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Subject: Re: [PATCH v4] net: ravb: Fix possible UAF bug in ravb_remove
From:   Paolo Abeni <pabeni@redhat.com>
To:     Jakub Kicinski <kuba@kernel.org>, Zheng Wang <zyytlz.wz@163.com>
Cc:     s.shtylyov@omp.ru, lee@kernel.org, linyunsheng@huawei.com,
        davem@davemloft.net, edumazet@google.com, richardcochran@gmail.com,
        p.zabel@pengutronix.de, geert+renesas@glider.be,
        magnus.damm@gmail.com, yoshihiro.shimoda.uh@renesas.com,
        biju.das.jz@bp.renesas.com, wsa+renesas@sang-engineering.com,
        netdev@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
        linux-kernel@vger.kernel.org, hackerzheng666@gmail.com,
        1395428693sheep@gmail.com, alex000young@gmail.com
Date:   Thu, 27 Jul 2023 10:21:07 +0200
In-Reply-To: <20230725201952.2f23bb3b@kernel.org>
References: <20230725030026.1664873-1-zyytlz.wz@163.com>
         <20230725201952.2f23bb3b@kernel.org>
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On Tue, 2023-07-25 at 20:19 -0700, Jakub Kicinski wrote:
> On Tue, 25 Jul 2023 11:00:26 +0800 Zheng Wang wrote:
> > diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/eth=
ernet/renesas/ravb_main.c
> > index 4d6b3b7d6abb..ce2da5101e51 100644
> > --- a/drivers/net/ethernet/renesas/ravb_main.c
> > +++ b/drivers/net/ethernet/renesas/ravb_main.c
> > @@ -2885,6 +2885,9 @@ 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;
> > =20
> > +	netif_carrier_off(ndev);
> > +	netif_tx_disable(ndev);
> > +	cancel_work_sync(&priv->work);
>=20
> Still racy, the carrier can come back up after canceling the work.

I must admit I don't see how/when this driver sets the carrier on ?!?

> But whatever, this is a non-issue in the first place.

Do you mean the UaF can't happen? I think that is real.=20

> The fact that ravb_tx_timeout_work doesn't take any locks seems much
> more suspicious.

Indeed! But that should be a different patch, right?

Waiting a little more for feedback from renesas.

/P