Hello Sergey,
> From: Sergey Shtylyov, Sent: Thursday, October 19, 2023 9:36 PM
>
> Hello!
>
> On 10/19/23 2:33 PM, Yoshihiro Shimoda wrote:
>
> > Fix races between ravb_tx_timeout_work() and functions of net_device_ops
> > and ethtool_ops by using rtnl_trylock() and rtnl_unlock(). Note that
> > since ravb_close() is under the rtnl lock and calls cancel_work_sync(),
> > ravb_tx_timeout_work() should calls rtnl_trylock(). Otherwise, a deadlock
> > may happen in ravb_tx_timeout_work() like below:
> >
> > CPU0 CPU1
> > ravb_tx_timeout()
> > schedule_work()
> > ...
> > __dev_close_many()
> > // Under rtnl lock
> > ravb_close()
> > cancel_work_sync()
> > // Waiting
> > ravb_tx_timeout_work()
> > rtnl_lock()
> > // This is possible to cause a deadlock
> >
> > Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
> > Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
>
> Reviewed-by: Sergey Shtylyov <s.shtylyov@xxxxxx>
Thank you for your review!
> [...]
> > diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
> > index 0ef0b88b7145..300c1885e1e1 100644
> > --- a/drivers/net/ethernet/renesas/ravb_main.c
> > +++ b/drivers/net/ethernet/renesas/ravb_main.c
> > @@ -1874,6 +1874,9 @@ static void ravb_tx_timeout_work(struct work_struct *work)
> > struct net_device *ndev = priv->ndev;
> > int error;
> >
> > + if (!rtnl_trylock())
> > + return;
>
> I wonder if we should reschedule the work here...
I think so. But, it should reschedule the work if the netif is still running because
Use-after-free issue happens again when cancel_work_sync() is calling. Also, I also think
we should use schedule_delayed_work() instead. So, I'll submit such a patch as v3.
Best regards,
Yoshihiro Shimoda
> [...]
>
> MBR, Sergey
