2023-03-11 16:14:05

by Zheng Wang

Subject: [PATCH v2] 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.

to make cleanup, 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]>
---
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 08:28:28

by Yoshihiro Shimoda

Subject: RE: [PATCH v2] usb: gadget: udc: renesas_usb3: Fix use after free bug in renesas_usb3_remove due to race condition

Hi Zheng,

> From: Zheng Wang, Sent: Sunday, March 12, 2023 1:13 AM
>
> In renesas_usb3_probe, &usb3->role_work is bound with
> renesas_usb3_role_work. renesas_usb3_start will be called
> to start the work.
>
> to make cleanup, there may be an unfinished work. The possible
> sequence is as follows:

Why do you remove the following description on this v2 patch?
-----
If we remove the driver which will call usbhs_remove
-----
I think this description is helpful to understand.

Best regards,
Yoshihiro Shimoda

> 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]>
> ---
> 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 08:51:43

by Zheng Hacker

Subject: Re: [PATCH v2] 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 16:28写道：
>
> Hi Zheng,
>
> > From: Zheng Wang, Sent: Sunday, March 12, 2023 1:13 AM
> >
> > In renesas_usb3_probe, &usb3->role_work is bound with
> > renesas_usb3_role_work. renesas_usb3_start will be called
> > to start the work.
> >
> > to make cleanup, there may be an unfinished work. The possible
> > sequence is as follows:
>
> Why do you remove the following description on this v2 patch?
> -----
> If we remove the driver which will call usbhs_remove
> -----
> I think this description is helpful to understand.
>

Sorry I misunderstood you previous response for my poor English. Will
append it again in the next version.

Best reagrds,
Zheng

>
> > 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]>
> > ---
> > 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
>