usb: phy: fsl-usb: Fix use-after-free in delayed work during device removal

The delayed work item otg_event is initialized in fsl_otg_conf() and
scheduled under two conditions:
1. When a host controller binds to the OTG controller.
2. When the USB ID pin state changes (cable insertion/removal).

A race condition occurs when the device is removed via fsl_otg_remove():
the fsl_otg instance may be freed while the delayed work is still pending
or executing. This leads to use-after-free when the work function
fsl_otg_event() accesses the already freed memory.

The problematic scenario:

(detach thread)            | (delayed work)
fsl_otg_remove()           |
  kfree(fsl_otg_dev) //FREE| fsl_otg_event()
                           |   og = container_of(...) //USE
                           |   og-> //USE

Fix this by calling disable_delayed_work_sync() in fsl_otg_remove()
before deallocating the fsl_otg structure. This ensures the delayed work
is properly canceled and completes execution prior to memory deallocation.

This bug was identified through static analysis.

Fixes: 0807c500a1 ("USB: add Freescale USB OTG Transceiver driver")
Cc: stable <stable@kernel.org>
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Link: https://patch.msgid.link/20251205034831.12846-1-duoming@zju.edu.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/phy/phy-fsl-usb.c

@@ -988,6 +988,7 @@ static void fsl_otg_remove(struct platform_device *pdev)
 {
 	struct fsl_usb2_platform_data *pdata = dev_get_platdata(&pdev->dev);
 
+	disable_delayed_work_sync(&fsl_otg_dev->otg_event);
 	usb_remove_phy(&fsl_otg_dev->phy);
 	free_irq(fsl_otg_dev->irq, fsl_otg_dev);