Make m_pShadingObj a CPDF_Stream instead of CPDF_Object.

This object is required to be a stream and was being converted as such. With
the new type checking this caused us to pass a nullptr where previously we'd
have, incorrectly, cast a CPDF_Dictionary to a CPDF_Stream.

This CL changes the m_pShadingObj to always be a CPDF_Stream. Then, we never
go down the bad code path because we check if m_pShadingObj is nullptr earlier
and bail out.

BUG=chromium:547706
R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/1426713002 .

9 files changed, 128 insertions, 15 deletions

diff --git a/BUILD.gn b/BUILD.gn
index a2ddbadd55..4d100d1bf6 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -778,6 +778,7 @@ test("pdfium_embeddertests") {
   sources = [
     "core/src/fpdfapi/fpdf_parser/fpdf_parser_decode_embeddertest.cpp",
     "core/src/fpdfapi/fpdf_parser/fpdf_parser_parser_embeddertest.cpp",
+    "core/src/fpdfapi/fpdf_render/fpdf_render_pattern_embeddertest.cpp",
     "fpdfsdk/src/fpdf_dataavail_embeddertest.cpp",
     "fpdfsdk/src/fpdfdoc_embeddertest.cpp",
     "fpdfsdk/src/fpdfformfill_embeddertest.cpp",
diff --git a/core/include/fpdfapi/fpdf_resource.h b/core/include/fpdfapi/fpdf_resource.h
index 9fe6e2b95f..0b85333cfc 100644
--- a/core/include/fpdfapi/fpdf_resource.h
+++ b/core/include/fpdfapi/fpdf_resource.h
@@ -688,7 +688,7 @@ class CPDF_ShadingPattern : public CPDF_Pattern {
 
   ~CPDF_ShadingPattern() override;
 
-  CPDF_Object* m_pShadingObj;
+  CPDF_Stream* m_pShadingObj;
 
   FX_BOOL m_bShadingObj;
 
