Loose checking for trailer's size field

core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.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/include/fpdfapi/fpdf_parser.h"
 
 #include <algorithm>
 #include <memory>
@@ skipping 374 matching lines @@
 FX_BOOL CPDF_Parser::LoadAllCrossRefV4(FX_FILESIZE xrefpos) {
   if (!LoadCrossRefV4(xrefpos, 0, TRUE)) {
     return FALSE;
   }
   m_pTrailer = LoadTrailerV4();
   if (!m_pTrailer) {
     return FALSE;
   }
 
   int32_t xrefsize = GetDirectInteger(m_pTrailer, "Size");
-  if (xrefsize <= 0 || xrefsize > kMaxXRefSize) {
-    return FALSE;
+  if (xrefsize > 0 && xrefsize <= kMaxXRefSize) {
+    ShrinkObjectMap(xrefsize);
+    m_V5Type.SetSize(xrefsize);
   }
-  ShrinkObjectMap(xrefsize);
-  m_V5Type.SetSize(xrefsize);
+
   CFX_FileSizeArray CrossRefList;
   CFX_FileSizeArray XRefStreamList;
   CrossRefList.Add(xrefpos);
   XRefStreamList.Add(GetDirectInteger(m_pTrailer, "XRefStm"));
 
   std::set<FX_FILESIZE> seen_xrefpos;
   seen_xrefpos.insert(xrefpos);
   // When |m_pTrailer| doesn't have Prev entry or Prev entry value is not
   // numerical, GetDirectInteger() returns 0. Loading will end.
   xrefpos = GetDirectInteger(m_pTrailer, "Prev");
@@ skipping 4596 matching lines @@
   if (!m_pLinearizedDict)
     return -1;
   CPDF_Array* pRange = m_pLinearizedDict->GetArray("H");
   if (!pRange)
     return -1;
   CPDF_Object* pStreamLen = pRange->GetElementValue(1);
   if (!pStreamLen)
     return -1;
   return pStreamLen->GetInteger();
 }