Index: /trunk/src/VBox/Devices/Audio/DevHDA.cpp
===================================================================
--- /trunk/src/VBox/Devices/Audio/DevHDA.cpp	(revision 82424)
+++ /trunk/src/VBox/Devices/Audio/DevHDA.cpp	(revision 82425)
@@ -2029,6 +2029,10 @@
             if (pThis->cbRirbBuf)
             {
+#ifdef IN_RING3
                 Assert(pThis->pu64RirbBuf);
-                RT_BZERO((void *)pThis->pu64RirbBuf, pThis->cbRirbBuf);
+                RT_BZERO(pThis->pu64RirbBuf, pThis->cbRirbBuf);
+#else
+                return VINF_IOM_R3_MMIO_WRITE;
+#endif
             }