In renesas_usb3_probe, 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.
Note that removing a driver is a root-only operation, and should never
happen.
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
This bug was found by static analysis.
Fixes: 39facfa01c9f ("usb: gadget: udc: renesas_usb3: Add register of usb role switch")
Signed-off-by: Zheng Wang <[email protected]>
Reviewed-by: Yoshihiro Shimoda <[email protected]>
---
v8:
- replace | with spaces to make line up suggested by Greg KH
v7:
- add more details about how the bug was found suggested by Shuah
v6:
- beautify the format and add note suggested by Greg KH
v5:
- fix typo
v4:
- add Reviewed-by label and resubmit v4 suggested by Greg KH
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
On Fri, Mar 17, 2023 at 02:16:23AM +0800, Zheng Wang wrote:
> In renesas_usb3_probe, 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.
>
> Note that removing a driver is a root-only operation, and should never
> happen.
>
> 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
No line at all?
Greg KH <[email protected]> 于2023年3月17日周五 03:07写道：
>
> On Fri, Mar 17, 2023 at 02:16:23AM +0800, Zheng Wang wrote:
> > In renesas_usb3_probe, 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.
> >
> > Note that removing a driver is a root-only operation, and should never
> > happen.
> >
> > 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
>
> No line at all?
>
Sorry, I'll remove the empty line. And I think there are other ways to
trigger device's remove like directly unpluging the USB device if
accessible. I think we nee to append this msg in the next version.
Best regards,
Zheng