Merge to M51: Fix integer issues leading to out of bounds access in fx_ge_text.cpp.

- Using |-skew| to get positive index, which doesn't work when skew is
  INT_MIN
- Incorrect logic when determining when to use |-skew| as an index.

TBR=tsepez@chromium.org
BUG=chromium:601362

Original Review URL: https://codereview.chromium.org/1875673004

(cherry picked from commit b8627c9d13884d48943d8a7a5381eaf0bb2c08d9)

Review URL: https://codereview.chromium.org/1898853002 .

5 files changed, 143 insertions, 8 deletions

diff --git a/BUILD.gn b/BUILD.gn
index 32d7886b98..b13a1bd360 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -1641,6 +1641,7 @@ test("pdfium_embeddertests") {
     "core/fpdfapi/fpdf_parser/fpdf_parser_decode_embeddertest.cpp",
     "core/fpdfapi/fpdf_render/fpdf_render_loadimage_embeddertest.cpp",
     "core/fpdfapi/fpdf_render/fpdf_render_pattern_embeddertest.cpp",
+    "core/fxge/ge/fx_ge_text_embeddertest.cpp",
     "fpdfsdk/fpdf_dataavail_embeddertest.cpp",
     "fpdfsdk/fpdfdoc_embeddertest.cpp",
     "fpdfsdk/fpdfedit_embeddertest.cpp",
diff --git a/core/fxge/ge/fx_ge_text.cpp b/core/fxge/ge/fx_ge_text.cpp
index 0815bfaa67..ce14631f5e 100644
--- a/core/fxge/ge/fx_ge_text.cpp
+++ b/core/fxge/ge/fx_ge_text.cpp
@@ -4,6 +4,8 @@
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
+#include <limits>
+
 #include "core/fxge/ge/fx_text_int.h"
 #include "core/include/fxcodec/fx_codec.h"
 #include "core/include/fxge/fx_freetype.h"
@@ -1566,10 +1568,14 @@ CFX_GlyphBitmap* CFX_FaceCache::RenderGlyph(CFX_Font* pFont,
       skew = pSubstFont->m_ItalicAngle;
     }
     if (skew) {
-      // skew is nonpositive so -skew is used as the index.
-      skew = -skew <= static_cast<int>(ANGLESKEW_ARRAY_SIZE)
-                 ? -58
-                 : -g_AngleSkew[-skew];
+      // |skew| is nonpositive so |-skew| is used as the index. We need to make
+      // sure |skew| != INT_MIN since -INT_MIN is undefined.
+      if (skew <= 0 && skew != std::numeric_limits<int>::min() &&
+          static_cast<size_t>(-skew) < ANGLESKEW_ARRAY_SIZE) {
+        skew = -g_AngleSkew[-skew];
+      } else {
+        skew = -58;
+      }
       if (pFont->IsVertical())
         ft_matrix.yx += ft_matrix.yy * skew / 100;
       else
@@ -1832,10 +1838,14 @@ CFX_PathData* CFX_Font::LoadGlyphPath(uint32_t glyph_index, int dest_width) {
   if (m_pSubstFont) {
     if (m_pSubstFont->m_ItalicAngle) {
       int skew = m_pSubstFont->m_ItalicAngle;
-      // skew is nonpositive so -skew is used as the index.
-      skew = -skew <= static_cast<int>(ANGLESKEW_ARRAY_SIZE)
-                 ? -58
-                 : -g_AngleSkew[-skew];
+      // |skew| is nonpositive so |-skew| is used as the index. We need to make
+      // sure |skew| != INT_MIN since -INT_MIN is undefined.
+      if (skew <= 0 && skew != std::numeric_limits<int>::min() &&
+          static_cast<size_t>(-skew) < ANGLESKEW_ARRAY_SIZE) {
+        skew = -g_AngleSkew[-skew];
+      } else {
+        skew = -58;
+      }
       if (m_bVertical)
         ft_matrix.yx += ft_matrix.yy * skew / 100;
       else
diff --git a/core/fxge/ge/fx_ge_text_embeddertest.cpp b/core/fxge/ge/fx_ge_text_embeddertest.cpp
new file mode 100644
index 0000000000..045b6dc869
--- /dev/null
+++ b/core/fxge/ge/fx_ge_text_embeddertest.cpp
@@ -0,0 +1,18 @@
+// Copyright 2016 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 FXGETextEmbedderTest : public EmbedderTest {};
+
+TEST_F(FXGETextEmbedderTest, BadItalic) {
+  // Shouldn't crash.
+  EXPECT_TRUE(OpenDocument("bug_601362.pdf"));
+  FPDF_PAGE page = LoadPage(0);
