Filter false positives due to EVM errors.

Co-authored-by: Daniel Kirchner <daniel@ekpyron.org>

test/tools/ossfuzz/StackReuseCodegenFuzzer.cpp

@@ -49,6 +49,10 @@ static evmc::VM evmone = evmc::VM{evmc_create_evmone()};
 
 DEFINE_PROTO_FUZZER(Program const& _input)
 {
+	// Solidity creates an invalid instruction for subobjects, so we simply
+	// ignore them in this fuzzer.
+	if (_input.has_obj())
+		return;
 	bool filterStatefulInstructions = true;
 	bool filterUnboundedLoops = true;
 	ProtoConverter converter(
@@ -95,17 +99,26 @@ DEFINE_PROTO_FUZZER(Program const& _input)
 	// If the fuzzer synthesized input does not contain the revert opcode which
 	// we lazily check by string find, the EVM call should not revert.
 	bool noRevertInSource = yul_source.find("revert") == string::npos;
+	bool noInvalidInSource = yul_source.find("invalid") == string::npos;
+	if (noInvalidInSource)
+		solAssert(
+			callResult.status_code != EVMC_INVALID_INSTRUCTION,
+			"Invalid instruction."
+		);
 	if (noRevertInSource)
 		solAssert(
 			callResult.status_code != EVMC_REVERT,
 			"SolidityEvmoneInterface: EVM One reverted"
 		);
-	// Out of gas errors are problematic because it is possible that the
-	// optimizer makes them go away, making EVM state impossible to
-	// compare in general.
-	if (callResult.status_code == EVMC_OUT_OF_GAS)
+	// Bail out on serious errors encountered during a call.
+	if (YulEvmoneUtility{}.seriousCallError(callResult.status_code))
 		return;
-
+	solAssert(
+		(callResult.status_code == EVMC_SUCCESS ||
+		(!noRevertInSource && callResult.status_code == EVMC_REVERT) ||
+		(!noInvalidInSource && callResult.status_code == EVMC_INVALID_INSTRUCTION)),
+		"Unoptimised call failed."
+	);
 	ostringstream unoptimizedState;
 	unoptimizedState << hostContext.dumpState(deployResult.create_address);
 
@@ -135,10 +148,34 @@ DEFINE_PROTO_FUZZER(Program const& _input)
 			callResultOpt.status_code != EVMC_REVERT,
 			"SolidityEvmoneInterface: EVM One reverted"
 		);
+	if (noInvalidInSource)
+		solAssert(
+			callResultOpt.status_code != EVMC_INVALID_INSTRUCTION,
+			"Invalid instruction."
+		);
+	solAssert(
+		(callResultOpt.status_code == EVMC_SUCCESS ||
+		 (!noRevertInSource && callResultOpt.status_code == EVMC_REVERT) ||
+		 (!noInvalidInSource && callResultOpt.status_code == EVMC_INVALID_INSTRUCTION)),
+		"Optimised call failed."
+	);
 	ostringstream optimizedState;
 	optimizedState << hostContext.dumpState(deployResultOpt.create_address);
+
+	int64_t constexpr tolerance = 1000;
+	if (callResult.gas_left > callResultOpt.gas_left)
+		if (callResult.gas_left - callResultOpt.gas_left > tolerance)
+		{
+			cout << "Gas differential " << callResult.gas_left - callResultOpt.gas_left << endl;
+			cout << "Unoptimised bytecode" << endl;
+			cout << util::toHex(unoptimisedByteCode) << endl;
+			cout << "Optimised bytecode" << endl;
+			cout << util::toHex(optimisedByteCode) << endl;
+			solAssert(false, "Optimised code consumed more than +1000 gas.");
+		}
+
 	solAssert(
 		unoptimizedState.str() == optimizedState.str(),
-		"Storage of unoptimised and optimised stack reused code do not match."
+		"State of unoptimised and optimised stack reused code do not match."
 	);
 }

test/tools/ossfuzz/YulEvmoneInterface.cpp

@@ -78,3 +78,21 @@ evmc_message YulEvmoneUtility::callMessage(evmc_address _address)
 	call.kind = EVMC_CALL;
 	return call;
 }
+
+bool YulEvmoneUtility::seriousCallError(evmc_status_code _code)
+{
+	if (_code == EVMC_OUT_OF_GAS)
+		return true;
+	else if (_code == EVMC_STACK_OVERFLOW)
+		return true;
+	else if (_code == EVMC_STACK_UNDERFLOW)
+		return true;
+	else if (_code == EVMC_INTERNAL_ERROR)
+		return true;
+	else if (_code == EVMC_UNDEFINED_INSTRUCTION)
+		return true;
+	else if (_code == EVMC_INVALID_MEMORY_ACCESS)
+		return true;
+	else
+		return false;
+}

test/tools/ossfuzz/YulEvmoneInterface.h

@@ -54,5 +54,7 @@ struct YulEvmoneUtility
 	static evmc::result deployCode(solidity::bytes const& _input, EVMHost& _host);
 	/// @returns call message to be sent to @param _address.
 	static evmc_message callMessage(evmc_address _address);
+	/// @returns true if call result indicates a serious error, false otherwise.
+	static bool seriousCallError(evmc_status_code _code);
 };
 }