Fix blank page issues caused by too strict checkchromium/2250chromium/2249chromium/2248chromium/2247chromium/2246chromium/2245chromium/2244chromium/2243chromium/2242chromium/2241chromium/2240chromium/2239chromium/2238chromium/2237

Before this fix, PDF parser aborts the parsering process when detecting an error.
For this case, PDF parser just gives up parsering when it detects that the length of
image stream is incorrect. The solution to this case is to find the tag "endstream"
and "endobj" to calculate the length rather than aborting the parsering process.

BUG=433339
R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/743263002

1 files changed, 6 insertions, 9 deletions

diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
index 029913458a..86ffae2f6e 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
@@ -2433,16 +2433,13 @@ CPDF_Stream* CPDF_SyntaxParser::ReadStream(CPDF_Dictionary* pDict, PARSE_CONTEXT
         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;
@@ -2473,8 +2470,8 @@ CPDF_Stream* CPDF_SyntaxParser::ReadStream(CPDF_Dictionary* pDict, PARSE_CONTEXT
                 }
             }
         }
+        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);