From e4ba1c02e80c402410344f1813e54946486c1c90 Mon Sep 17 00:00:00 2001
From: Bhargava Shastry <bhargava.shastry@ethereum.org>
Date: Fri, 1 Nov 2019 11:36:29 +0100
Subject: [PATCH] yul proto fuzzer: Catch exception early and propagate
 termination reason to harness

---
 test/tools/ossfuzz/strictasm_diff_ossfuzz.cpp | 38 ++++++-----------
 test/tools/ossfuzz/yulFuzzerCommon.cpp        | 23 +++++++++-
 test/tools/ossfuzz/yulFuzzerCommon.h          | 10 ++++-
 test/tools/ossfuzz/yulProto_diff_ossfuzz.cpp  | 42 ++++++-------------
 4 files changed, 55 insertions(+), 58 deletions(-)

diff --git a/test/tools/ossfuzz/strictasm_diff_ossfuzz.cpp b/test/tools/ossfuzz/strictasm_diff_ossfuzz.cpp
index c61bf9817..5b644812c 100644
--- a/test/tools/ossfuzz/strictasm_diff_ossfuzz.cpp
+++ b/test/tools/ossfuzz/strictasm_diff_ossfuzz.cpp
@@ -78,35 +78,21 @@ extern "C" int LLVMFuzzerTestOneInput(uint8_t const* _data, size_t _size)
 
 	ostringstream os1;
 	ostringstream os2;
-	try
-	{
-		yulFuzzerUtil::interpret(
-			os1,
-			stack.parserResult()->code,
-			EVMDialect::strictAssemblyForEVMObjects(langutil::EVMVersion())
-		);
-	}
-	catch (yul::test::StepLimitReached const&)
-	{
+	yulFuzzerUtil::TerminationReason termReason = yulFuzzerUtil::interpret(
+		os1,
+		stack.parserResult()->code,
+		EVMDialect::strictAssemblyForEVMObjects(langutil::EVMVersion())
+	);
+	if (termReason == yulFuzzerUtil::TerminationReason::StepLimitReached)
 		return 0;
-	}
-	catch (yul::test::InterpreterTerminatedGeneric const&)
-	{
-	}
 
 	stack.optimize();
-	try
-	{
-		yulFuzzerUtil::interpret(
-			os2,
-			stack.parserResult()->code,
-			EVMDialect::strictAssemblyForEVMObjects(langutil::EVMVersion()),
-			(yul::test::yul_fuzzer::yulFuzzerUtil::maxSteps * 1.5)
-		);
-	}
-	catch (yul::test::InterpreterTerminatedGeneric const&)
-	{
-	}
+	termReason = yulFuzzerUtil::interpret(
+		os2,
+		stack.parserResult()->code,
+		EVMDialect::strictAssemblyForEVMObjects(langutil::EVMVersion()),
+		(yul::test::yul_fuzzer::yulFuzzerUtil::maxSteps * 1.5)
+	);
 
 	bool isTraceEq = (os1.str() == os2.str());
 	yulAssert(isTraceEq, "Interpreted traces for optimized and unoptimized code differ.");
diff --git a/test/tools/ossfuzz/yulFuzzerCommon.cpp b/test/tools/ossfuzz/yulFuzzerCommon.cpp
index 36a2d9edc..2069582b0 100644
--- a/test/tools/ossfuzz/yulFuzzerCommon.cpp
+++ b/test/tools/ossfuzz/yulFuzzerCommon.cpp
@@ -20,7 +20,7 @@ using namespace std;
 using namespace yul;
 using namespace yul::test::yul_fuzzer;
 
