[v2] scsi: qedi: Fix use after free bug in qedi_remove due to race condition

In qedi_probe, it calls __qedi_probe, which bound &qedi->recovery_work
with qedi_recovery_handler and bound &qedi->board_disable_work
with qedi_board_disable_work.

When it calls qedi_schedule_recovery_handler, it will finally
call schedule_delayed_work to start the work.

When we call qedi_remove to remove the driver, there
may be a sequence as follows:

Fix it by finishing the work before cleanup in qedi_remove.

CPU0                  CPU1

                     |qedi_recovery_handler
qedi_remove          |
  __qedi_remove      |
iscsi_host_free      |
scsi_host_put        |
//free shost         |
                     |iscsi_host_for_each_session
                     |//use qedi->shost

Fixes: 4b1068f5d74b ("scsi: qedi: Add MFW error recovery process")
Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
---
v2:
- remove unnecessary comment suggested by Mike Christie and cancel the work
after qedi_ops->stop and qedi_ops->ll2->stop which ensure there is no more
work suggested by Manish Rangankar
---
 drivers/scsi/qedi/qedi_main.c | 3 +++
 1 file changed, 3 insertions(+)

> -----Original Message-----
> From: Zheng Wang <zyytlz.wz@163.com>
> Sent: Thursday, April 13, 2023 9:04 AM
> To: Nilesh Javali <njavali@marvell.com>
> Cc: Manish Rangankar <mrangankar@marvell.com>; GR-QLogic-Storage-
> Upstream <GR-QLogic-Storage-Upstream@marvell.com>;
> jejb@linux.ibm.com; martin.petersen@oracle.com; linux-
> scsi@vger.kernel.org; linux-kernel@vger.kernel.org;
> hackerzheng666@gmail.com; 1395428693sheep@gmail.com;
> alex000young@gmail.com; Zheng Wang <zyytlz.wz@163.com>
> Subject: [EXT] [PATCH v2] scsi: qedi: Fix use after free bug in qedi_remove
> due to race condition
> 
> External Email
> 
> ----------------------------------------------------------------------
> In qedi_probe, it calls __qedi_probe, which bound &qedi->recovery_work
> with qedi_recovery_handler and bound &qedi->board_disable_work with
> qedi_board_disable_work.
> 
> When it calls qedi_schedule_recovery_handler, it will finally call
> schedule_delayed_work to start the work.
> 
> When we call qedi_remove to remove the driver, there may be a sequence
> as follows:
> 
> Fix it by finishing the work before cleanup in qedi_remove.
> 
> CPU0                  CPU1
> 
>                      |qedi_recovery_handler
> qedi_remove          |
>   __qedi_remove      |
> iscsi_host_free      |
> scsi_host_put        |
> //free shost         |
>                      |iscsi_host_for_each_session
>                      |//use qedi->shost
> 
> Fixes: 4b1068f5d74b ("scsi: qedi: Add MFW error recovery process")
> Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
> ---
> v2:
> - remove unnecessary comment suggested by Mike Christie and cancel the
> work after qedi_ops->stop and qedi_ops->ll2->stop which ensure there is no
> more work suggested by Manish Rangankar
> ---
>  drivers/scsi/qedi/qedi_main.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/scsi/qedi/qedi_main.c b/drivers/scsi/qedi/qedi_main.c
> index f2ee49756df8..45d359554182 100644
> --- a/drivers/scsi/qedi/qedi_main.c
> +++ b/drivers/scsi/qedi/qedi_main.c
> @@ -2450,6 +2450,9 @@ static void __qedi_remove(struct pci_dev *pdev,
> int mode)
>  		qedi_ops->ll2->stop(qedi->cdev);
>  	}
> 
> +	cancel_delayed_work_sync(&qedi->recovery_work);
> +	cancel_delayed_work_sync(&qedi->board_disable_work);
> +
>  	qedi_free_iscsi_pf_param(qedi);
> 
>  	rval = qedi_ops->common->update_drv_state(qedi->cdev, false);
> --
> 2.25.1

Thanks,

Acked-by: Manish Rangankar <mrangankar@marvell.com>

Mike Christie <michael.christie@oracle.com> 于2023年4月20日周四 23:39写道：
>
> On 4/12/23 10:34 PM, Zheng Wang wrote:
> > In qedi_probe, it calls __qedi_probe, which bound &qedi->recovery_work
> > with qedi_recovery_handler and bound &qedi->board_disable_work
> > with qedi_board_disable_work.
> >
> > When it calls qedi_schedule_recovery_handler, it will finally
> > call schedule_delayed_work to start the work.
> >
> > When we call qedi_remove to remove the driver, there
> > may be a sequence as follows:
> >
> > Fix it by finishing the work before cleanup in qedi_remove.
> >
> > CPU0                  CPU1
> >
> >                      |qedi_recovery_handler
> > qedi_remove          |
> >   __qedi_remove      |
> > iscsi_host_free      |
> > scsi_host_put        |
> > //free shost         |
> >                      |iscsi_host_for_each_session
> >                      |//use qedi->shost
> >
> > Fixes: 4b1068f5d74b ("scsi: qedi: Add MFW error recovery process")
> > Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
> > ---
> > v2:
> > - remove unnecessary comment suggested by Mike Christie and cancel the work
> > after qedi_ops->stop and qedi_ops->ll2->stop which ensure there is no more
> > work suggested by Manish Rangankar
>
> Look ok to me now. Thanks.
>
> Reviewed-by: Mike Christie <michael.christie@oracle.com>

Thanks for your review.

Best regards,
Zheng