Bad indexing in CPDF_Document::FindPageIndex when page tree corrupt.

Moving to std::vector from the more forgiving CFX_ArrayTemplate
revealed the dubious page tree traversal, which depends on the
correctness of the /Count entries to properly summarize the total
descendants under a given node.

The only "correct" thing to do is to throw away these counts as parsed,
and re-compute them, perhaps in CountPages().  But I'm not willing to do
that since it may break unknown documents in the wild.

Pass out-params as pointers while we're at it.

BUG=680376

Review-Url: https://codereview.chromium.org/2636403003

5 files changed, 319 insertions, 19 deletions

diff --git a/core/fpdfapi/parser/cpdf_document.cpp b/core/fpdfapi/parser/cpdf_document.cpp
index 9e60aaa882..e425cfc328 100644
--- a/core/fpdfapi/parser/cpdf_document.cpp
+++ b/core/fpdfapi/parser/cpdf_document.cpp
@@ -516,18 +516,18 @@ void CPDF_Document::SetPageObjNum(int iPage, uint32_t objNum) {
 }
 
 int CPDF_Document::FindPageIndex(CPDF_Dictionary* pNode,
-                                 uint32_t& skip_count,
+                                 uint32_t* skip_count,
                                  uint32_t objnum,
-                                 int& index,
+                                 int* index,
                                  int level) {
   if (!pNode->KeyExist("Kids")) {
     if (objnum == pNode->GetObjNum())
-      return index;
+      return *index;
 
-    if (skip_count)
-      skip_count--;
+    if (*skip_count)
+      (*skip_count)--;
 
-    index++;
+    (*index)++;
     return -1;
   }
 
@@ -539,20 +539,17 @@ int CPDF_Document::FindPageIndex(CPDF_Dictionary* pNode,
     return -1;
 
   size_t count = pNode->GetIntegerFor("Count");
-  if (count <= skip_count) {
-    skip_count -= count;
-    index += count;
+  if (count <= *skip_count) {
+    (*skip_count) -= count;
+    (*index) += count;
     return -1;
   }
 
   if (count && count == pKidList->GetCount()) {
     for (size_t i = 0; i < count; i++) {
-      if (CPDF_Reference* pKid = ToReference(pKidList->GetObjectAt(i))) {
-        if (pKid->GetRefObjNum() == objnum) {
-          m_PageList[index + i] = objnum;
-          return static_cast<int>(index + i);
-        }
-      }
+      CPDF_Reference* pKid = ToReference(pKidList->GetObjectAt(i));
+      if (pKid && pKid->GetRefObjNum() == objnum)
+        return static_cast<int>(*index + i);
     }
   }
 
@@ -585,8 +582,15 @@ int CPDF_Document::GetPageIndex(uint32_t objnum) {
   if (!pPages)
     return -1;
 
-  int index = 0;
-  return FindPageIndex(pPages, skip_count, objnum, index);
+  int start_index = 0;
+  int found_index = FindPageIndex(pPages, &skip_count, objnum, &start_index);
+
+  // Corrupt page tree may yield out-of-range results.
+  if (found_index < 0 || found_index >= pdfium::CollectionSize<int>(m_PageList))
+    return -1;
+
+  m_PageList[found_index] = objnum;
+  return found_index;
 }
 
 int CPDF_Document::GetPageCount() const {
diff --git a/core/fpdfapi/parser/cpdf_document.h b/core/fpdfapi/parser/cpdf_document.h
index 65455480a4..3848ad6220 100644
--- a/core/fpdfapi/parser/cpdf_document.h
+++ b/core/fpdfapi/parser/cpdf_document.h
@@ -106,9 +106,9 @@ class CPDF_Document : public CPDF_IndirectObjectHolder {
   // When this method is called, m_pTreeTraversal[level] exists.
   CPDF_Dictionary* TraversePDFPages(int iPage, int* nPagesToGo, size_t level);
   int FindPageIndex(CPDF_Dictionary* pNode,
-                    uint32_t& skip_count,
+                    uint32_t* skip_count,
                     uint32_t objnum,
-                    int& index,
+                    int* index,
                     int level = 0);
   std::unique_ptr<CPDF_Object> ParseIndirectObject(uint32_t objnum) override;
   void LoadDocInternal();
diff --git a/fpdfsdk/fpdfdoc_embeddertest.cpp b/fpdfsdk/fpdfdoc_embeddertest.cpp
index 5441bb3ecf..3666687d4d 100644
--- a/fpdfsdk/fpdfdoc_embeddertest.cpp
+++ b/fpdfsdk/fpdfdoc_embeddertest.cpp
@@ -68,6 +68,16 @@ TEST_F(FPDFDocEmbeddertest, DestGetLocationInPage) {
   EXPECT_EQ(1, zoom);
 }
 
