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From:   Zheng Hacker <hackerzheng666@gmail.com>
Date:   Sat, 11 Mar 2023 00:33:01 +0800
Message-ID: <CAJedcCyTn3eM7ptFbW+WPQNC4jaxe=JF5kkWxC3bpnwRA91g-Q@mail.gmail.com>
Subject: Re: [PATCH net] net: ravb: Fix possible UAF bug in ravb_remove
To:     Sergey Shtylyov <s.shtylyov@omp.ru>
Cc:     Zheng Wang <zyytlz.wz@163.com>, davem@davemloft.net,
        edumazet@google.com, kuba@kernel.org, pabeni@redhat.com,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        1395428693sheep@gmail.com, alex000young@gmail.com
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Sergey Shtylyov <s.shtylyov@omp.ru> =E4=BA=8E2023=E5=B9=B43=E6=9C=889=E6=97=
=A5=E5=91=A8=E5=9B=9B 23:47=E5=86=99=E9=81=93=EF=BC=9A
>
> Hello!
>
> On 3/9/23 1:02 PM, Zheng Wang wrote:
>
> > In ravb_probe, priv->work was bound with ravb_tx_timeout_work.
> > If timeout occurs, it will start the work. And if we call
> > ravb_remove without finishing the work, ther may be a use
> > after free bug on ndev.
>
>    Have you actually encountered it?

Sorry, I haven't encountered it. All of the analysis is based on
static analysis.

>
> > Fix it by finishing the job before cleanup in ravb_remove.
> >
> > Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
>
>    Hm... sorry about that. :-)
>
> > Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
>
> Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
>
> [...]
> > diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/eth=
ernet/renesas/ravb_main.c
> > index 0f54849a3823..07a08e72f440 100644
> > --- a/drivers/net/ethernet/renesas/ravb_main.c
> > +++ b/drivers/net/ethernet/renesas/ravb_main.c
> > @@ -2892,6 +2892,7 @@ static int ravb_remove(struct platform_device *pd=
ev)
> >       struct ravb_private *priv =3D netdev_priv(ndev);
> >       const struct ravb_hw_info *info =3D priv->info;
> >
> > +     cancel_work_sync(&priv->work);
>
>    I think we need an empty line here...

Yes, will add it in the next version of patch.

Best regards,
Zheng

>
> >       /* Stop PTP Clock driver */
> >       if (info->ccc_gac)
> >               ravb_ptp_stop(ndev);
>