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

[Zheng Hacker]

Manish Rangankar <mrangankar@xxxxxxxxxxx> 于2023年4月20日周四 13:49写道：
>
>
>
> > -----Original Message-----
> > From: Zheng Wang <zyytlz.wz@xxxxxxx>
> > Sent: Thursday, April 13, 2023 9:04 AM
> > To: Nilesh Javali <njavali@xxxxxxxxxxx>
> > Cc: Manish Rangankar <mrangankar@xxxxxxxxxxx>; GR-QLogic-Storage-
> > Upstream <GR-QLogic-Storage-Upstream@xxxxxxxxxxx>;
> > jejb@xxxxxxxxxxxxx; martin.petersen@xxxxxxxxxx; linux-
> > scsi@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> > hackerzheng666@xxxxxxxxx; 1395428693sheep@xxxxxxxxx;
> > alex000young@xxxxxxxxx; Zheng Wang <zyytlz.wz@xxxxxxx>
> > 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@xxxxxxx>
> > ---
> > 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@xxxxxxxxxxx>
>

Thanks for your review.

Best regards,
Zheng