ObReferenceObjectByHandle Bugcheck, Memory Access Violation

I am working on a project to dynamically disable the keyboard. I have written a driver which attempts to obtain the keyboards physical device object then call IoInvalidateDeviceState with it but I am having a problem getting its physical device object. Whenever I try to call ObReferenceObjectByHandle with the handle to the device object, a bugcheck occurs and the error is a memory access violation. Here is my source code:

#include "ntifs.h"
#include "wdm.h" 
#include "ntstrsafe.h"
#pragma comment(lib, "ntstrsafe.lib")

VOID DriverUnloadRoutine(__in PDRIVER_OBJECT DriverObject);

DRIVER_INITIALIZE DriverEntry;
NTSTATUS DriverEntry( 
__in struct _DRIVER_OBJECT  *DriverObject,
__in PUNICODE_STRING  RegistryPath 
)
{
UNICODE_STRING keybdname;
FILE_OBJECT * keybdfo;
DEVICE_OBJECT * keybddo;
HANDLE hpdo;
FILE_OBJECT * 开发者_JAVA技巧pdofo;
DEVICE_OBJECT * pdo;

DriverObject->DriverUnload = DriverUnloadRoutine;

RtlInitUnicodeString(&keybdname,L"\\Device\\KeyboardClass0");
IoGetDeviceObjectPointer(&keybdname,GENERIC_ALL,&keybdfo,&keybddo);
ObOpenObjectByPointer(&keybddo,OBJ_KERNEL_HANDLE,0,0,0,KernelMode,&hpdo);
ObReferenceObjectByHandle(hpdo,FILE_ALL_ACCESS,*IoFileObjectType,KernelMode,&pdofo,NULL);
pdo = IoGetRelatedDeviceObject(&pdofo);
IoInvalidateDeviceState(&pdo);

return 0;  
}

VOID DriverUnloadRoutine(
    __in PDRIVER_OBJECT DriverObject
    )
{

}

I realize this is probably not the best way to accomplish this (maybe even the worst), but the only two other ways I know of are unplugging the keyboard or installing a filter driver, which would require a reboot. If there is another way to do this, informing me of it would be great. Thanks in advance for the help!

My guess would be, that one of your functions you are calling does return a error value, and does not fill out the according structure.

I would go about disabling the keyboard by looking at the SetupApi or the CfgMgr32 functions.

The "devcon" wdk sample should contain the code to disable a device from user mode.