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: 0807c500a1a6 ("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>

diff --git a/drivers/usb/phy/phy-fsl-usb.c b/drivers/usb/phy/phy-fsl-usb.c
index 40ac68e52cee73d168960e3588a4a0d87a88e1c1..e266a47c4d48337c50ffe80d5410baea2200b9ba 100644 (file)
--- a/drivers/usb/phy/phy-fsl-usb.c
+++ b/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);