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

[Zheng Wang]

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 module which will call renesas_usb3_remove
  to make cleanup, there may be a unfinished work. The possible
  sequence is as follows:

Fix it by canceling the work before cleanup in the renesas_usb3_remove

CPU0                  CPUc1

                    |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 <zyytlz.wz@xxxxxxx>
---
 drivers/usb/gadget/udc/renesas_usb3.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/usb/gadget/udc/renesas_usb3.c b/drivers/usb/gadget/udc/renesas_usb3.c
index bee6bceafc4f..23b5f1706d25 100644
--- a/drivers/usb/gadget/udc/renesas_usb3.c
+++ b/drivers/usb/gadget/udc/renesas_usb3.c
@@ -2658,6 +2658,8 @@ static int renesas_usb3_remove(struct platform_device *pdev)
 {
 	struct renesas_usb3 *usb3 = platform_get_drvdata(pdev);
 
+	cancel_work_sync(&usb3->extcon_work);
+	cancel_work_sync(&usb3->role_work);
 	debugfs_remove_recursive(usb3->dentry);
 	device_remove_file(&pdev->dev, &dev_attr_role);
 
-- 
2.25.1