Send new IRP

[Jacek Chodak]

Hi


I'm working on a mouse filter driver. The filter send new IRP to the
driver, but the driver (mouclass) send exception 0xC0000005:
STATUS_ACCESS_VIOLATION (a memory access violation occurred).

Here is a piece of source code:

//---------------------------------------------------

NTSTATUS Dispatch(IN PDEVICE_OBJECT DeviceObject, IN PIRP Irp)
{

..
..
..

//Create buffer
Buffer =
ExAllocatePoolWithTag(NonPagedPool,sizeof(MOUSE_INPUT_DATA),'BHVM');
//call function
status = MakeAsynchronousRequest(MouFilterDevice, Buffer,
sizeof(MOUSE_INPUT_DATA));

..
..
..
}


NTSTATUS
MakeAsynchronousRequest (
PDEVICE_OBJECT TopOfDeviceStack,
PVOID WriteBuffer,
ULONG NumBytes
)
/*++
Arguments:

TopOfDeviceStack -

WriteBuffer - Buffer to be sent to the TopOfDeviceStack.

NumBytes - Size of buffer to be sent to the TopOfDeviceStack.

--*/
{
NTSTATUS status;
PIRP irp;
LARGE_INTEGER startingOffset;
PIO_STACK_LOCATION nextStack;
PVOID context;

startingOffset.QuadPart = (LONGLONG) 0;

irp = IoBuildAsynchronousFsdRequest(
IRP_MJ_READ,
TopOfDeviceStack,
WriteBuffer,
NumBytes,
&startingOffset, // Optional
NULL
);

if (NULL == irp) {

return STATUS_INSUFFICIENT_RESOURCES;
}

context = ExAllocatePoolWithTag(NonPagedPool, sizeof(ULONG_PTR),
'ITag');

if (NULL == context) {
IoFreeIrp(irp);
return STATUS_INSUFFICIENT_RESOURCES;
}


IoSetCompletionRoutine(irp,
MakeAsynchronousRequestCompletion,
context,
TRUE,
TRUE,
TRUE);


nextStack = IoGetNextIrpStackLocation(irp);
//
// Change the MajorFunction code to something appropriate.
//
nextStack->MajorFunction = IRP_MJ_READ;
nextStack->Parameters.Read.Length = sizeof(MOUSE_INPUT_DATA);
//irp->IoStatus.Status = STATUS_SUCCESS;
//irp->IoStatus.Information = sizeof(MOUSE_INPUT_DATA);



status = IoCallDriver(TopOfDeviceStack, irp);


return STATUS_SUCCESS;
}

NTSTATUS
MakeAsynchronousRequestCompletion(
IN PDEVICE_OBJECT DeviceObject,
IN PIRP Irp,
IN PVOID Context
)
{
PMDL mdl, nextMdl;
PMOUSE_INPUT_DATA MouData;


MouData = (PMOUSE_INPUT_DATA)Irp->AssociatedIrp.SystemBuffer;
MouData->Flags = MOUSE_MOVE_RELATIVE;
MouData->LastX = 10;





if(Irp->AssociatedIrp.SystemBuffer && (Irp->Flags &
IRP_DEALLOCATE_BUFFER) ) {
ExFreePool(Irp->AssociatedIrp.SystemBuffer);
}

else if (Irp->MdlAddress != NULL) {
for (mdl = Irp->MdlAddress; mdl != NULL; mdl = nextMdl) {
nextMdl = mdl->Next;
MmUnlockPages( mdl ); IoFreeMdl( mdl ); // This function
will also unmap pages.
}
Irp->MdlAddress = NULL;
}

if(Context) {
ExFreePool(Context);
}



IoFreeIrp(Irp);

return STATUS_MORE_PROCESSING_REQUIRED;
}

//---------------------------------------------------

Whot I'm doing wrong ?

Thanks in advance.