tag set. This guarantees that no requests are in flight and also that
>> no new requests will be allocated from the host tag set.
>>
>> This patch 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
> What is the 8bytes buffer which triggers UAF? what does srp_exit_cmd_priv+0x27
> point to?
This bug was reported by me, let's input some debug information.
*Attention*: below debug info come from a modified source, so the offset it is a bit different from above one.


[ 120.400572] ib_srp: lizhijian: srp_exit_cmd_priv:975: target_host ffff88810b8d6000, ffff88810b8d67e0 [ 120.400578] ib_srp: lizhijian: srp_exit_cmd_priv:977: target_host ffff88810b8d6000, ffff88810b8d67e0 [ 120.400590] ================================================================== [ 120.400592] BUG: KASAN: use-after-free in srp_exit_cmd_priv+0x6c/0x109 [ib_srp] [ 120.400616] Read of size 8 at addr ffff8881076b1800 by task multipathd/1417 [ 120.400619] [ 120.400621] CPU: 0 PID: 1417 Comm: multipathd Not tainted 5.19.0-rc1-roce-flush+ #85 [ 120.400626] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-27-g64f37cc530f1-prebuilt.qemu.org 04/01/2014
crash> struct srp_target_port.srp_host ffff88810b8d67e0 srp_host = 0xffff8881076b1800, crash> struct srp_target_port.srp_host struct srp_target_port { [104] struct srp_host *srp_host; } crash> struct srp_host.srp_dev 0xffff8881076b1800 srp_dev = 0xffff88800bcd1400, crash> struct srp_device 0xffff88800bcd1400 struct srp_device { dev_list = { next = 0xffff888106fafd00, prev = 0xb680010900000749 }, dev = 0x0, pd = 0x0, global_rkey = 0, mr_page_mask = 3, mr_page_size = 181960704, mr_max_size = -30592, max_pages_per_mr = 117112064, has_fr = 129, use_fast_reg = 136 } crash> dis -s srp_exit_cmd_priv+0x6c
FILE: ../drivers/infiniband/ulp/srp/ib_srp.c
LINE: 978

973 struct srp_request *req;
974
975 pr_info("lizhijian: %s:%d: target_host %px, %px\n", __func__, __LINE__, shost, shost->hostdata);
976 target = host_to_target(shost);
977 pr_info("lizhijian: %s:%d: target_host %px, %px\n", __func__, __LINE__, shost, shost->hostdata);
* 978 dev = target->srp_host->srp_dev;
979 ibdev = dev->dev;
980 req = scsi_cmd_priv(cmd);
981
982 kfree(req->fr_list);
983 if (req->indirect_dma_addr) {
984 ib_dma_unmap_single(ibdev, req->indirect_dma_addr,
985 target->indirect_size,
986 DMA_TO_DEVICE);

Thanks
Zhijian


>
> Thanks,
> Ming
>
Li Zhijian July 1, 2022, 7:45 a.m. UTC | #3
Send again, the format of previous one is wrong.

on 7/1/2022 11:44 AM, Ming Lei wrote:
> On Thu, Jun 30, 2022 at 02:37:33PM -0700, Bart Van Assche wrote:
>> There are two .exit_cmd_priv implementations. Both implementations use
>> resources associated with the SCSI host. Make sure that these resources are
> Please document what the exact resources associated with this SCSI host is.
>
> We need the root cause.
>
> I understand it might be related with module unloading, since ib_srp may
> be gone already, but not sure if it is the exact one in this report.
>
>> still available when .exit_cmd_priv is called by moving the .exit_cmd_priv
>> calls from scsi_host_dev_release() to scsi_forget_host(). Moving
>> blk_mq_free_tag_set() from scsi_host_dev_release() to scsi_forget_host() is
>> safe because scsi_forget_host() drains all the request queues that use the
>> host tag set. This guarantees that no requests are in flight and also that
>> no new requests will be allocated from the host tag set.
>>
>> This patch 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
> What is the 8bytes buffer which triggers UAF? what does srp_exit_cmd_priv+0x27
> point to?

This bug was reported by me, let's input some debug information.
*Attention*: below debug info came from a modified source, so the offset it is a bit different from above one.


