Index: /trunk/src/VBox/VMM/VMMR3/STAM.cpp
===================================================================
--- /trunk/src/VBox/VMM/VMMR3/STAM.cpp	(revision 66682)
+++ /trunk/src/VBox/VMM/VMMR3/STAM.cpp	(revision 66683)
@@ -2044,6 +2044,9 @@
      * Copy the chars to the buffer and terminate it.
      */
-    memcpy(pThis->psz, pach, cch);
-    pThis->psz += cch;
+    if (cch)
+    {
+        memcpy(pThis->psz, pach, cch);
+        pThis->psz += cch;
+    }
     *pThis->psz = '\0';
     return cch;