Fix Jbig2 document context creation by checking proper pointer

The pointer a unique_ptr contains should be checked instead of the
pointer of the unique_ptr itself.

BUG=chromium:631912

Review-Url: https://codereview.chromium.org/2205573004

2 files changed, 20 insertions, 1 deletions

diff --git a/core/fxcodec/codec/fx_codec_embeddertest.cpp b/core/fxcodec/codec/fx_codec_embeddertest.cpp
new file mode 100644
index 0000000000..441494c0e6
--- /dev/null
+++ b/core/fxcodec/codec/fx_codec_embeddertest.cpp
@@ -0,0 +1,19 @@
+// 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 FXCodecEmbeddertest : public EmbedderTest {};
+
+TEST_F(FXCodecEmbeddertest, Bug_631912) {
+  // Test jbig2 image in PDF file can be loaded successfully.
+  // Should not crash.
+  EXPECT_TRUE(OpenDocument("bug_631912.pdf"));
+  FPDF_PAGE page = LoadPage(0);
+  EXPECT_NE(nullptr, page);
+  FPDF_BITMAP bitmap = RenderPage(page);
+  FPDFBitmap_Destroy(bitmap);
+  UnloadPage(page);
+}
diff --git a/core/fxcodec/codec/fx_codec_jbig.cpp b/core/fxcodec/codec/fx_codec_jbig.cpp
index adc57fd1ad..7713ca3ecb 100644
--- a/core/fxcodec/codec/fx_codec_jbig.cpp
+++ b/core/fxcodec/codec/fx_codec_jbig.cpp
@@ -20,7 +20,7 @@ JBig2_DocumentContext::~JBig2_DocumentContext() {}
 
 JBig2_DocumentContext* GetJBig2DocumentContext(
     std::unique_ptr<JBig2_DocumentContext>* pContextHolder) {
-  if (!pContextHolder)
+  if (!pContextHolder->get())
     pContextHolder->reset(new JBig2_DocumentContext());
   return pContextHolder->get();
 }