I want to make a DXE_RUNTIME_DRIVER with EDK2 that hooks gRT->SetVariable so I can write stuff to memory by setting NVRAM variables through Windows (NtSetSystemEnvironmentValueEx). It always gives me a bluescreen though.

This is my code:

EFI_STATUS EFIAPI SetVariableHook(IN CHAR16 *VariableName, IN  EFI_GUID *VendorGuid, IN UINT32 Attributes, IN UINTN DataSize, IN VOID *Data) {

    if (CompareGuid(VendorGuid, &gEfiSmrkVariableGuid) && StrCmp(VariableName, gSmrkVariableName) == 0) {
        EFI_PHYSICAL_ADDRESS SMRK_PHYSICAL_ADDRESS = 0x1112323223;

        EFI_STATUS Status = gRT->ConvertPointer(0, reinterpret_cast<void**>(&SMRK_PHYSICAL_ADDRESS));

        if (EFI_ERROR(Status)) {
            return Status;
        }

        EFI_VIRTUAL_ADDRESS SMRK_ADDRESS = SMRK_PHYSICAL_ADDRESS;

        SMRK_MEMORY_TABLE *Smrk = reinterpret_cast<SMRK_MEMORY_TABLE *>(SMRK_ADDRESS);

        if (Smrk) {

            Smrk->Signature[0] = 0x53; // S
            Smrk->Signature[1] = 0x4D; // M
            Smrk->Signature[2] = 0x52; // R
            Smrk->Signature[3] = 0x4B; // K

            return EFI_SUCCESS;

        }

        return EFI_ABORTED;

    }

    return gOrigSetVariable(VariableName, VendorGuid, Attributes, DataSize, Data);

}

What do I do wrong? The error code is “UNEXPECTED KERNEL MODE TRAP”.