+TEST_F(FPDFDocEmbeddertest, BUG_680376) {
+  EXPECT_TRUE(OpenDocument("bug_680376.pdf"));
+
+  // Page number directly in item from Dests NameTree.
+  FPDF_DEST dest = FPDF_GetNamedDestByName(document(), "First");
+  EXPECT_TRUE(dest);
+  EXPECT_EQ(static_cast<unsigned long>(-1),
+            FPDFDest_GetPageIndex(document(), dest));
+}
+
 TEST_F(FPDFDocEmbeddertest, ActionGetFilePath) {
   EXPECT_TRUE(OpenDocument("launch_action.pdf"));
 
diff --git a/testing/resources/bug_680376.in b/testing/resources/bug_680376.in
new file mode 100644
index 0000000000..c21df245fb
--- /dev/null
+++ b/testing/resources/bug_680376.in
@@ -0,0 +1,130 @@
+{{header}}
+{{object 1 0}} <<
+  /Type /Catalog
+  /Pages 2 0 R
+  /Names <<
+    /Dests 10 0 R
+  >>
+  /Dests 14 0 R
+>>
+endobj
+{{object 2 0}} <<
+  /Type /Pages
+  /Count 4
+  /Kids [
+    5 0 R
+    6 0 R
+  ]
+>>
+endobj
+% Page number 0.
+{{object 3 0}} <<
+  /Type /Page
+  /Parent 2 0 R
+  /Resources <<
+    /Font <</F1 15 0 R>>
+  >>
+  /Contents [21 0 R]
+  /MediaBox [0 0 612 792]
+>>
+endobj
+% Page number 1.
+{{object 4 0}} <<
+  /Type /Page
+  /Parent 2 0 R
+  /Resources  <<
+    /Font <</F1 15 0 R>>
+  >>
+  /Contents [22 0 R]
+  /MediaBox [0 0 612 792]
+>>
+endobj
+% Tree node with bad Count, duplicated kids.
+{{object 5 0}} <<
+  /Type /Pages
+  /Parent 2 0 R
+  /Count 2
+  /Kids [
+    3 0 R
+    3 0 R
+    3 0 R
+    3 0 R
+  ]
+>>
+endobj
+% tree node with actual kids
+{{object 6 0}} <<
+  /Type /Pages
+  /Count 2
+  /Kids [
+    3 0 R
+    4 0 R
+  ]
+>>
+% Root of Dests NameTree
+{{object 10 0}} <<
+  /Kids [
+    11 0 R
+    12 0 R
+  ]
+>>
+endobj
+% Left child for Dests NameTree
+{{object 11 0}} <<
+  /Names [
+    (First) [4 0 R]
+  ]
+>>
+endobj
+% Right child for Dests NameTree
+{{object 12 0}} <<
+  /Names [
+    (WrongKey)  <</Fail [10 /FitH]>>
+    (WrongType) /NameNotAllowedHere
+  ]
+>>
+endobj
+% Old-style top-level Dests dictionary. Note that FirstAlternate
+% intentionally references non-exisstant page 11 and LastAlternate
+% intentionally references non-existant object 999.
+{{object 14 0}} <<
+  /FirstAlternate [11 /XYZ 200 400 800]
+  /LastAlternate  <</D [999 0 R /XYZ 0 0 -200]>>
+>>
+endobj
+% Font resource.
+{{object 15 0}} <<
+  /Type /Font
+  /Subtype /Type1
+  /BaseFont /Arial
+>>
+endobj
+% Content for page 0.
+{{object 21 0}} <<
+  /Length 0
+>>
+stream
+BT
+/F1 20 Tf
+100 600 TD (Page1)Tj
+ET
+endstream
+endobj
