c
static ssize_t disable_show(struct device *dev) {
    // Check the initial input pointer
    if (!dev) {
        return -EINVAL; // Or an appropriate error code 
    }

    // Check for NULL before each dereference in the chain
    if (!dev->parent || !dev->parent->parent) {
        return -EINVAL; 
    }

    struct usb_device *hdev = to_usb_device(dev->parent->parent);

    // Check the return value of to_usb_device()
    if (!hdev) {
        return -EINVAL;
    }

    struct usb_hub *hub = usb_hub_to_struct_hub(hdev);

    // Check the return value of usb_hub_to_struct_hub()
    if (!hub) {
        return -EINVAL; 
    }

    // Now safe to dereference 'hub'
    struct usb_interface *intf = to_usb_interface(hub->intfdev); 

    // ... rest of your code ...
}
