Check the hint table exists before using.

core/fpdfapi/fpdf_parser/cpdf_data_avail.cpp

Index: core/fpdfapi/fpdf_parser/cpdf_data_avail.cpp
diff --git a/core/fpdfapi/fpdf_parser/cpdf_data_avail.cpp b/core/fpdfapi/fpdf_parser/cpdf_data_avail.cpp
index f371e673ed650e9b0205576bf0953760561c53c1..c705a657aa2c7350cf9d4cfb27fbc359417a1d70 100644
--- a/core/fpdfapi/fpdf_parser/cpdf_data_avail.cpp
+++ b/core/fpdfapi/fpdf_parser/cpdf_data_avail.cpp
@@ -748,6 +748,9 @@ FX_BOOL CPDF_DataAvail::CheckHintTables(IPDF_DataAvail::DownloadHints* pHints) {
   }
 
   CPDF_Array* pHintStreamRange = pDict->GetArrayBy("H");
+  if (!pHintStreamRange)

[Lei Zhang, 2016/06/08 01:40:53]

In the bug, you mentioned this code infinite loops with the given test case. You
probably should add: m_docStatus = PDF_DATAAVAIL_ERROR - same treatment as if
the "H" key does not exist on line 739.

+    return FALSE;
+
   FX_FILESIZE szHSStart =
       pHintStreamRange->GetDirectObjectAt(0)
           ? pHintStreamRange->GetDirectObjectAt(0)->GetInteger()