2023-04-13 07:16:10

by Zheng Wang

Subject: [PATCH net v2] net: ethernet: fix use after free bug in ns83820_remove_one due to race condition

In ns83820_init_one, dev->tq_refill was bound with queue_refill.

If irq happens, it will call ns83820_irq->ns83820_do_isr.
Then it invokes tasklet_schedule(&dev->rx_tasklet) to start
rx_action function. And rx_action will call ns83820_rx_kick
and finally start queue_refill function.

If we remove the driver without finishing the work, there
may be a race condition between ndev, which may cause UAF
bug.

CPU0 CPU1

|queue_refill
ns83820_remove_one |
free_netdev |
put_device |
free ndev |
|rx_refill
|//use ndev

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Zheng Wang <[email protected]>
---
v2:
- cancel the work after unregister_netdev to make sure there
is no more request suggested by Jakub Kicinski
---
drivers/net/ethernet/natsemi/ns83820.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/natsemi/ns83820.c b/drivers/net/ethernet/natsemi/ns83820.c
index 998586872599..2e84b9fcd8e9 100644
--- a/drivers/net/ethernet/natsemi/ns83820.c
+++ b/drivers/net/ethernet/natsemi/ns83820.c
@@ -2208,8 +2208,13 @@ static void ns83820_remove_one(struct pci_dev *pci_dev)

ns83820_disable_interrupts(dev); /* paranoia */

+ netif_carrier_off(ndev);
+ netif_tx_disable(ndev);
+
unregister_netdev(ndev);
free_irq(dev->pci_dev->irq, ndev);
+ cancel_work_sync(&dev->tq_refill);
+
iounmap(dev->base);
dma_free_coherent(&dev->pci_dev->dev, 4 * DESC_SIZE * NR_TX_DESC,
dev->tx_descs, dev->tx_phy_descs);
--
2.25.1

2023-04-13 10:10:29

by Horatiu Vultur

Subject: Re: [PATCH net v2] net: ethernet: fix use after free bug in ns83820_remove_one due to race condition

The 04/13/2023 15:14, Zheng Wang wrote:

Hi Zheng,

>
> In ns83820_init_one, dev->tq_refill was bound with queue_refill.
>
> If irq happens, it will call ns83820_irq->ns83820_do_isr.
> Then it invokes tasklet_schedule(&dev->rx_tasklet) to start
> rx_action function. And rx_action will call ns83820_rx_kick
> and finally start queue_refill function.
>
> If we remove the driver without finishing the work, there
> may be a race condition between ndev, which may cause UAF
> bug.
>
> CPU0 CPU1
>
> |queue_refill
> ns83820_remove_one |
> free_netdev |
> put_device |
> free ndev |
> |rx_refill
> |//use ndev

Will you not have the same issue if you remove the driver after you
schedule rx_tasklet? Because rx_action will use also ndev.

>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Zheng Wang <[email protected]>
> ---
> v2:
> - cancel the work after unregister_netdev to make sure there
> is no more request suggested by Jakub Kicinski
> ---
> drivers/net/ethernet/natsemi/ns83820.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/net/ethernet/natsemi/ns83820.c b/drivers/net/ethernet/natsemi/ns83820.c
> index 998586872599..2e84b9fcd8e9 100644
> --- a/drivers/net/ethernet/natsemi/ns83820.c
> +++ b/drivers/net/ethernet/natsemi/ns83820.c
> @@ -2208,8 +2208,13 @@ static void ns83820_remove_one(struct pci_dev *pci_dev)
>
> ns83820_disable_interrupts(dev); /* paranoia */
>
> + netif_carrier_off(ndev);
> + netif_tx_disable(ndev);
> +
> unregister_netdev(ndev);
> free_irq(dev->pci_dev->irq, ndev);
> + cancel_work_sync(&dev->tq_refill);
> +
> iounmap(dev->base);
> dma_free_coherent(&dev->pci_dev->dev, 4 * DESC_SIZE * NR_TX_DESC,
> dev->tx_descs, dev->tx_phy_descs);
> --
> 2.25.1
>

--
/Horatiu

2023-04-13 10:52:41

by Zheng Hacker

Subject: Re: [PATCH net v2] net: ethernet: fix use after free bug in ns83820_remove_one due to race condition

Horatiu Vultur <[email protected]> 于2023年4月13日周四 18:01写道：
>
> The 04/13/2023 15:14, Zheng Wang wrote:
>
> Hi Zheng,
>
> >
> > In ns83820_init_one, dev->tq_refill was bound with queue_refill.
> >
> > If irq happens, it will call ns83820_irq->ns83820_do_isr.
> > Then it invokes tasklet_schedule(&dev->rx_tasklet) to start
> > rx_action function. And rx_action will call ns83820_rx_kick
> > and finally start queue_refill function.
> >
> > If we remove the driver without finishing the work, there
> > may be a race condition between ndev, which may cause UAF
> > bug.
> >
> > CPU0 CPU1
> >
> > |queue_refill
> > ns83820_remove_one |
> > free_netdev |
> > put_device |
> > free ndev |
> > |rx_refill
> > |//use ndev
>
> Will you not have the same issue if you remove the driver after you
> schedule rx_tasklet? Because rx_action will use also ndev.
>

Hello Horatiu,

Thanks for your reply. In ns83820_remove_one, there is an invoking:

free_irq(dev->pci_dev->irq, ndev);

This will prevent the driver from handling more irq, But it couldn't prevent
the rx_tasklet from being scheduled. So I think we should add the
following code:

tasklet_kill(&dev->rx_tasklet);

after free_irq invoking. Is there anything wrong about my analysis?

