2023-03-09 17:04:34

by Zheng Wang

Subject: [PATCH net] xirc2ps_cs: Fix use after free bug in xirc2ps_detach

In xirc2ps_probe, the local->tx_timeout_task was bounded
with xirc2ps_tx_timeout_task. When timeout occurs,
it will call xirc_tx_timeout->schedule_work to start the
work.

When we call xirc2ps_detach to remove the driver, there
may be a sequence as follows:

Fix it by finishing the work before cleanup in xirc2ps_detach

CPU0 CPU1

|xirc2ps_tx_timeout_task
xirc2ps_detach |
free_netdev |
kfree(dev); |
|
| do_reset
| //use

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Zheng Wang <[email protected]>
---
drivers/net/ethernet/xircom/xirc2ps_cs.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/xircom/xirc2ps_cs.c b/drivers/net/ethernet/xircom/xirc2ps_cs.c
index 894e92ef415b..ea7b06f75691 100644
--- a/drivers/net/ethernet/xircom/xirc2ps_cs.c
+++ b/drivers/net/ethernet/xircom/xirc2ps_cs.c
@@ -503,7 +503,10 @@ static void
xirc2ps_detach(struct pcmcia_device *link)
{
struct net_device *dev = link->priv;
-
+ struct local_info *local;
+
+ local = netdev_priv(dev);
+ cancel_work_sync(&local->tx_timeout_task)
dev_dbg(&link->dev, "detach\n");

unregister_netdev(dev);
--
2.25.1

2023-03-10 13:59:17

by Simon Horman

Subject: Re: [PATCH net] xirc2ps_cs: Fix use after free bug in xirc2ps_detach

On Fri, Mar 10, 2023 at 12:57:29AM +0800, Zheng Wang wrote:
> In xirc2ps_probe, the local->tx_timeout_task was bounded
> with xirc2ps_tx_timeout_task. When timeout occurs,
> it will call xirc_tx_timeout->schedule_work to start the
> work.
>
> When we call xirc2ps_detach to remove the driver, there
> may be a sequence as follows:
>
> Fix it by finishing the work before cleanup in xirc2ps_detach
>
> CPU0 CPU1
>
> |xirc2ps_tx_timeout_task
> xirc2ps_detach |
> free_netdev |
> kfree(dev); |
> |
> | do_reset
> | //use
>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Zheng Wang <[email protected]>
> ---
> drivers/net/ethernet/xircom/xirc2ps_cs.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/xircom/xirc2ps_cs.c b/drivers/net/ethernet/xircom/xirc2ps_cs.c
> index 894e92ef415b..ea7b06f75691 100644
> --- a/drivers/net/ethernet/xircom/xirc2ps_cs.c
> +++ b/drivers/net/ethernet/xircom/xirc2ps_cs.c
> @@ -503,7 +503,10 @@ static void
> xirc2ps_detach(struct pcmcia_device *link)
> {
> struct net_device *dev = link->priv;
> -
> + struct local_info *local;
> +
> + local = netdev_priv(dev);
> + cancel_work_sync(&local->tx_timeout_task)
> dev_dbg(&link->dev, "detach\n");
>
> unregister_netdev(dev);

This doesn't compile.
Also, the indentation is incorrect.

I think what should have been posted is:

diff --git a/drivers/net/ethernet/xircom/xirc2ps_cs.c b/drivers/net/ethernet/xircom/xirc2ps_cs.c
index 894e92ef415b..b607fea486ab 100644
--- a/drivers/net/ethernet/xircom/xirc2ps_cs.c
+++ b/drivers/net/ethernet/xircom/xirc2ps_cs.c
@@ -503,7 +503,10 @@ static void
xirc2ps_detach(struct pcmcia_device *link)
{
struct net_device *dev = link->priv;
+ struct local_info *local;

+ local = netdev_priv(dev);
+ cancel_work_sync(&local->tx_timeout_task);
dev_dbg(&link->dev, "detach\n");

unregister_netdev(dev);

2023-03-10 16:55:20

by Zheng Hacker

Subject: Re: [PATCH net] xirc2ps_cs: Fix use after free bug in xirc2ps_detach

Simon Horman <[email protected]> 于2023年3月10日周五 21:59写道：
>
> On Fri, Mar 10, 2023 at 12:57:29AM +0800, Zheng Wang wrote:
> > In xirc2ps_probe, the local->tx_timeout_task was bounded
> > with xirc2ps_tx_timeout_task. When timeout occurs,
> > it will call xirc_tx_timeout->schedule_work to start the
> > work.
> >
> > When we call xirc2ps_detach to remove the driver, there
> > may be a sequence as follows:
> >
> > Fix it by finishing the work before cleanup in xirc2ps_detach
> >
> > CPU0 CPU1
> >
> > |xirc2ps_tx_timeout_task
> > xirc2ps_detach |
> > free_netdev |
> > kfree(dev); |
> > |
> > | do_reset
> > | //use
> >
> > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> > Signed-off-by: Zheng Wang <[email protected]>
> > ---
> > drivers/net/ethernet/xircom/xirc2ps_cs.c | 5 ++++-
> > 1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/ethernet/xircom/xirc2ps_cs.c b/drivers/net/ethernet/xircom/xirc2ps_cs.c
> > index 894e92ef415b..ea7b06f75691 100644
> > --- a/drivers/net/ethernet/xircom/xirc2ps_cs.c
> > +++ b/drivers/net/ethernet/xircom/xirc2ps_cs.c
> > @@ -503,7 +503,10 @@ static void
> > xirc2ps_detach(struct pcmcia_device *link)
> > {
> > struct net_device *dev = link->priv;
> > -
> > + struct local_info *local;
> > +
> > + local = netdev_priv(dev);
> > + cancel_work_sync(&local->tx_timeout_task)
> > dev_dbg(&link->dev, "detach\n");
> >
> > unregister_netdev(dev);
>
> This doesn't compile.
> Also, the indentation is incorrect.

Sorry for my mistake. I was hurried to report the issue and ignored
the compile test.

>
> I think what should have been posted is:

Yes, will correct it in the next version of patch.

Best regards,
Zheng

>
> diff --git a/drivers/net/ethernet/xircom/xirc2ps_cs.c b/drivers/net/ethernet/xircom/xirc2ps_cs.c
> index 894e92ef415b..b607fea486ab 100644
> --- a/drivers/net/ethernet/xircom/xirc2ps_cs.c
> +++ b/drivers/net/ethernet/xircom/xirc2ps_cs.c
> @@ -503,7 +503,10 @@ static void
> xirc2ps_detach(struct pcmcia_device *link)
> {
> struct net_device *dev = link->priv;
> + struct local_info *local;
>
> + local = netdev_priv(dev);
> + cancel_work_sync(&local->tx_timeout_task);
> dev_dbg(&link->dev, "detach\n");
>
> unregister_netdev(dev);