M70: Validate decoder pipelines.
PDF decoders, AKA filters, can be chained together. There can be
an arbitrary number of decoding / decompressing filters in the pipeline,
but there should be at most 1 image decoder, and the image decoder
should only be at the end of the chain.
BUG=chromium:880675
TBR=tsepez@chromium.org
Change-Id: Iffa27c70ec1ed7574e38e0de23413840ee900959
Reviewed-on: https://pdfium-review.googlesource.com/42711
Reviewed-by: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
(cherry picked from commit 5f2ea0f6ef587f9f7a2fec9f80dbc82b94c97400)
Reviewed-on: https://pdfium-review.googlesource.com/42970
Reviewed-by: Lei Zhang <thestig@chromium.org>
diff --git a/core/fpdfapi/parser/fpdf_parser_decode.cpp b/core/fpdfapi/parser/fpdf_parser_decode.cpp
index de93acf..7a9f798 100644
--- a/core/fpdfapi/parser/fpdf_parser_decode.cpp
+++ b/core/fpdfapi/parser/fpdf_parser_decode.cpp
@@ -24,6 +24,7 @@
#include "core/fxcodec/fx_codec.h"
#include "core/fxcrt/fx_extension.h"
#include "third_party/base/numerics/safe_math.h"
+#include "third_party/base/stl_util.h"
namespace {
@@ -83,6 +84,22 @@
0x00f3, 0x00f4, 0x00f5, 0x00f6, 0x00f7, 0x00f8, 0x00f9, 0x00fa, 0x00fb,
0x00fc, 0x00fd, 0x00fe, 0x00ff};
+bool ValidateDecoderPipeline(const CPDF_Array* pDecoders) {
+ size_t count = pDecoders->GetCount();
+ if (count <= 1)
+ return true;
+
+ // TODO(thestig): Consolidate all the places that use these filter names.
+ static const char kValidDecoders[][16] = {
+ "FlateDecode", "Fl", "LZWDecode", "LZW", "ASCII85Decode", "A85",
+ "ASCIIHexDecode", "AHx", "RunLengthDecode", "RL"};
+ for (size_t i = 0; i < count - 1; ++i) {
+ if (!pdfium::ContainsValue(kValidDecoders, pDecoders->GetStringAt(i)))
+ return false;
+ }
+ return true;
+}
+
uint32_t A85Decode(pdfium::span<const uint8_t> src_span,
uint8_t** dest_buf,
uint32_t* dest_size) {
@@ -347,6 +364,9 @@
std::vector<std::pair<ByteString, const CPDF_Object*>> DecoderArray;
if (const CPDF_Array* pDecoders = pDecoder->AsArray()) {
+ if (!ValidateDecoderPipeline(pDecoders))
+ return false;
+
const CPDF_Array* pParamsArray = ToArray(pParams);
for (size_t i = 0; i < pDecoders->GetCount(); ++i) {
DecoderArray.push_back(
diff --git a/core/fpdfapi/parser/fpdf_parser_decode.h b/core/fpdfapi/parser/fpdf_parser_decode.h
index 1484dd7..8b06513 100644
--- a/core/fpdfapi/parser/fpdf_parser_decode.h
+++ b/core/fpdfapi/parser/fpdf_parser_decode.h
@@ -14,11 +14,14 @@
#include "third_party/base/span.h"
class CCodec_ScanlineDecoder;
+class CPDF_Array;
class CPDF_Dictionary;
// Indexed by 8-bit char code, contains unicode code points.
extern const uint16_t PDFDocEncoding[256];
+bool ValidateDecoderPipeline(const CPDF_Array* pDecoders);
+
ByteString PDF_EncodeString(const ByteString& src, bool bHex);
WideString PDF_DecodeText(const uint8_t* pData, uint32_t size);
WideString PDF_DecodeText(const ByteString& bstr);
diff --git a/core/fpdfapi/parser/fpdf_parser_decode_unittest.cpp b/core/fpdfapi/parser/fpdf_parser_decode_unittest.cpp
index aa37b79..4a6a286 100644
--- a/core/fpdfapi/parser/fpdf_parser_decode_unittest.cpp
+++ b/core/fpdfapi/parser/fpdf_parser_decode_unittest.cpp
@@ -4,9 +4,89 @@
#include "core/fpdfapi/parser/fpdf_parser_decode.h"
+#include "core/fpdfapi/parser/cpdf_array.h"
+#include "core/fpdfapi/parser/cpdf_name.h"
#include "testing/gtest/include/gtest/gtest.h"
#include "testing/test_support.h"
+TEST(fpdf_parser_decode, ValidateDecoderPipeline) {
+ {
+ // Empty decoder list is always valid.
