From 6f898b8053b8172f50a1351029fa97310e3f9eed Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Benjamin=20H=C3=B6glinger-Stelzer?= <nefarius@dhmx.at>
Date: Fri, 22 May 2020 21:57:43 +0200
Subject: [PATCH] Added duplicate device check

---
 sys/Driver.cpp | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/sys/Driver.cpp b/sys/Driver.cpp
index ac2e697..6d42c2f 100644
--- a/sys/Driver.cpp
+++ b/sys/Driver.cpp
@@ -114,6 +114,7 @@ NTSTATUS Bus_EvtDeviceAdd(IN WDFDRIVER Driver, IN PWDFDEVICE_INIT DeviceInit)
     WDF_OBJECT_ATTRIBUTES       fdoAttributes;
     WDF_OBJECT_ATTRIBUTES       fileHandleAttributes;
     PFDO_DEVICE_DATA            pFDOData;
+    PWSTR                       pSymbolicNameList;
 
     UNREFERENCED_PARAMETER(Driver);
 
@@ -121,6 +122,46 @@ NTSTATUS Bus_EvtDeviceAdd(IN WDFDRIVER Driver, IN PWDFDEVICE_INIT DeviceInit)
 
     TraceEvents(TRACE_LEVEL_INFORMATION, TRACE_DRIVER, "%!FUNC! Entry");
 
+#pragma region Check for duplicated FDO
+
+    //
+    // Note: this could be avoided if converted to non-PNP driver
+    // and use of named device object. Food for thought for future.
+    // 
+	
+    status = IoGetDeviceInterfaces(
+        &GUID_DEVINTERFACE_BUSENUM_VIGEM, 
+        NULL,
+        0, // Important!
+        &pSymbolicNameList
+    );
+    if (NT_SUCCESS(status))
+    {
+	    const bool deviceAlreadyExists = (0 != *pSymbolicNameList);
+	    ExFreePool(pSymbolicNameList);
+
+	    if (deviceAlreadyExists)
+	    {
+            TraceEvents(TRACE_LEVEL_ERROR,
+                TRACE_DRIVER,
+                "Device with interface GUID {%!GUID!} already exists (%ws)",
+                &GUID_DEVINTERFACE_BUSENUM_VIGEM,
+                pSymbolicNameList
+            );
+
+            return STATUS_RESOURCE_IN_USE;
+	    }
+    }
+    else
+    {
+	    TraceEvents(TRACE_LEVEL_WARNING,
+	                TRACE_DRIVER,
+	                "IoGetDeviceInterfaces failed with status %!STATUS!",
+	                status);
+    }
+
+#pragma endregion
+
     WdfDeviceInitSetDeviceType(DeviceInit, FILE_DEVICE_BUS_EXTENDER);
     // More than one process may talk to the bus at the same time
     WdfDeviceInitSetExclusive(DeviceInit, FALSE);