[  120.400572] ib_srp: lizhijian: srp_exit_cmd_priv:975: target_host ffff88810b8d6000, ffff88810b8d67e0
[  120.400578] ib_srp: lizhijian: srp_exit_cmd_priv:977: target_host ffff88810b8d6000, ffff88810b8d67e0
[  120.400590] ==================================================================
[  120.400592] BUG: KASAN: use-after-free in srp_exit_cmd_priv+0x6c/0x109 [ib_srp]
[  120.400616] Read of size 8 at addr ffff8881076b1800 by task multipathd/1417
[  120.400619]
[  120.400621] CPU: 0 PID: 1417 Comm: multipathd Not tainted 5.19.0-rc1-roce-flush+ #85
[  120.400626] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-27-g64f37cc530f1-prebuilt.qemu.org 04/01/2014
         


crash> struct srp_target_port.srp_host ffff88810b8d67e0
   srp_host = 0xffff8881076b1800,
crash> struct srp_target_port.srp_host
struct srp_target_port {
   [104] struct srp_host *srp_host;
}

crash> struct srp_host.srp_dev 0xffff8881076b1800
   srp_dev = 0xffff88800bcd1400,


crash> struct srp_device 0xffff88800bcd1400
struct srp_device {
   dev_list = {
     next = 0xffff888106fafd00,
     prev = 0xb680010900000749
   },
   dev = 0x0,
   pd = 0x0,
   global_rkey = 0,
   mr_page_mask = 3,
   mr_page_size = 181960704,
   mr_max_size = -30592,
   max_pages_per_mr = 117112064,
   has_fr = 129,
   use_fast_reg = 136
}


crash> dis -s srp_exit_cmd_priv+0x6c
FILE: ../drivers/infiniband/ulp/srp/ib_srp.c
LINE: 978

   973           struct srp_request *req;
   974
   975           pr_info("lizhijian: %s:%d: target_host %px, %px\n", __func__, __LINE__, shost, shost->hostdata);
   976           target = host_to_target(shost);
   977           pr_info("lizhijian: %s:%d: target_host %px, %px\n", __func__, __LINE__, shost, shost->hostdata);
* 978           dev = target->srp_host->srp_dev;
   979           ibdev = dev->dev;
   980           req = scsi_cmd_priv(cmd);
   981
   982           kfree(req->fr_list);
   983           if (req->indirect_dma_addr) {
   984                   ib_dma_unmap_single(ibdev, req->indirect_dma_addr,
   985                                       target->indirect_size,
   986                                       DMA_TO_DEVICE);
   987           }
   988           kfree(req->indirect_desc);
   989
   990           return 0;
   991   }


Thanks
Zhijian

>
>
> Thanks,
> Ming
>
Bart Van Assche July 1, 2022, 2:07 p.m. UTC | #4
On 6/30/22 20:44, Ming Lei wrote:
> On Thu, Jun 30, 2022 at 02:37:33PM -0700, Bart Van Assche wrote:
>> There are two .exit_cmd_priv implementations. Both implementations use
>> resources associated with the SCSI host. Make sure that these resources are
> 
> Please document what the exact resources associated with this SCSI host is.
> 
> We need the root cause.
> 
> I understand it might be related with module unloading, since ib_srp may
> be gone already, but not sure if it is the exact one in this report.

It is not necessary to unload ib_srp to trigger this scenario. 
Hot-unplugging an RDMA adapter used by the ib_srp driver is sufficient. 
Hot-unplugging triggers a call of srp_remove_one(). srp_remove_one() 
itself and also its caller free resources used by srp_exit_cmd_priv(), 
e.g. struct ib_device.

>> still available when .exit_cmd_priv is called by moving the .exit_cmd_priv
>> calls from scsi_host_dev_release() to scsi_forget_host(). Moving
>> blk_mq_free_tag_set() from scsi_host_dev_release() to scsi_forget_host() is
>> safe because scsi_forget_host() drains all the request queues that use the
>> host tag set. This guarantees that no requests are in flight and also that
>> no new requests will be allocated from the host tag set.
>>
>> This patch 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
> 
> What is the 8bytes buffer which triggers UAF? what does srp_exit_cmd_priv+0x27
> point to?

I think that Li already answered this question.

Thanks,

Bart.
Ming Lei July 1, 2022, 2:37 p.m. UTC | #5
On Fri, Jul 01, 2022 at 07:07:13AM -0700, Bart Van Assche wrote:
> On 6/30/22 20:44, Ming Lei wrote:
> > On Thu, Jun 30, 2022 at 02:37:33PM -0700, Bart Van Assche wrote:
> > > There are two .exit_cmd_priv implementations. Both implementations use
> > > resources associated with the SCSI host. Make sure that these resources are
> > 
> > Please document what the exact resources associated with this SCSI host is.
> > 
> > We need the root cause.
> > 
> > I understand it might be related with module unloading, since ib_srp may
> > be gone already, but not sure if it is the exact one in this report.
> 
> It is not necessary to unload ib_srp to trigger this scenario.
> Hot-unplugging an RDMA adapter used by the ib_srp driver is sufficient.
> Hot-unplugging triggers a call of srp_remove_one(). srp_remove_one() itself
> and also its caller free resources used by srp_exit_cmd_priv(), e.g. struct
> ib_device.

