2023-03-13 09:49:54

by Zheng Wang

Subject: [PATCH v3] usb: gadget: udc: renesas_usb3: Fix use after free bug in renesas_usb3_remove due to race condition

In renesas_usb3_probe, &usb3->role_work is bound with
renesas_usb3_role_work. renesas_usb3_start will be called
to start the work.

If we remove the driver which will call usbhs_remove, there may be
an unfinished work. The possible sequence is as follows:

Fix it by canceling the work before cleanup in the renesas_usb3_remove

CPU0 CPU1

|renesas_usb3_role_work
renesas_usb3_remove |
usb_role_switch_unregister |
device_unregister |
kfree(sw) |
free usb3->role_sw |
| usb_role_switch_set_role
| //use usb3->role_sw

Fixes: 39facfa01c9f ("usb: gadget: udc: renesas_usb3: Add register of usb role switch")
Signed-off-by: Zheng Wang <[email protected]>
---
v3:
- modify the commit message to make it clearer suggested by Yoshihiro Shimoda
v2:
- fix typo, use clearer commit message and only cancel the UAF-related work suggested by Yoshihiro Shimoda
---
drivers/usb/gadget/udc/renesas_usb3.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/usb/gadget/udc/renesas_usb3.c b/drivers/usb/gadget/udc/renesas_usb3.c
index bee6bceafc4f..a301af66bd91 100644
--- a/drivers/usb/gadget/udc/renesas_usb3.c
+++ b/drivers/usb/gadget/udc/renesas_usb3.c
@@ -2661,6 +2661,7 @@ static int renesas_usb3_remove(struct platform_device *pdev)
debugfs_remove_recursive(usb3->dentry);
device_remove_file(&pdev->dev, &dev_attr_role);

+ cancel_work_sync(&usb3->role_work);
usb_role_switch_unregister(usb3->role_sw);

usb_del_gadget_udc(&usb3->gadget);
--
2.25.1

2023-03-13 12:56:59

by Yoshihiro Shimoda

Subject: RE: [PATCH v3] usb: gadget: udc: renesas_usb3: Fix use after free bug in renesas_usb3_remove due to race condition

Hi Zheng,

> From: Zheng Wang, Sent: Monday, March 13, 2023 6:49 PM
>
> In renesas_usb3_probe, &usb3->role_work is bound with
> renesas_usb3_role_work. renesas_usb3_start will be called
> to start the work.
>
> If we remove the driver which will call usbhs_remove, there may be
> an unfinished work. The possible sequence is as follows:
>
> Fix it by canceling the work before cleanup in the renesas_usb3_remove
>
> CPU0 CPU1
>
> |renesas_usb3_role_work
> renesas_usb3_remove |
> usb_role_switch_unregister |
> device_unregister |
> kfree(sw) |
> free usb3->role_sw |
> | usb_role_switch_set_role
> | //use usb3->role_sw
>
> Fixes: 39facfa01c9f ("usb: gadget: udc: renesas_usb3: Add register of usb role switch")
> Signed-off-by: Zheng Wang <[email protected]>

Thank you for the patch!

Reviewed-by: Yoshihiro Shimoda <[email protected]>

Best regards,
Yoshihiro Shimoda

> ---
> v3:
> - modify the commit message to make it clearer suggested by Yoshihiro Shimoda
> v2:
> - fix typo, use clearer commit message and only cancel the UAF-related work suggested by Yoshihiro Shimoda
> ---
> drivers/usb/gadget/udc/renesas_usb3.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/usb/gadget/udc/renesas_usb3.c b/drivers/usb/gadget/udc/renesas_usb3.c
> index bee6bceafc4f..a301af66bd91 100644
> --- a/drivers/usb/gadget/udc/renesas_usb3.c
> +++ b/drivers/usb/gadget/udc/renesas_usb3.c
> @@ -2661,6 +2661,7 @@ static int renesas_usb3_remove(struct platform_device *pdev)
> debugfs_remove_recursive(usb3->dentry);
> device_remove_file(&pdev->dev, &dev_attr_role);
>
> + cancel_work_sync(&usb3->role_work);
> usb_role_switch_unregister(usb3->role_sw);
>
> usb_del_gadget_udc(&usb3->gadget);
> --
> 2.25.1

2023-03-13 16:52:32

by Zheng Hacker

Subject: Re: [PATCH v3] usb: gadget: udc: renesas_usb3: Fix use after free bug in renesas_usb3_remove due to race condition

Yoshihiro Shimoda <[email protected]> 于2023年3月13日周一 20:56写道：
>
> Hi Zheng,
>
> > From: Zheng Wang, Sent: Monday, March 13, 2023 6:49 PM
> >
> > In renesas_usb3_probe, &usb3->role_work is bound with
> > renesas_usb3_role_work. renesas_usb3_start will be called
> > to start the work.
> >
> > If we remove the driver which will call usbhs_remove, there may be
> > an unfinished work. The possible sequence is as follows:
> >
> > Fix it by canceling the work before cleanup in the renesas_usb3_remove
> >
> > CPU0 CPU1
> >
> > |renesas_usb3_role_work
> > renesas_usb3_remove |
> > usb_role_switch_unregister |
> > device_unregister |
> > kfree(sw) |
> > free usb3->role_sw |
> > | usb_role_switch_set_role
> > | //use usb3->role_sw
> >
> > Fixes: 39facfa01c9f ("usb: gadget: udc: renesas_usb3: Add register of usb role switch")
> > Signed-off-by: Zheng Wang <[email protected]>
>
> Thank you for the patch!
>
> Reviewed-by: Yoshihiro Shimoda <[email protected]>
>
Thanks for the detailed review :)

Best regards,
Zheng
>
> > ---
> > v3:
> > - modify the commit message to make it clearer suggested by Yoshihiro Shimoda
> > v2:
> > - fix typo, use clearer commit message and only cancel the UAF-related work suggested by Yoshihiro Shimoda
> > ---
> > drivers/usb/gadget/udc/renesas_usb3.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/usb/gadget/udc/renesas_usb3.c b/drivers/usb/gadget/udc/renesas_usb3.c
> > index bee6bceafc4f..a301af66bd91 100644
> > --- a/drivers/usb/gadget/udc/renesas_usb3.c
> > +++ b/drivers/usb/gadget/udc/renesas_usb3.c
> > @@ -2661,6 +2661,7 @@ static int renesas_usb3_remove(struct platform_device *pdev)
> > debugfs_remove_recursive(usb3->dentry);
> > device_remove_file(&pdev->dev, &dev_attr_role);
> >
> > + cancel_work_sync(&usb3->role_work);
> > usb_role_switch_unregister(usb3->role_sw);
> >
> > usb_del_gadget_udc(&usb3->gadget);
> > --
> > 2.25.1
>