2023-03-07 16:48:13

by Zheng Wang

Subject: [PATCH] memstick: r592: Fix UAF bug in r592_remove due to race condition

In r592_probe, dev->detect_timer was bound with r592_detect_timer.
In r592_irq function, the timer function will be invoked by mod_timer.

If we remove the module which will call hantro_release to make cleanup,
there may be a unfinished work. The possible sequence is as follows,
which will cause a typical UAF bug.

Fix it by canceling the work before cleanup in r592_remove.

CPU0 CPU1

|r592_detect_timer
r592_remove |
memstick_free_host|
put_device; |
kfree(host); |
|
| queue_work
| &host->media_checker //use

Signed-off-by: Zheng Wang <[email protected]>
---
drivers/memstick/host/r592.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/memstick/host/r592.c b/drivers/memstick/host/r592.c
index 1d35d147552d..2bfa7eaae80a 100644
--- a/drivers/memstick/host/r592.c
+++ b/drivers/memstick/host/r592.c
@@ -829,7 +829,7 @@ static void r592_remove(struct pci_dev *pdev)
/* Stop the processing thread.
That ensures that we won't take any more requests */
kthread_stop(dev->io_thread);
-
+ del_timer_sync(&dev->detect_timer);
r592_enable_device(dev, false);

while (!error && dev->req) {
--
2.25.1

2023-03-09 15:05:46

by Ulf Hansson

Subject: Re: [PATCH] memstick: r592: Fix UAF bug in r592_remove due to race condition

On Tue, 7 Mar 2023 at 17:44, Zheng Wang <[email protected]> wrote:
>
> In r592_probe, dev->detect_timer was bound with r592_detect_timer.
> In r592_irq function, the timer function will be invoked by mod_timer.
>
> If we remove the module which will call hantro_release to make cleanup,
> there may be a unfinished work. The possible sequence is as follows,
> which will cause a typical UAF bug.
>
> Fix it by canceling the work before cleanup in r592_remove.
>
> CPU0 CPU1
>
> |r592_detect_timer
> r592_remove |
> memstick_free_host|
> put_device; |
> kfree(host); |
> |
> | queue_work
> | &host->media_checker //use
>
> Signed-off-by: Zheng Wang <[email protected]>

Applied for next, thanks!

Kind regards
Uffe


> ---
> drivers/memstick/host/r592.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/memstick/host/r592.c b/drivers/memstick/host/r592.c
> index 1d35d147552d..2bfa7eaae80a 100644
> --- a/drivers/memstick/host/r592.c
> +++ b/drivers/memstick/host/r592.c
> @@ -829,7 +829,7 @@ static void r592_remove(struct pci_dev *pdev)
> /* Stop the processing thread.
> That ensures that we won't take any more requests */
> kthread_stop(dev->io_thread);
> -
> + del_timer_sync(&dev->detect_timer);
> r592_enable_device(dev, false);
>
> while (!error && dev->req) {
> --
> 2.25.1
>

2023-03-10 16:25:24

by Zheng Hacker

Subject: Re: [PATCH] memstick: r592: Fix UAF bug in r592_remove due to race condition

Ulf Hansson <[email protected]> 于2023年3月9日周四 23:02写道：
>
> On Tue, 7 Mar 2023 at 17:44, Zheng Wang <[email protected]> wrote:
> >
> > In r592_probe, dev->detect_timer was bound with r592_detect_timer.
> > In r592_irq function, the timer function will be invoked by mod_timer.
> >
> > If we remove the module which will call hantro_release to make cleanup,
> > there may be a unfinished work. The possible sequence is as follows,
> > which will cause a typical UAF bug.
> >
> > Fix it by canceling the work before cleanup in r592_remove.
> >
> > CPU0 CPU1
> >
> > |r592_detect_timer
> > r592_remove |
> > memstick_free_host|
> > put_device; |
> > kfree(host); |
> > |
> > | queue_work
> > | &host->media_checker //use
> >
> > Signed-off-by: Zheng Wang <[email protected]>
>
> Applied for next, thanks!
>
Sorry for my late reply and thanks for your effort!

Best regards,
Zheng
>
>
> > ---
> > drivers/memstick/host/r592.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/memstick/host/r592.c b/drivers/memstick/host/r592.c
> > index 1d35d147552d..2bfa7eaae80a 100644
> > --- a/drivers/memstick/host/r592.c
> > +++ b/drivers/memstick/host/r592.c
> > @@ -829,7 +829,7 @@ static void r592_remove(struct pci_dev *pdev)
> > /* Stop the processing thread.
> > That ensures that we won't take any more requests */
> > kthread_stop(dev->io_thread);
> > -
> > + del_timer_sync(&dev->detect_timer);
> > r592_enable_device(dev, false);
> >
> > while (!error && dev->req) {
> > --
> > 2.25.1
> >