Fix blank page issues caused by too strict check

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 "../../../include/fpdfapi/fpdf_parser.h"
 #include "../../../include/fpdfapi/fpdf_module.h"
 #include "../../../include/fpdfapi/fpdf_page.h"
 #include "../../../../third_party/numerics/safe_math.h"
@@ skipping 2415 matching lines @@
                      ((CPDF_Reference*)pLenObj)->GetRefObjNum() != objnum))) {
         len = pLenObj->GetInteger();
     }
 
     ToNextLine();
     FX_FILESIZE StreamStartPos = m_Pos;
     if (pContext) {
         pContext->m_DataStart = m_Pos;
     }
 
-    base::CheckedNumeric<FX_FILESIZE> pos = m_Pos;
-    pos += len;
-    if (pos.IsValid() && pos.ValueOrDie() < m_FileLen) {
-        m_Pos = pos.ValueOrDie();
-    } else {
-        return NULL;
-    }
-
     CPDF_CryptoHandler* pCryptoHandler = objnum == (FX_DWORD)m_MetadataObjnum ? NULL : m_pCryptoHandler;
     if (pCryptoHandler == NULL) {
+        base::CheckedNumeric<FX_FILESIZE> pos = m_Pos;
+        pos += len;
+        if (pos.IsValid() && pos.ValueOrDie() < m_FileLen) {
+            m_Pos = pos.ValueOrDie();
+        }
         GetNextWord();
         if (m_WordSize < 9 || FXSYS_memcmp32(m_WordBuffer, "endstream", 9)) {
             m_Pos = StreamStartPos;
             FX_FILESIZE offset = FindTag(FX_BSTRC("endstream"), 0);
             if (offset >= 0) {
                 FX_FILESIZE curPos = m_Pos;
                 m_Pos = StreamStartPos;
                 FX_FILESIZE endobjOffset = FindTag(FX_BSTRC("endobj"), 0);
                 if (endobjOffset < offset && endobjOffset >= 0) {
                     offset = endobjOffset;
@@ skipping 10 matching lines @@
                 }
                 len = (FX_DWORD)offset;
                 pDict->SetAtInteger(FX_BSTRC("Length"), len);
             } else {
                 m_Pos = StreamStartPos;
                 if (FindTag(FX_BSTRC("endobj"), 0) < 0) {
                     return NULL;
                 }
             }
         }
+        m_Pos = StreamStartPos;
     }
-    m_Pos = StreamStartPos;
     CPDF_Stream* pStream;
 #if defined(_FPDFAPI_MINI_) && !defined(_FXCORE_FEATURE_ALL_)
     pStream = FX_NEW CPDF_Stream(m_pFileAccess, pCryptoHandler, m_HeaderOffset + m_Pos, len, pDict, gennum);
     m_Pos += len;
 #else
     FX_LPBYTE pData = FX_Alloc(FX_BYTE, len);
     if (!pData) {
         return NULL;
     }
     ReadBlock(pData, len);
@@ skipping 1943 matching lines @@
 {
     FX_INT32 iSize = m_childNode.GetSize();
     for (FX_INT32 i = 0; i < iSize; ++i) {
         CPDF_PageNode *pNode = (CPDF_PageNode*)m_childNode[i];
         if (pNode) {
             delete pNode;
         }
     }
     m_childNode.RemoveAll();
 }