[PATCH v2] usb: renesas_usbhs: Fix use after free bug in usbhs_remove due to race condition

From: Zheng Wang
Date: Thu Apr 13 2023 - 11:44:22 EST


In usbhs_probe, &priv->notify_hotplug_work is bound with
usbhsc_notify_hotplug. It will be started then.

If we remove the driver which will call usbhs_remove
to make cleanup, there may be a unfinished work.

The possible sequence is as follows:

Fix it by finishing the work before cleanup in the usbhs_remove

CPU0 CPU1
| usbhsc_notify_hotplug
usbhs_remove |
usbhs_mod_remove |
usbhs_mod_gadget_remove |
kfree(gpriv); |
| usbhsc_hotplug
| usbhs_mod_call start
| usbhsg_start
| usbhsg_try_start
| //use gpriv

Fixes: bc57381e6347 ("usb: renesas_usbhs: use delayed_work instead of work_struct")
Signed-off-by: Zheng Wang <zyytlz.wz@xxxxxxx>
---
v2:
- beautify the format as Yoshihiro Shimoda suggested
---
drivers/usb/renesas_usbhs/common.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/usb/renesas_usbhs/common.c b/drivers/usb/renesas_usbhs/common.c
index 96f3939a65e2..17a0987ef4f5 100644
--- a/drivers/usb/renesas_usbhs/common.c
+++ b/drivers/usb/renesas_usbhs/common.c
@@ -768,6 +768,7 @@ static int usbhs_remove(struct platform_device *pdev)

dev_dbg(&pdev->dev, "usb remove\n");

+ cancel_delayed_work_sync(&priv->notify_hotplug_work);
/* power off */
if (!usbhs_get_dparam(priv, runtime_pwctrl))
usbhsc_power_ctrl(priv, 0);
--
2.25.1