Re: [PATCH v4] net: ravb: Fix possible UAF bug in ravb_remove

[Paolo Abeni <pabeni@redhat.com>]

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/ethernet/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 *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);
> 
> 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. 

> 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