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From:   Zheng Hacker <hackerzheng666@gmail.com>
Date:   Mon, 13 Mar 2023 11:00:08 +0800
Message-ID: <CAJedcCw2DJWU=C0h_B093AofQw1nnDAQ8AaqVbhb=ea_mMNXWw@mail.gmail.com>
Subject: Re: [PATCH net v3] 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,
        linyunsheng@huawei.com, 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=8813=E6=
=97=A5=E5=91=A8=E4=B8=80 04:26=E5=86=99=E9=81=93=EF=BC=9A
>
> On 3/11/23 9:06 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, there may be a
> > use-after-free bug on ndev.
> >
> > Fix it by finishing the job before cleanup in ravb_remove.
> >
> > Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
> > Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
> > Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
>
>    Well, I haven't reviewed v3 yet...

Please forgive my rudeness, I forgot that..

> > ---
> > v3:
> > - fix typo in commit message
> > v2:
> > - stop dev_watchdog so that handle no more timeout work suggested by Yu=
nsheng Lin,
> > add an empty line to make code clear suggested by Sergey Shtylyov
> > ---
> >  drivers/net/ethernet/renesas/ravb_main.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/eth=
ernet/renesas/ravb_main.c
> > index 0f54849a3823..eb63ea788e19 100644
> > --- a/drivers/net/ethernet/renesas/ravb_main.c
> > +++ b/drivers/net/ethernet/renesas/ravb_main.c
> > @@ -2892,6 +2892,10 @@ static int ravb_remove(struct platform_device *p=
dev)
> >       struct ravb_private *priv =3D netdev_priv(ndev);
> >       const struct ravb_hw_info *info =3D priv->info;
> >
> > +     netif_carrier_off(ndev);
> > +     netif_tx_disable(ndev);
> > +     cancel_work_sync(&priv->work);
> > +
>
>    Thinking about it again (and looking on some drivers): can ravb_remove=
() be
> called without ravb_close() having been called on the bound devices?
>    So I suspect this code should be added to ravb_close()...
>

Yes, as this bug is found by static analysis, I've also seen a lot of
other drivers, many of them put the cancel-work-related code into
*_close as we must close all open file handle before remove a driver.
So I think you'are right. I'll try to add the code to ravb_close.

Best regards,
Zheng