+  EXPECT_NE(nullptr, page);
+  FPDF_BITMAP bitmap = RenderPage(page);
+  FPDFBitmap_Destroy(bitmap);
+  UnloadPage(page);
+}
diff --git a/pdfium.gyp b/pdfium.gyp
index dd864e91da..b13fcef89a 100644
--- a/pdfium.gyp
+++ b/pdfium.gyp
@@ -974,6 +974,7 @@
         'core/fpdfapi/fpdf_parser/fpdf_parser_decode_embeddertest.cpp',
         'core/fpdfapi/fpdf_render/fpdf_render_loadimage_embeddertest.cpp',
         'core/fpdfapi/fpdf_render/fpdf_render_pattern_embeddertest.cpp',
+        'core/fxge/ge/fx_ge_text_embeddertest.cpp',
         'fpdfsdk/fpdf_dataavail_embeddertest.cpp',
         'fpdfsdk/fpdfdoc_embeddertest.cpp',
         'fpdfsdk/fpdfedit_embeddertest.cpp',
diff --git a/testing/resources/bug_601362.pdf b/testing/resources/bug_601362.pdf
new file mode 100644
index 0000000000..d21a83405e
--- /dev/null
+++ b/testing/resources/bug_601362.pdf
@@ -0,0 +1,105 @@
+%PDF-1.5
+%¿÷¢þ
+1 0 obj
+<< /Lang (en-US) /MarkInfo << /Marked true >> /Pages 3 0 R /Type /Catalog >>
+endobj
+2 0 obj
+<< /CreationDate (D:20160411190039+00'00') /Creator (Microsoft Word) /ModDate (D:20160411190039+00'00') >>
+endobj
+3 0 obj
+<< /Count 1 /Kids [ 4 0 R ] /Type /Pages >>
+endobj
+4 0 obj
+<< /Contents 5 0 R /Group << /CS /DeviceRGB /S /Transparency /Type /Group >> /MediaBox [ 0 0 612 792 ] /Parent 3 0 R /Resources << /ExtGState << /GS7 6 0 R /GS8 7 0 R >> /Font << /F1 8 0 R /F2 9 0 R >> /ProcSet [ /PDF /Text /ImageB /ImageC /ImageI ] >> /StructParents 0 /Tabs /S /Type /Page >>
+endobj
+5 0 obj
+<< /Length 464 >>
+stream
+ /P <</MCID 0>> BDC q
+0.00000912 0 612 792 re
+W* n
+BT
+/F1 11 Tf
+1 0 0 1 72.025 709.72 Tm
+/GS7 gs
+0 g
+/GS8 gs
+0 G
+[(T)10(est)] TJ
+ET
+Q
+q
+0.00000912 0 612 792 re
+W* n
+BT
+/F2 11 Tf
+1 0 0 1 90.8 709.72 Tm
+0 g
+0 G
+[( )] TJ
+ET
+Q
+q
+0.00000912 0 612 792 re
+W* n
+BT
+/F2 11 Tf
+1 0 0 1 93.3 709.72 Tm
+0 g
+0 G
+[(f)10(il)5(e.)] TJ
+ET
+Q
+q
+0.00000912 0 612 792 re
+W* n
+BT
+/F1 11 Tf
+1 0 0 1 109.8 709.72 Tm
+0 g
+0 G
+[( )] TJ
+ET
+Q
+ EMC endstream
+endobj
+6 0 obj
+<< /BM /Normal /Type /ExtGState /ca 1 >>
+endobj
+7 0 obj
+<< /BM /Normal /CA 1 /Type /ExtGState >>
+endobj
+8 0 obj
+<< /BaseFont /ABCDEE+Calibri /Encoding /WinAnsiEncoding /FirstChar 32 /FontDescriptor 10 0 R /LastChar 116 /Name /F1 /Subtype /TrueType /Type /Font /Widths 11 0 R >>
+endobj
+9 0 obj
+<< /BaseFont /ABCDEE+Calibri,Italic /Encoding /WinAnsiEncoding /FirstChar 32 /FontDescriptor 12 0 R /LastChar 108 /Name /F2 /Subtype /TrueType /Type /Font >>
+endobj
+10 0 obj
+<< /Ascent 750 /AvgWidth 521 /CapHeight 750 /Descent -250 /Flags 32 /FontBBox [ -503 -250 1240 750 ] /FontName /ABCDEE+Calibri /FontWeight 400 /ItalicAngle 0 /MaxWidth 1743 /StemV 52 /Type /FontDescriptor /XHeight 250 >>
+endobj
+11 0 obj
+[ 226 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 487 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 498 0 0 0 0 0 0 0 0 0 0 0 0 0 391 335 ]
+endobj
+12 0 obj
+<< /Ascent 750 /AvgWidth 521 /CapHeight 750 /Descent -250 /Flags 32 /FontBBox [ -725 -250 1260 750 ] /FontName /ABCDEE+Calibri,Italic /FontWeight 400 /ItalicAngle 2147483649 /MaxWidth 1984 /StemV 52 /Type /FontDescriptor /XHeight 250 >>
+endobj
+xref
+0 13
+0000000000 65535 f 
+0000000015 00000 n 
+0000000107 00000 n 
+0000000229 00000 n 
+0000000288 00000 n 
+0000000597 00000 n 
+0000001111 00000 n 
+0000001167 00000 n 
+0000001223 00000 n 
+0000001404 00000 n 
+0000001577 00000 n 
+0000001814 00000 n 
+0000002014 00000 n 
+trailer << /Info 2 0 R /Root 1 0 R /Size 13 /ID [<205a1ea7cf6e0a45ac68694d38f6b9f7><32b8937a599b7da08d5dc591fd416f1b>] >>
+startxref
+2267
+%%EOF