Verify element exists before accessing.

core/fpdfapi/fpdf_parser/fpdf_parser_utility.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 "core/fpdfapi/fpdf_parser/fpdf_parser_utility.h"
 
 #include "core/fpdfapi/fpdf_parser/include/cpdf_array.h"
 #include "core/fpdfapi/fpdf_parser/include/cpdf_dictionary.h"
@@ skipping 161 matching lines @@
     }
     case CPDF_Object::REFERENCE: {
       buf << " " << pObj->AsReference()->GetRefObjNum() << " 0 R ";
       break;
     }
     case CPDF_Object::ARRAY: {
       const CPDF_Array* p = pObj->AsArray();
       buf << "[";
       for (size_t i = 0; i < p->GetCount(); i++) {
         CPDF_Object* pElement = p->GetObjectAt(i);
-        if (pElement->GetObjNum()) {
+        if (pElement && pElement->GetObjNum()) {
           buf << " " << pElement->GetObjNum() << " 0 R";
         } else {
           buf << pElement;
         }
       }
       buf << "]";
       break;
     }
     case CPDF_Object::DICTIONARY: {
       const CPDF_Dictionary* p = pObj->AsDictionary();
@@ skipping 19 matching lines @@
       buf.AppendBlock(acc.GetData(), acc.GetSize());
       buf << "\r\nendstream";
       break;
     }
     default:
       ASSERT(FALSE);
       break;
   }
   return buf;
 }