+% Content for page 1.
+{{object 22 0}} <<
+  /Length 0
+>>
+stream
+BT
+/F1 20 Tf
+100 600 TD (Page2)Tj
+ET
+endstream
+endobj
+{{xref}}
+trailer <<
+  /Size 6
+  /Root 1 0 R
+>>
+{{startxref}}
+%%EOF
diff --git a/testing/resources/bug_680376.pdf b/testing/resources/bug_680376.pdf
new file mode 100644
index 0000000000..fb01c57613
--- /dev/null
+++ b/testing/resources/bug_680376.pdf
@@ -0,0 +1,156 @@
+%PDF-1.7
+% ò¤ô
+1 0 obj <<
+  /Type /Catalog
+  /Pages 2 0 R
+  /Names <<
+    /Dests 10 0 R
+  >>
+  /Dests 14 0 R
+>>
+endobj
+2 0 obj <<
+  /Type /Pages
+  /Count 4
+  /Kids [
+    5 0 R
+    6 0 R
+  ]
+>>
+endobj
+% Page number 0.
+3 0 obj <<
+  /Type /Page
+  /Parent 2 0 R
+  /Resources <<
+    /Font <</F1 15 0 R>>
+  >>
+  /Contents [21 0 R]
+  /MediaBox [0 0 612 792]
+>>
+endobj
+% Page number 1.
+4 0 obj <<
+  /Type /Page
+  /Parent 2 0 R
+  /Resources  <<
+    /Font <</F1 15 0 R>>
+  >>
+  /Contents [22 0 R]
+  /MediaBox [0 0 612 792]
+>>
+endobj
+% Tree node with bad Count, duplicated kids.
+5 0 obj <<
+  /Type /Pages
+  /Parent 2 0 R
+  /Count 2
+  /Kids [
+    3 0 R
+    3 0 R
+    3 0 R
+    3 0 R
+  ]
+>>
+endobj
+% tree node with actual kids
+6 0 obj <<
+  /Type /Pages
+  /Count 2
+  /Kids [
+    3 0 R
+    4 0 R
+  ]
+>>
+% Root of Dests NameTree
+10 0 obj <<
+  /Kids [
+    11 0 R
+    12 0 R
+  ]
+>>
+endobj
+% Left child for Dests NameTree
+11 0 obj <<
+  /Names [
+    (First) [4 0 R]
+  ]
+>>
+endobj
+% Right child for Dests NameTree
+12 0 obj <<
+  /Names [
+    (WrongKey)  <</Fail [10 /FitH]>>
+    (WrongType) /NameNotAllowedHere
+  ]
+>>
+endobj
+% Old-style top-level Dests dictionary. Note that FirstAlternate
+% intentionally references non-exisstant page 11 and LastAlternate
+% intentionally references non-existant object 999.
+14 0 obj <<
+  /FirstAlternate [11 /XYZ 200 400 800]
+  /LastAlternate  <</D [999 0 R /XYZ 0 0 -200]>>
+>>
+endobj
+% Font resource.
+15 0 obj <<
+  /Type /Font
+  /Subtype /Type1
+  /BaseFont /Arial
+>>
+endobj
+% Content for page 0.
+21 0 obj <<
+  /Length 0
+>>
+stream
+BT
+/F1 20 Tf
+100 600 TD (Page1)Tj
+ET
+endstream
+endobj
+% Content for page 1.
+22 0 obj <<
+  /Length 0
+>>
+stream
+BT
+/F1 20 Tf
+100 600 TD (Page2)Tj
+ET
+endstream
+endobj
+xref
+0 23
+0000000000 65535 f 
+0000000015 00000 n 
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+0000001510 00000 n 
+0000001620 00000 n 
+trailer <<
+  /Size 6
+  /Root 1 0 R
+>>
+startxref
+1708
+%%EOF