linux-kernel - Re: [PATCH net v3] net: ravb: Fix possible UAF bug in ravb

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Date:   Mon, 13 Mar 2023 11:00:08 +0800
From:   Zheng Hacker <hackerzheng666@...il.com>
To:     Sergey Shtylyov <s.shtylyov@....ru>
Cc:     Zheng Wang <zyytlz.wz@....com>, davem@...emloft.net,
        linyunsheng@...wei.com, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, 1395428693sheep@...il.com,
        alex000young@...il.com
Subject: Re: [PATCH net v3] net: ravb: Fix possible UAF bug in ravb_remove

Sergey Shtylyov <s.shtylyov@....ru> 于2023年3月13日周一 04:26写道：
>
> 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@....com>
> > Reviewed-by: Sergey Shtylyov <s.shtylyov@....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 Yunsheng 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/ethernet/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 *pdev)
> >       struct ravb_private *priv = netdev_priv(ndev);
> >       const struct ravb_hw_info *info = 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