Index: /trunk/src/VBox/Additions/common/VBoxGuestLib/VBoxGuestR0LibSharedFolders.c
===================================================================
--- /trunk/src/VBox/Additions/common/VBoxGuestLib/VBoxGuestR0LibSharedFolders.c	(revision 51961)
+++ /trunk/src/VBox/Additions/common/VBoxGuestLib/VBoxGuestR0LibSharedFolders.c	(revision 51962)
@@ -447,5 +447,5 @@
 {
     uint32_t            cbToRead  = *pcbBuffer;
-    uint32_t            cbData    = sizeof(VBoxSFRead) + RT_UOFFSETOF(HGCMPageListInfo, aPages[cPages]);
+    uint32_t            cbData    = (uint32_t)(sizeof(VBoxSFRead) + RT_UOFFSETOF(HGCMPageListInfo, aPages[cPages]));
     VBoxSFRead         *pData     = (VBoxSFRead *)RTMemTmpAlloc(cbData);
     HGCMPageListInfo   *pPgLst    = (HGCMPageListInfo *)(pData + 1);
@@ -527,5 +527,5 @@
     uint32_t            cbToWrite = *pcbBuffer;
     uint32_t            cPages    = RT_ALIGN_32((PhysBuffer & PAGE_OFFSET_MASK) + cbToWrite, PAGE_SIZE) >> PAGE_SHIFT;
-    uint32_t            cbData    = sizeof(VBoxSFWrite) + RT_UOFFSETOF(HGCMPageListInfo, aPages[cPages]);
+    uint32_t            cbData    = (uint32_t)(sizeof(VBoxSFWrite) + RT_UOFFSETOF(HGCMPageListInfo, aPages[cPages]));
     VBoxSFWrite        *pData     = (VBoxSFWrite *)RTMemTmpAlloc(cbData);
     HGCMPageListInfo   *pPgLst    = (HGCMPageListInfo *)(pData + 1);
@@ -575,5 +575,5 @@
 {
     uint32_t            cbToWrite = *pcbBuffer;
-    uint32_t            cbData    = sizeof(VBoxSFWrite) + RT_UOFFSETOF(HGCMPageListInfo, aPages[cPages]);
+    uint32_t            cbData    = (uint32_t)(sizeof(VBoxSFWrite) + RT_UOFFSETOF(HGCMPageListInfo, aPages[cPages]));
     VBoxSFWrite        *pData     = (VBoxSFWrite *)RTMemTmpAlloc(cbData);
     HGCMPageListInfo   *pPgLst    = (HGCMPageListInfo *)(pData + 1);