Check the validity of pointers before they are utilized

fpdfsdk/src/fpdfppo.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
  
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "../include/fpdfppo.h"
 #include "../include/fsdk_define.h"
 
 class CPDF_PageOrganizer
@@ skipping 295 matching lines @@
         
         size_t dwNewObjNum = 0;
         
         pMapPtrToPtr->Lookup((FX_LPVOID)dwObjnum, (FX_LPVOID&)dwNewObjNum);
         if(dwNewObjNum)
         {
                 return (int)dwNewObjNum;
         }
         else
         {
-                CPDF_Object* pClone  = pRef->GetDirect()->Clone();
+                CPDF_Object* pClone  = NULL;
+                if (pRef) {

[Bo Xu, 2014/09/08 00:54:24]

No need to check pRef since line 303 already check

+                    CPDF_Object* pDirect = pRef->GetDirect();
+                    if (pDirect) {
+                         pClone = pDirect->Clone();
+                    }
+                }            
                 if(!pClone)                     
                         return 0;
                 
                 if(pClone->GetType() == PDFOBJ_DICTIONARY)
                 {
                         CPDF_Dictionary* pDictClone = (CPDF_Dictionary*)pClone;
                         if(pDictClone->KeyExist("Type"))
                         {
                                 CFX_ByteString strType = pDictClone->GetString("Type");
                                 if(!FXSYS_stricmp(strType, "Pages"))
@@ skipping 128 matching lines @@
         if(!pSrcDict)
                 return FALSE;
         CPDF_Document* pDstDoc = (CPDF_Document*)dest_doc;
         CPDF_Dictionary* pDstDict = pDstDoc->GetRoot();
         if(!pDstDict)
                 return FALSE;
         pDstDict->SetAt(FX_BSTRC("ViewerPreferences"), pSrcDict->Clone(TRUE));
         return TRUE;
 }