OK, looks it isn't same with Changhui's report.

> 
> > > still available when .exit_cmd_priv is called by moving the .exit_cmd_priv
> > > calls from scsi_host_dev_release() to scsi_forget_host(). Moving
> > > blk_mq_free_tag_set() from scsi_host_dev_release() to scsi_forget_host() is
> > > safe because scsi_forget_host() drains all the request queues that use the
> > > host tag set. This guarantees that no requests are in flight and also that
> > > no new requests will be allocated from the host tag set.
> > > 
> > > This patch 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
> > 
> > What is the 8bytes buffer which triggers UAF? what does srp_exit_cmd_priv+0x27
> > point to?
> 
> I think that Li already answered this question.

OK, from Li's input, the UAF is on the following code:

	struct srp_device *dev = target->srp_host->srp_dev;

So looks you meant target->srp_host is freed by srp_remove_one() before calling
srp_exit_cmd_priv?

Then when is srp_remove_one() triggered? And why is it called before
scsi_remove_host()? Sorry for the stupid question since I am not familiar with srp.


Thanks,
Ming
Bart Van Assche July 1, 2022, 11:58 p.m. UTC | #6
On 7/1/22 07:37, Ming Lei wrote:
> On Fri, Jul 01, 2022 at 07:07:13AM -0700, Bart Van Assche wrote:
>> On 6/30/22 20:44, Ming Lei wrote:
>>> On Thu, Jun 30, 2022 at 02:37:33PM -0700, Bart Van Assche wrote:
>>>> 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
>>>
>>> What is the 8bytes buffer which triggers UAF? what does srp_exit_cmd_priv+0x27
>>> point to?
>>
>> I think that Li already answered this question.
> 
> OK, from Li's input, the UAF is on the following code:
> 
> 	struct srp_device *dev = target->srp_host->srp_dev;
> 
> So looks you meant target->srp_host is freed by srp_remove_one() before calling
> srp_exit_cmd_priv?
> 
> Then when is srp_remove_one() triggered? And why is it called before
> scsi_remove_host()? Sorry for the stupid question since I am not familiar with srp.

Hi Ming,

I think that can happen as the result of the following sequence (will 
look into converting this into a blktests test):
* The Soft-RoCE (or soft-iWARP) driver is bound to a network interface.
   This results in the instantation of an RDMA interface that supports
   RDMA loopback.
* ib_srp and ib_srpt are told to connect to each other over that RDMA
   loopback interface. This results in the creation of a SCSI host and
   one or more SCSI devices.
* The Soft-RoCE (or soft-iWARP) driver is dissociated from all network
   interfaces. This causes the RDMA core to report a hot-unplug event.
   That results in a call of srp_remove_one(). I think the call chain is
   as follows:

rxe_notify()
   ib_unregister_device_queued()
     ib_unregister_work()
         __ib_unregister_device()
           disable_device()
             remove_client_context()
               srp_remove_one()

Bart.
diff mbox series

Patch

diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index ef6c0e37acce..74bfa187fe19 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -182,6 +182,8 @@  void scsi_remove_host(struct Scsi_Host *shost)
 	mutex_unlock(&shost->scan_mutex);
 	scsi_proc_host_rm(shost);
 
+	scsi_mq_destroy_tags(shost);
+
 	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));
@@ -295,8 +297,8 @@  int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
 	return error;
 
 	/*
-	 * Any host allocation in this function will be freed in
-	 * scsi_host_dev_release().
+	 * Any resources associated with the SCSI host in this function except
+	 * the tag set will be freed by scsi_host_dev_release().
 	 */
  out_del_dev:
 	device_del(&shost->shost_dev);
@@ -312,6 +314,7 @@  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);
+	scsi_mq_destroy_tags(shost);
  fail:
 	return error;
 }
@@ -345,9 +348,6 @@  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 6ffc9e4258a8..1aa1a279f8f3 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1990,7 +1990,10 @@  int scsi_mq_setup_tags(struct Scsi_Host *shost)
 
 void scsi_mq_destroy_tags(struct Scsi_Host *shost)
 {
+	if (!shost->tag_set.tags)
+		return;
 	blk_mq_free_tag_set(&shost->tag_set);
+	WARN_ON_ONCE(shost->tag_set.tags);
 }
 
 /**