From d1d68505da0903592aad12e8711dd1bdcae388e9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pawe=C5=82=20Bylica?= <pawel.bylica@imapp.pl>
Date: Mon, 26 Jan 2015 11:00:31 +0100
Subject: [PATCH] Do not accept contract code with gas greater than 2^63. Keep
 gas counter in int64 type.

---
 libevmjit-cpp/JitVM.cpp      |  7 +++++--
 libevmjit/Arith256.cpp       |  1 -
 libevmjit/RuntimeData.h      |  2 +-
 libevmjit/RuntimeManager.cpp | 16 +++++++++-------
 4 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/libevmjit-cpp/JitVM.cpp b/libevmjit-cpp/JitVM.cpp
index 10133a0dc..c8ee74899 100644
--- a/libevmjit-cpp/JitVM.cpp
+++ b/libevmjit-cpp/JitVM.cpp
@@ -13,7 +13,9 @@ bytesConstRef JitVM::go(ExtVMFace& _ext, OnOpFunc const&, uint64_t)
 {
 	using namespace jit;
 
-	m_data.elems[RuntimeData::Gas]          = eth2llvm(m_gas);
+	if (m_gas > std::numeric_limits<decltype(m_data.gas)>::max())
+		BOOST_THROW_EXCEPTION(OutOfGas()); // Do not accept requests with gas > 2^63 (int64 max)
+
 	m_data.elems[RuntimeData::Address]      = eth2llvm(fromAddress(_ext.myAddress));
 	m_data.elems[RuntimeData::Caller]       = eth2llvm(fromAddress(_ext.caller));
 	m_data.elems[RuntimeData::Origin]       = eth2llvm(fromAddress(_ext.origin));
@@ -28,6 +30,7 @@ bytesConstRef JitVM::go(ExtVMFace& _ext, OnOpFunc const&, uint64_t)
 	m_data.code     = _ext.code.data();
 	m_data.codeSize = _ext.code.size();
 	m_data.callDataSize = _ext.data.size();
+	m_data.gas = static_cast<decltype(m_data.gas)>(m_gas);
 
 	auto env = reinterpret_cast<Env*>(&_ext);
 	auto exitCode = m_engine.run(_ext.code, &m_data, env);
@@ -49,7 +52,7 @@ bytesConstRef JitVM::go(ExtVMFace& _ext, OnOpFunc const&, uint64_t)
 		break;
 	}
 
-	m_gas = llvm2eth(m_data.elems[RuntimeData::Gas]);
+	m_gas = m_data.gas; // TODO: Remove m_gas field
 	return {std::get<0>(m_engine.returnData), std::get<1>(m_engine.returnData)};
 }
 
diff --git a/libevmjit/Arith256.cpp b/libevmjit/Arith256.cpp
index adb6cf9d5..14af9923c 100644
--- a/libevmjit/Arith256.cpp
+++ b/libevmjit/Arith256.cpp
@@ -65,7 +65,6 @@ llvm::Value* Arith256::mul(llvm::Value* _arg1, llvm::Value* _arg2)
 
 llvm::Value* Arith256::div(llvm::Value* _arg1, llvm::Value* _arg2)
 {
-
 	//return Endianness::toNative(m_builder, binaryOp(m_div, Endianness::toBE(m_builder, _arg1), Endianness::toBE(m_builder, _arg2)));
 	return binaryOp(m_div, _arg1, _arg2);
 }
diff --git a/libevmjit/RuntimeData.h b/libevmjit/RuntimeData.h
index 75d9c0267..3b128f317 100644
--- a/libevmjit/RuntimeData.h
+++ b/libevmjit/RuntimeData.h
@@ -14,7 +14,6 @@ struct RuntimeData
 {
 	enum Index
 	{
-		Gas,
 		Address,
 		Caller,
 		Origin,
@@ -37,6 +36,7 @@ struct RuntimeData
 	byte const* code = nullptr;
 	uint64_t codeSize = 0;
 	uint64_t callDataSize = 0;
+	int64_t gas = 0;
 };
 
 /// VM Environment (ExtVM) opaque type
diff --git a/libevmjit/RuntimeManager.cpp b/libevmjit/RuntimeManager.cpp
index ec4334390..75802593f 100644
--- a/libevmjit/RuntimeManager.cpp
+++ b/libevmjit/RuntimeManager.cpp
@@ -26,7 +26,8 @@ llvm::StructType* RuntimeManager::getRuntimeDataType()
 			Type::BytePtr,		// callData
 			Type::BytePtr,		// code
 			Type::Size,			// codeSize
-			Type::Size			// callDataSize
+			Type::Size,			// callDataSize
+			Type::Size,			// gas
 		};
 		type = llvm::StructType::create(elems, "RuntimeData");
 	}
@@ -58,7 +59,6 @@ llvm::Twine getName(RuntimeData::Index _index)
 	switch (_index)
 	{
 	default:						return "data";
-	case RuntimeData::Gas:			return "gas";
 	case RuntimeData::Address:		return "address";
 	case RuntimeData::Caller:		return "caller";
 	case RuntimeData::Origin:		return "origin";
@@ -150,7 +150,6 @@ llvm::Value* RuntimeManager::get(Instruction _inst)
 	switch (_inst)
 	{
 	default: assert(false); return nullptr;
-	case Instruction::GAS:			return get(RuntimeData::Gas);
 	case Instruction::ADDRESS:		return get(RuntimeData::Address);
 	case Instruction::CALLER:		return get(RuntimeData::Caller);
 	case Instruction::ORIGIN:		return get(RuntimeData::Origin);
@@ -200,14 +199,17 @@ llvm::Value* RuntimeManager::getJmpBuf()
 
 llvm::Value* RuntimeManager::getGas()
 {
-	return get(RuntimeData::Gas);
+	auto ptr = getBuilder().CreateStructGEP(getDataPtr(), 5);
+	auto value = getBuilder().CreateLoad(ptr, "gas");
+	assert(value->getType() == Type::Size);
+	return getBuilder().CreateZExt(value, Type::Word);
 }
 
 void RuntimeManager::setGas(llvm::Value* _gas)
 {
-	llvm::Value* idxList[] = {m_builder.getInt32(0), m_builder.getInt32(0), m_builder.getInt32(RuntimeData::Gas)};
-	auto ptr = m_builder.CreateInBoundsGEP(getDataPtr(), idxList, "gasPtr");
-	m_builder.CreateStore(_gas, ptr);
+	auto ptr = getBuilder().CreateStructGEP(getDataPtr(), 5);
+	auto newGas = getBuilder().CreateTrunc(_gas, Type::Size);
+	getBuilder().CreateStore(newGas, ptr);
 }
 
 }