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References: <20230413033422.28003-1-zyytlz.wz@163.com> <6a13265d-634e-d52a-44d9-65d05ab28b1a@oracle.com>
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From:   Zheng Hacker <hackerzheng666@gmail.com>
Date:   Fri, 21 Apr 2023 10:45:58 +0800
Message-ID: <CAJedcCzJTq6uFU1fGZ2Qhih4dy6z9DYZOwjrT-P8esMSvL0+cw@mail.gmail.com>
Subject: Re: [PATCH v2] scsi: qedi: Fix use after free bug in qedi_remove due
 to race condition
To:     Mike Christie <michael.christie@oracle.com>
Cc:     Zheng Wang <zyytlz.wz@163.com>, njavali@marvell.com,
        mrangankar@marvell.com, GR-QLogic-Storage-Upstream@marvell.com,
        jejb@linux.ibm.com, martin.petersen@oracle.com,
        linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org,
        1395428693sheep@gmail.com, alex000young@gmail.com
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Mike Christie <michael.christie@oracle.com> =E4=BA=8E2023=E5=B9=B44=E6=9C=
=8820=E6=97=A5=E5=91=A8=E5=9B=9B 23:39=E5=86=99=E9=81=93=EF=BC=9A
>
> 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 m=
ore
> > 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