From 5b13e1dc5770b73295f0c4a61c699a10eb7922e6 Mon Sep 17 00:00:00 2001
From: thestig <thestig@chromium.org>
Date: Fri, 19 Aug 2016 12:04:05 -0700
Subject: Add a fuzzer for CPDF_HintTables.

BUG=636559

Review-Url: https://codereview.chromium.org/2255083004
---
 core/fpdfapi/fpdf_parser/cpdf_hint_tables.cpp | 19 ++++++++++++++++---
 core/fpdfapi/fpdf_parser/cpdf_hint_tables.h   | 15 ++++++++-------
 2 files changed, 24 insertions(+), 10 deletions(-)

(limited to 'core/fpdfapi')

diff --git a/core/fpdfapi/fpdf_parser/cpdf_hint_tables.cpp b/core/fpdfapi/fpdf_parser/cpdf_hint_tables.cpp
index 4d48ab4bfa..f1e74dc6bc 100644
--- a/core/fpdfapi/fpdf_parser/cpdf_hint_tables.cpp
+++ b/core/fpdfapi/fpdf_parser/cpdf_hint_tables.cpp
@@ -60,6 +60,8 @@ bool CPDF_HintTables::ReadPageHintTable(CFX_BitStream* hStream) {
 
   // Item 1: The least number of objects in a page.
   uint32_t dwObjLeastNum = hStream->GetBits(32);
+  if (!dwObjLeastNum)
+    return FALSE;
 
   // Item 2: The location of the first page's page object.
   uint32_t dwFirstObjLoc = hStream->GetBits(32);
@@ -78,13 +80,19 @@ bool CPDF_HintTables::ReadPageHintTable(CFX_BitStream* hStream) {
   // Item 3: The number of bits needed to represent the difference
   // between the greatest and least number of objects in a page.
   uint32_t dwDeltaObjectsBits = hStream->GetBits(16);
+  if (!dwDeltaObjectsBits)
+    return FALSE;
 
   // Item 4: The least length of a page in bytes.
   uint32_t dwPageLeastLen = hStream->GetBits(32);
+  if (!dwPageLeastLen)
+    return FALSE;
 
   // Item 5: The number of bits needed to represent the difference
   // between the greatest and least length of a page, in bytes.
   uint32_t dwDeltaPageLenBits = hStream->GetBits(16);
+  if (!dwDeltaPageLenBits)
+    return FALSE;
 
   // Skip Item 6, 7, 8, 9 total 96 bits.
   hStream->SkipBits(96);
@@ -96,12 +104,16 @@ bool CPDF_HintTables::ReadPageHintTable(CFX_BitStream* hStream) {
   // Item 11: The number of bits needed to represent the numerically
   // greatest shared object identifier used by the pages.
   uint32_t dwSharedIdBits = hStream->GetBits(16);
+  if (!dwSharedObjBits)
+    return FALSE;
 
   // Item 12: The number of bits needed to represent the numerator of
   // the fractional position for each shared object reference. For each
   // shared object referenced from a page, there is an indication of
   // where in the page's content stream the object is first referenced.
   uint32_t dwSharedNumeratorBits = hStream->GetBits(16);
+  if (!dwSharedIdBits)
+    return FALSE;
 
   // Item 13: Skip Item 13 which has 16 bits.
   hStream->SkipBits(16);
@@ -113,7 +125,7 @@ bool CPDF_HintTables::ReadPageHintTable(CFX_BitStream* hStream) {
     return false;
 
   const int nPages = GetNumberOfPages();
-  if (nPages < 1)
+  if (nPages < 1 || nPages >= FPDF_PAGE_MAX_NUM)
     return false;
 
   const uint32_t dwPages = pdfium::base::checked_cast<uint32_t>(nPages);
@@ -136,13 +148,14 @@ bool CPDF_HintTables::ReadPageHintTable(CFX_BitStream* hStream) {
   if (!CanReadFromBitStream(hStream, required_bits))
     return false;
 
-  CFX_ArrayTemplate<uint32_t> dwPageLenArray;
+  std::vector<uint32_t> dwPageLenArray;
   for (int i = 0; i < nPages; ++i) {
     FX_SAFE_UINT32 safePageLen = hStream->GetBits(dwDeltaPageLenBits);
     safePageLen += dwPageLeastLen;
     if (!safePageLen.IsValid())
       return false;
-    dwPageLenArray.Add(safePageLen.ValueOrDie());
+
+    dwPageLenArray.push_back(safePageLen.ValueOrDie());
   }
 
   int nOffsetE = GetEndOfFirstPageOffset();
diff --git a/core/fpdfapi/fpdf_parser/cpdf_hint_tables.h b/core/fpdfapi/fpdf_parser/cpdf_hint_tables.h
index 35fbdcb79b..cda0925de8 100644
--- a/core/fpdfapi/fpdf_parser/cpdf_hint_tables.h
+++ b/core/fpdfapi/fpdf_parser/cpdf_hint_tables.h
@@ -20,7 +20,7 @@ class CPDF_Stream;
 class CPDF_HintTables {
  public:
   CPDF_HintTables(CPDF_DataAvail* pDataAvail, CPDF_Dictionary* pLinearized);
-  ~CPDF_HintTables();
+  virtual ~CPDF_HintTables();
 
   bool GetPagePos(int index,
                   FX_FILESIZE* szPageStartPos,
@@ -39,12 +39,13 @@ class CPDF_HintTables {
   uint32_t GetItemLength(int index, const std::vector<FX_FILESIZE>& szArray);
 
  private:
-  int GetEndOfFirstPageOffset() const;
-  int GetNumberOfPages() const;
-  int GetFirstPageObjectNumber() const;
-  int GetFirstPageNumber() const;
-  int ReadPrimaryHintStreamOffset() const;
-  int ReadPrimaryHintStreamLength() const;
+  // Tests can override.
+  virtual int GetEndOfFirstPageOffset() const;
+  virtual int GetNumberOfPages() const;
+  virtual int GetFirstPageObjectNumber() const;
+  virtual int GetFirstPageNumber() const;
+  virtual int ReadPrimaryHintStreamOffset() const;
+  virtual int ReadPrimaryHintStreamLength() const;
 
   // Helper for the ReadPrimaryHintStream methods above.
   int ReadPrimaryHintStream(int index) const;
-- 
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