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

[Zheng Hacker]

Simon Horman <simon.horman@xxxxxxxxxxxx> 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 <zyytlz.wz@xxxxxxx>
> > ---
> >  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);