Index: /trunk/src/VBox/Additions/common/VBoxService/VBoxServiceControlSession.cpp
===================================================================
--- /trunk/src/VBox/Additions/common/VBoxService/VBoxServiceControlSession.cpp	(revision 84159)
+++ /trunk/src/VBox/Additions/common/VBoxService/VBoxServiceControlSession.cpp	(revision 84160)
@@ -1055,4 +1055,5 @@
         pStartupInfo->psz##a_Str = RTStrAlloc(a_cb); \
         AssertPtrBreak(pStartupInfo->psz##a_Str); \
+        AssertBreak((uint32_t)a_cb == a_cb); \
         pStartupInfo->cb##a_Str  = (uint32_t)a_cb; \
     }
@@ -1146,5 +1147,7 @@
         pStartupInfoDup->psz##a_Str = (char *)RTStrDup(pStartupInfo->psz##a_Str); \
         AssertPtrBreak(pStartupInfoDup->psz##a_Str); \
-        pStartupInfoDup->cb##a_Str  = strlen(pStartupInfoDup->psz##a_Str) + 1 /* Include terminator */; \
+        size_t cbStr = strlen(pStartupInfoDup->psz##a_Str) + 1 /* Include terminator */; \
+        AssertBreak((uint32_t)cbStr == cbStr); \
+        pStartupInfoDup->cb##a_Str  = (uint32_t)cbStr; \
     }
             DUP_STR(User);