Thanks again for pointing the mistake out.

Best regards,
Zheng


> >
> > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> > Signed-off-by: Zheng Wang <[email protected]>
> > ---
> > v2:
> > - cancel the work after unregister_netdev to make sure there
> > is no more request suggested by Jakub Kicinski
> > ---
> > drivers/net/ethernet/natsemi/ns83820.c | 5 +++++
> > 1 file changed, 5 insertions(+)
> >
> > diff --git a/drivers/net/ethernet/natsemi/ns83820.c b/drivers/net/ethernet/natsemi/ns83820.c
> > index 998586872599..2e84b9fcd8e9 100644
> > --- a/drivers/net/ethernet/natsemi/ns83820.c
> > +++ b/drivers/net/ethernet/natsemi/ns83820.c
> > @@ -2208,8 +2208,13 @@ static void ns83820_remove_one(struct pci_dev *pci_dev)
> >
> > ns83820_disable_interrupts(dev); /* paranoia */
> >
> > + netif_carrier_off(ndev);
> > + netif_tx_disable(ndev);
> > +
> > unregister_netdev(ndev);
> > free_irq(dev->pci_dev->irq, ndev);
> > + cancel_work_sync(&dev->tq_refill);
> > +
> > iounmap(dev->base);
> > dma_free_coherent(&dev->pci_dev->dev, 4 * DESC_SIZE * NR_TX_DESC,
> > dev->tx_descs, dev->tx_phy_descs);
> > --
> > 2.25.1
> >
>
> --
> /Horatiu

2023-04-14 14:32:30

by Horatiu Vultur

Subject: Re: [PATCH net v2] net: ethernet: fix use after free bug in ns83820_remove_one due to race condition

The 04/13/2023 18:49, Zheng Hacker wrote:

Hi Zheng,

>
> Horatiu Vultur <[email protected]> 于2023年4月13日周四 18:01写道：
> >
> > The 04/13/2023 15:14, Zheng Wang wrote:
> >
> > Hi Zheng,
> >
> > >
> > > In ns83820_init_one, dev->tq_refill was bound with queue_refill.
> > >
> > > If irq happens, it will call ns83820_irq->ns83820_do_isr.
> > > Then it invokes tasklet_schedule(&dev->rx_tasklet) to start
> > > rx_action function. And rx_action will call ns83820_rx_kick
> > > and finally start queue_refill function.
> > >
> > > If we remove the driver without finishing the work, there
> > > may be a race condition between ndev, which may cause UAF
> > > bug.
> > >
> > > CPU0 CPU1
> > >
> > > |queue_refill
> > > ns83820_remove_one |
> > > free_netdev |
> > > put_device |
> > > free ndev |
> > > |rx_refill
> > > |//use ndev
> >
> > Will you not have the same issue if you remove the driver after you
> > schedule rx_tasklet? Because rx_action will use also ndev.
> >
>
> Hello Horatiu,
>
> Thanks for your reply. In ns83820_remove_one, there is an invoking:
>
> free_irq(dev->pci_dev->irq, ndev);
>
> This will prevent the driver from handling more irq, But it couldn't prevent
> the rx_tasklet from being scheduled. So I think we should add the
> following code:
>
> tasklet_kill(&dev->rx_tasklet);
>
> after free_irq invoking. Is there anything wrong about my analysis?

I think you are right, I don't see a problem.

>
> Thanks again for pointing the mistake out.
>
> Best regards,
> Zheng
>
>
> > >
> > > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> > > Signed-off-by: Zheng Wang <[email protected]>
> > > ---
> > > v2:
> > > - cancel the work after unregister_netdev to make sure there
> > > is no more request suggested by Jakub Kicinski
> > > ---
> > > drivers/net/ethernet/natsemi/ns83820.c | 5 +++++
> > > 1 file changed, 5 insertions(+)
> > >
> > > diff --git a/drivers/net/ethernet/natsemi/ns83820.c b/drivers/net/ethernet/natsemi/ns83820.c
> > > index 998586872599..2e84b9fcd8e9 100644
> > > --- a/drivers/net/ethernet/natsemi/ns83820.c
> > > +++ b/drivers/net/ethernet/natsemi/ns83820.c
> > > @@ -2208,8 +2208,13 @@ static void ns83820_remove_one(struct pci_dev *pci_dev)
> > >
> > > ns83820_disable_interrupts(dev); /* paranoia */
> > >
> > > + netif_carrier_off(ndev);
> > > + netif_tx_disable(ndev);
> > > +
> > > unregister_netdev(ndev);
> > > free_irq(dev->pci_dev->irq, ndev);
> > > + cancel_work_sync(&dev->tq_refill);
> > > +
> > > iounmap(dev->base);
> > > dma_free_coherent(&dev->pci_dev->dev, 4 * DESC_SIZE * NR_TX_DESC,
> > > dev->tx_descs, dev->tx_phy_descs);
> > > --
> > > 2.25.1
> > >
> >
> > --
> > /Horatiu

--
/Horatiu