Index: /trunk/src/VBox/HostServices/SharedClipboard/VBoxSharedClipboardSvc-x11.cpp
===================================================================
--- /trunk/src/VBox/HostServices/SharedClipboard/VBoxSharedClipboardSvc-x11.cpp	(revision 81151)
+++ /trunk/src/VBox/HostServices/SharedClipboard/VBoxSharedClipboardSvc-x11.cpp	(revision 81152)
@@ -168,4 +168,5 @@
 
     PSHCLCONTEXT pCtx = pClient->State.pCtx;
+    AssertPtr(pCtx);
 
     /* Drop the reference to the client, in case it is still there.  This
@@ -173,8 +174,4 @@
      * immediately. */
     pCtx->fShuttingDown = true;
-
-    /* If there is a currently pending request, release it immediately. */
-    SHCLDATABLOCK dataBlock = { 0, NULL, 0 };
-    ShClSvcImplWriteData(pClient, NULL, &dataBlock);
 
     int rc = ClipStopX11(pCtx->pBackend);
@@ -304,4 +301,8 @@
                          PSHCLCLIENTCMDCTX pCmdCtx, PSHCLDATABLOCK pData)
 {
+    AssertPtrReturn(pClient, VERR_INVALID_POINTER);
+    AssertPtrReturn(pCmdCtx, VERR_INVALID_POINTER);
+    AssertPtrReturn(pData,   VERR_INVALID_POINTER);
+
     LogFlowFunc(("pClient=%p, pv=%p, cb=%RU32, uFormat=%02X\n",
                  pClient, pData->pvData, pData->cbData, pData->uFormat));
Index: /trunk/src/VBox/HostServices/SharedClipboard/VBoxSharedClipboardSvc.cpp
===================================================================
--- /trunk/src/VBox/HostServices/SharedClipboard/VBoxSharedClipboardSvc.cpp	(revision 81151)
+++ /trunk/src/VBox/HostServices/SharedClipboard/VBoxSharedClipboardSvc.cpp	(revision 81152)
@@ -900,4 +900,8 @@
                           PSHCLDATABLOCK pData)
 {
+    AssertPtrReturn(pClient, VERR_INVALID_POINTER);
+    AssertPtrReturn(pCmdCtx, VERR_INVALID_POINTER);
+    AssertPtrReturn(pData,   VERR_INVALID_POINTER);
+
     SHCLEVENTID uEvent;
     if (pClient->State.uProtocolVer == 0)
@@ -1111,6 +1115,4 @@
 static DECLCALLBACK(int) svcDisconnect(void *, uint32_t u32ClientID, void *pvClient)
 {
-    RT_NOREF(u32ClientID, pvClient);
-
     LogFunc(("u32ClientID=%RU32\n", u32ClientID));