+ CPDF_Array decoders;
+ EXPECT_TRUE(ValidateDecoderPipeline(&decoders));
+ }
+ {
+ // 1 decoder is always valid.
+ CPDF_Array decoders;
+ decoders.AddNew<CPDF_Name>("FlateEncode");
+ EXPECT_TRUE(ValidateDecoderPipeline(&decoders));
+ }
+ {
+ // 1 decoder is always valid, even with an unknown decoder.
+ CPDF_Array decoders;
+ decoders.AddNew<CPDF_Name>("FooBar");
+ EXPECT_TRUE(ValidateDecoderPipeline(&decoders));
+ }
+ {
+ // Valid 2 decoder pipeline.
+ CPDF_Array decoders;
+ decoders.AddNew<CPDF_Name>("AHx");
+ decoders.AddNew<CPDF_Name>("LZWDecode");
+ EXPECT_TRUE(ValidateDecoderPipeline(&decoders));
+ }
+ {
+ // Valid 2 decoder pipeline.
+ CPDF_Array decoders;
+ decoders.AddNew<CPDF_Name>("ASCII85Decode");
+ decoders.AddNew<CPDF_Name>("ASCII85Decode");
+ EXPECT_TRUE(ValidateDecoderPipeline(&decoders));
+ }
+ {
+ // Valid 5 decoder pipeline.
+ CPDF_Array decoders;
+ decoders.AddNew<CPDF_Name>("ASCII85Decode");
+ decoders.AddNew<CPDF_Name>("A85");
+ decoders.AddNew<CPDF_Name>("RunLengthDecode");
+ decoders.AddNew<CPDF_Name>("FlateDecode");
+ decoders.AddNew<CPDF_Name>("RL");
+ EXPECT_TRUE(ValidateDecoderPipeline(&decoders));
+ }
+ {
+ // Valid 5 decoder pipeline, with an image decoder at the end.
+ CPDF_Array decoders;
+ decoders.AddNew<CPDF_Name>("RunLengthDecode");
+ decoders.AddNew<CPDF_Name>("ASCII85Decode");
+ decoders.AddNew<CPDF_Name>("FlateDecode");
+ decoders.AddNew<CPDF_Name>("LZW");
+ decoders.AddNew<CPDF_Name>("DCTDecode");
+ EXPECT_TRUE(ValidateDecoderPipeline(&decoders));
+ }
+ {
+ // Invalid 2 decoder pipeline, with 2 image decoders.
+ CPDF_Array decoders;
+ decoders.AddNew<CPDF_Name>("DCTDecode");
+ decoders.AddNew<CPDF_Name>("CCITTFaxDecode");
+ EXPECT_FALSE(ValidateDecoderPipeline(&decoders));
+ }
+ {
+ // Invalid 2 decoder pipeline, with 1 image decoder at the start.
+ CPDF_Array decoders;
+ decoders.AddNew<CPDF_Name>("DCTDecode");
+ decoders.AddNew<CPDF_Name>("FlateDecode");
+ EXPECT_FALSE(ValidateDecoderPipeline(&decoders));
+ }
+ {
+ // Invalid 5 decoder pipeline.
+ CPDF_Array decoders;
+ decoders.AddNew<CPDF_Name>("FlateDecode");
+ decoders.AddNew<CPDF_Name>("FlateDecode");
+ decoders.AddNew<CPDF_Name>("DCTDecode");
+ decoders.AddNew<CPDF_Name>("FlateDecode");
+ decoders.AddNew<CPDF_Name>("FlateDecode");
+ EXPECT_FALSE(ValidateDecoderPipeline(&decoders));
+ }
+}
+
TEST(fpdf_parser_decode, A85Decode) {
pdfium::DecodeTestData test_data[] = {
// Empty src string.