-void yulFuzzerUtil::interpret(
+yulFuzzerUtil::TerminationReason yulFuzzerUtil::interpret(
 	ostream& _os,
 	shared_ptr<yul::Block> _ast,
 	Dialect const& _dialect,
@@ -44,6 +44,25 @@ void yulFuzzerUtil::interpret(
 		0x8e, 0xf3, 0x9b, 0xe4, 0x4f, 0x6c, 0x14, 0xde
 	};
 	Interpreter interpreter(state, _dialect);
-	interpreter(*_ast);
+
+	TerminationReason reason = TerminationReason::None;
+	try
+	{
+		interpreter(*_ast);
+	}
+	catch (StepLimitReached const&)
+	{
+		reason = TerminationReason::StepLimitReached;
+	}
+	catch (TraceLimitReached const&)
+	{
+		reason = TerminationReason::TraceLimitReached;
+	}
+	catch (ExplicitlyTerminated const&)
+	{
+		reason = TerminationReason::ExplicitlyTerminated;
+	}
+
 	state.dumpTraceAndState(_os);
+	return reason;
 }
diff --git a/test/tools/ossfuzz/yulFuzzerCommon.h b/test/tools/ossfuzz/yulFuzzerCommon.h
index fd48bb796..7cc0e156f 100644
--- a/test/tools/ossfuzz/yulFuzzerCommon.h
+++ b/test/tools/ossfuzz/yulFuzzerCommon.h
@@ -25,7 +25,15 @@ namespace yul_fuzzer
 {
 struct yulFuzzerUtil
 {
-	static void interpret(
+	enum class TerminationReason
+	{
+		ExplicitlyTerminated,
+		StepLimitReached,
+		TraceLimitReached,
+		None
+	};
+
+	static TerminationReason interpret(
 		std::ostream& _os,
 		std::shared_ptr<yul::Block> _ast,
 		Dialect const& _dialect,
diff --git a/test/tools/ossfuzz/yulProto_diff_ossfuzz.cpp b/test/tools/ossfuzz/yulProto_diff_ossfuzz.cpp
index 41cd6edab..c6ae3b368 100644
--- a/test/tools/ossfuzz/yulProto_diff_ossfuzz.cpp
+++ b/test/tools/ossfuzz/yulProto_diff_ossfuzz.cpp
@@ -66,9 +66,6 @@ DEFINE_PROTO_FUZZER(Program const& _input)
 		of.write(yul_source.data(), yul_source.size());
 	}
 
-	if (yul_source.size() > 1200)
-		return;
-
 	YulStringRepository::reset();
 
 	// AssemblyStack entry point
@@ -95,35 +92,22 @@ DEFINE_PROTO_FUZZER(Program const& _input)
 
 	ostringstream os1;
 	ostringstream os2;
-	try
-	{
-		yulFuzzerUtil::interpret(
-			os1,
-			stack.parserResult()->code,
-			EVMDialect::strictAssemblyForEVMObjects(langutil::EVMVersion())
-		);
-	}
-	catch (yul::test::StepLimitReached const&)
-	{
+	yulFuzzerUtil::TerminationReason termReason = yulFuzzerUtil::interpret(
+		os1,
+		stack.parserResult()->code,
+		EVMDialect::strictAssemblyForEVMObjects(langutil::EVMVersion())
+	);
+
+	if (termReason == yulFuzzerUtil::TerminationReason::StepLimitReached)
 		return;
-	}
-	catch (yul::test::InterpreterTerminatedGeneric const&)
-	{
-	}
 
 	stack.optimize();
-	try
-	{
-		yulFuzzerUtil::interpret(
-			os2,
-			stack.parserResult()->code,
-			EVMDialect::strictAssemblyForEVMObjects(langutil::EVMVersion()),
-			(yul::test::yul_fuzzer::yulFuzzerUtil::maxSteps * 1.5)
-		);
-	}
-	catch (yul::test::InterpreterTerminatedGeneric const&)
-	{
-	}
+	termReason = yulFuzzerUtil::interpret(
+		os2,
+		stack.parserResult()->code,
+		EVMDialect::strictAssemblyForEVMObjects(langutil::EVMVersion()),
+		(yul::test::yul_fuzzer::yulFuzzerUtil::maxSteps * 1.5)
+	);
 
 	bool isTraceEq = (os1.str() == os2.str());
 	yulAssert(isTraceEq, "Interpreted traces for optimized and unoptimized code differ.");