Clear decoders after the image decoder in the /Filter array.

During decoding, when an image decoder is encountered, any
subsequent decoders are ignored, but remain in the array. However,
later on CPDF_DIBSource::ValidateDictParam expects the image
decoder to be the last in the array, causing issues.

A check is also added in CPDF_DIBSource::GetScanline to ensure
that the calculated pitch value is <= the (4-aligned) pitch value in the
cached bitmap to prevent future issues.

Also cleans up some NULL usages.

BUG=552046
R=jun_fang@foxitsoftware.com, tsepez@chromium.org

Review URL: https://codereview.chromium.org/1406943005 .

1 files changed, 10 insertions, 0 deletions

diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_decode_embeddertest.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_decode_embeddertest.cpp
index 279151a87a..62da88b9ba 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_decode_embeddertest.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_decode_embeddertest.cpp
@@ -95,4 +95,14 @@ TEST_F(FPDFParserDecodeEmbeddertest, FlateDecode) {
   }
 }
 
+TEST_F(FPDFParserDecodeEmbeddertest, Bug_552046) {
+  // Tests specifying multiple image filters for a stream. Should not cause a
+  // crash when rendered.
+  EXPECT_TRUE(OpenDocument("bug_552046.pdf"));
+  FPDF_PAGE page = LoadPage(0);
+  FPDF_BITMAP bitmap = RenderPage(page);
+  FPDFBitmap_Destroy(bitmap);
+  UnloadPage(page);
+}
+
 #undef TEST_CASE