diff --git a/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp b/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
index b12a65a844..bd4319df11 100644
--- a/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
+++ b/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
@@ -1128,10 +1128,9 @@ void CPDF_StreamContentParser::Handle_ShadeFill() {
     bbox = m_BBox;
   }
   if (pShading->m_ShadingType >= 4) {
-    bbox.Intersect(_GetShadingBBox(ToStream(pShading->m_pShadingObj),
-                                   pShading->m_ShadingType, &pObj->m_Matrix,
-                                   pShading->m_pFunctions, pShading->m_nFuncs,
-                                   pShading->m_pCS));
+    bbox.Intersect(_GetShadingBBox(
+        pShading->m_pShadingObj, pShading->m_ShadingType, &pObj->m_Matrix,
+        pShading->m_pFunctions, pShading->m_nFuncs, pShading->m_pCS));
   }
   pObj->m_Left = bbox.left;
   pObj->m_Right = bbox.right;
diff --git a/core/src/fpdfapi/fpdf_page/fpdf_page_pattern.cpp b/core/src/fpdfapi/fpdf_page/fpdf_page_pattern.cpp
index 7b04d8cd33..d06f481138 100644
--- a/core/src/fpdfapi/fpdf_page/fpdf_page_pattern.cpp
+++ b/core/src/fpdfapi/fpdf_page/fpdf_page_pattern.cpp
@@ -71,12 +71,12 @@ CPDF_ShadingPattern::CPDF_ShadingPattern(CPDF_Document* pDoc,
     CPDF_Dictionary* pDict = m_pPatternObj->GetDict();
     ASSERT(pDict != NULL);
     m_Pattern2Form = pDict->GetMatrix(FX_BSTRC("Matrix"));
-    m_pShadingObj = pDict->GetElementValue(FX_BSTRC("Shading"));
+    m_pShadingObj = ToStream(pDict->GetElementValue(FX_BSTRC("Shading")));
     if (parentMatrix) {
       m_Pattern2Form.Concat(*parentMatrix);
     }
   } else {
-    m_pShadingObj = pPatternObj;
+    m_pShadingObj = ToStream(pPatternObj);
   }
   m_ShadingType = 0;
   m_pCS = NULL;
diff --git a/core/src/fpdfapi/fpdf_render/fpdf_render_pattern.cpp b/core/src/fpdfapi/fpdf_render/fpdf_render_pattern.cpp
index 4ed6c07675..015f1a3166 100644
--- a/core/src/fpdfapi/fpdf_render/fpdf_render_pattern.cpp
+++ b/core/src/fpdfapi/fpdf_render/fpdf_render_pattern.cpp
@@ -881,20 +881,18 @@ void CPDF_RenderStatus::DrawShading(CPDF_ShadingPattern* pPattern,
                         pColorSpace, alpha);
       break;
     case 4: {
-      DrawFreeGouraudShading(pBitmap, &FinalMatrix,
-                             ToStream(pPattern->m_pShadingObj), pFuncs, nFuncs,
-                             pColorSpace, alpha);
+      DrawFreeGouraudShading(pBitmap, &FinalMatrix, pPattern->m_pShadingObj,
+                             pFuncs, nFuncs, pColorSpace, alpha);
     } break;
     case 5: {
-      DrawLatticeGouraudShading(pBitmap, &FinalMatrix,
-                                ToStream(pPattern->m_pShadingObj), pFuncs,
-                                nFuncs, pColorSpace, alpha);
+      DrawLatticeGouraudShading(pBitmap, &FinalMatrix, pPattern->m_pShadingObj,
+                                pFuncs, nFuncs, pColorSpace, alpha);
     } break;
     case 6:
     case 7: {
       DrawCoonPatchMeshes(pPattern->m_ShadingType - 6, pBitmap, &FinalMatrix,
-                          ToStream(pPattern->m_pShadingObj), pFuncs, nFuncs,
-                          pColorSpace, fill_mode, alpha);
+                          pPattern->m_pShadingObj, pFuncs, nFuncs, pColorSpace,
+                          fill_mode, alpha);
     } break;
   }
   if (bAlphaMode) {
diff --git a/core/src/fpdfapi/fpdf_render/fpdf_render_pattern_embeddertest.cpp b/core/src/fpdfapi/fpdf_render/fpdf_render_pattern_embeddertest.cpp
new file mode 100644
index 0000000000..30d7a416be
--- /dev/null
+++ b/core/src/fpdfapi/fpdf_render/fpdf_render_pattern_embeddertest.cpp
@@ -0,0 +1,16 @@
+// Copyright 2015 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.
+
+#include "../../../testing/embedder_test.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+class FPDFRenderPatternEmbeddertest : public EmbedderTest {};
+
+TEST_F(FPDFRenderPatternEmbeddertest, LoadError_547706) {
+  // Test shading where object is a dictionary instead of a stream.
+  EXPECT_TRUE(OpenDocument("testing/resources/bug_547706.pdf"));
+  FPDF_PAGE page = LoadPage(0);
+  RenderPage(page);
+  UnloadPage(page);
+}
diff --git a/pdfium.gyp b/pdfium.gyp
index 2aba2a7156..35e12e2dc3 100644
--- a/pdfium.gyp
+++ b/pdfium.gyp
@@ -749,6 +749,7 @@
       'sources': [
         'core/src/fpdfapi/fpdf_parser/fpdf_parser_decode_embeddertest.cpp',
         'core/src/fpdfapi/fpdf_parser/fpdf_parser_parser_embeddertest.cpp',
+        'core/src/fpdfapi/fpdf_render/fpdf_render_pattern_embeddertest.cpp',
         'fpdfsdk/src/fpdf_dataavail_embeddertest.cpp',
         'fpdfsdk/src/fpdfdoc_embeddertest.cpp',
         'fpdfsdk/src/fpdfformfill_embeddertest.cpp',
diff --git a/testing/resources/bug_547706.in b/testing/resources/bug_547706.in
new file mode 100644
index 0000000000..4c31f19211
--- /dev/null
+++ b/testing/resources/bug_547706.in
@@ -0,0 +1,43 @@
+{{header}}
+
+{{object 1 0}}
+<< /Pages 2 0 R >>
+endobj
+
+{{object 2 0}}
+<< /Kids [ 3 0 R ] >>
+endobj
+
+{{object 3 0}}
+<< /Contents 4 0 R /Resources << /Pattern 6 0 R >>>>
+endobj
+
+{{object 4 0}}
+<< /Length 5 0 R >>
+stream
+/R9 scn
+0 0 2479 3508 re
+/R11 36 Tf
+[(1)-12288.9(2)]TJ
+endstream
+endobj
+
+{{object 6 0}}
+<< /R9 7 0 R >>
+endobj
+
+{{object 7 0}}
+<< /PatternType 2 /Shading 8 0 R >>
+endobj
+
+{{object 8 0}}
+<< /BitsPerComponent 16 /ColorSpace /DeviceRGB /ShadingType 5 >>
+endobj
+
+{{xref}}
+trailer <<
+  /Root 1 0 R
+  /Size 9
+>>
+{{startxref}}
+%%EOF
diff --git a/testing/resources/bug_547706.pdf b/testing/resources/bug_547706.pdf
new file mode 100644
index 0000000000..8003b3c488
--- /dev/null
+++ b/testing/resources/bug_547706.pdf
@@ -0,0 +1,55 @@
+%PDF-1.7
+% ò¤ô
+
+1 0 obj
+<< /Pages 2 0 R >>
+endobj
+
+2 0 obj
+<< /Kids [ 3 0 R ] >>
+endobj
+
+3 0 obj
+<< /Contents 4 0 R /Resources << /Pattern 6 0 R >>>>
+endobj
+
+4 0 obj
+<< /Length 5 0 R >>
+stream
+/R9 scn
+0 0 2479 3508 re
+/R11 36 Tf
+[(1)-12288.9(2)]TJ
+endstream
+endobj
+
+6 0 obj
+<< /R9 7 0 R >>
+endobj
+
+7 0 obj
+<< /PatternType 2 /Shading 8 0 R >>
+endobj
+
+8 0 obj
+<< /BitsPerComponent 16 /ColorSpace /DeviceRGB /ShadingType 5 >>
+endobj
+
+xref
+0 9
+0000000000 65535 f 
+0000000016 00000 n 
+0000000051 00000 n 
+0000000089 00000 n 
+0000000158 00000 n 
+0000000000 65535 f 
+0000000266 00000 n 
+0000000298 00000 n 
+0000000350 00000 n 
+trailer <<
+  /Root 1 0 R
+  /Size 9
+>>
+startxref
+431
+%%EOF