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fix: never expand memory when access size is 0 #245

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Merged
zoowii merged 1 commit into from
Jan 8, 2026
Merged

fix: never expand memory when access size is 0 #245

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118 changes: 76 additions & 42 deletions src/compiler/evm_frontend/evm_imported.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -574,12 +574,15 @@ void evmSetMCopy(zen::runtime::EVMInstance *Instance, uint64_t Dest,
}
void evmSetReturn(zen::runtime::EVMInstance *Instance, uint64_t Offset,
uint64_t Len) {
if (!Instance->expandMemoryChecked(Offset, Len)) {
return;
std::vector<uint8_t> ReturnData;
if (Len > 0) {
if (!Instance->expandMemoryChecked(Offset, Len)) {
return;
}
auto &Memory = Instance->getMemory();
ReturnData = std::vector<uint8_t>(Memory.begin() + Offset,
Memory.begin() + Offset + Len);
}
auto &Memory = Instance->getMemory();
std::vector<uint8_t> ReturnData(Memory.begin() + Offset,
Memory.begin() + Offset + Len);
Instance->setReturnData(ReturnData);

evmc::Result ExeResult(EVMC_SUCCESS, 0,
Expand All @@ -591,6 +594,10 @@ void evmSetReturn(zen::runtime::EVMInstance *Instance, uint64_t Offset,
}
void evmSetCallDataCopy(zen::runtime::EVMInstance *Instance,
uint64_t DestOffset, uint64_t Offset, uint64_t Size) {
// When Size is 0, no memory operations are needed
if (Size == 0) {
return;
}
if (!Instance->expandMemoryChecked(DestOffset, Size)) {
return;
}
Expand Down Expand Up @@ -626,23 +633,27 @@ void evmSetCallDataCopy(zen::runtime::EVMInstance *Instance,
void evmSetExtCodeCopy(zen::runtime::EVMInstance *Instance,
const uint8_t *Address, uint64_t DestOffset,
uint64_t Offset, uint64_t Size) {
if (!Instance->expandMemoryChecked(DestOffset, Size)) {
return;
}
if (uint64_t CopyGas = calculateWordCopyGas(Size)) {
Instance->chargeGas(CopyGas);
}

const zen::runtime::EVMModule *Module = Instance->getModule();
ZEN_ASSERT(Module && Module->Host);
evmc::address Addr = loadAddressFromLE(Address);

evmc_revision Rev = Instance->getRevision();
if (Rev >= EVMC_BERLIN &&
Module->Host->access_account(Addr) == EVMC_ACCESS_COLD) {
Instance->chargeGas(zen::evm::ADDITIONAL_COLD_ACCOUNT_ACCESS_COST);
}

// When Size is 0, no memory operations are needed
if (Size == 0) {
return;
}

if (!Instance->expandMemoryChecked(DestOffset, Size)) {
return;
}
if (uint64_t CopyGas = calculateWordCopyGas(Size)) {
Instance->chargeGas(CopyGas);
}

auto &Memory = Instance->getMemory();
size_t CodeSize = Module->Host->get_code_size(Addr);

Expand All @@ -665,6 +676,10 @@ void evmSetExtCodeCopy(zen::runtime::EVMInstance *Instance,

void evmSetReturnDataCopy(zen::runtime::EVMInstance *Instance,
uint64_t DestOffset, uint64_t Offset, uint64_t Size) {
// When Size is 0, no memory operations are needed
if (Size == 0) {
return;
}
if (!Instance->expandMemoryChecked(DestOffset, Size)) {
return;
}
Expand Down Expand Up @@ -705,14 +720,16 @@ static void evmEmitLogGeneric(zen::runtime::EVMInstance *Instance,
const evmc_message *Msg = Instance->getCurrentMessage();
ZEN_ASSERT(Msg && "No current message set in EVMInstance");

// Calculate required memory size and charge gas
if (!Instance->expandMemoryChecked(Offset, Size)) {
return;
// Only expand memory if we actually need to access it (Size > 0)
const uint8_t *Data = nullptr;
if (Size > 0) {
if (!Instance->expandMemoryChecked(Offset, Size)) {
return;
}
auto &Memory = Instance->getMemory();
Data = Memory.data() + Offset;
}

auto &Memory = Instance->getMemory();
const uint8_t *Data = Memory.data() + Offset;

// Build topic array - only include non-null topics
evmc::bytes32 Topics[MaxTopics] = {};
size_t ActualNumTopics = 0;
Expand Down Expand Up @@ -805,13 +822,16 @@ const uint8_t *evmHandleCreateInternal(zen::runtime::EVMInstance *Instance,
}

// Calculate required memory size and charge gas
if (!Instance->expandMemoryChecked(Offset, Size)) {
Instance->setReturnData({});
return ZeroAddress;
}
const uint8_t *InitCode = nullptr;
if (Size > 0) {
if (!Instance->expandMemoryChecked(Offset, Size)) {
Instance->setReturnData({});
return ZeroAddress;
}

auto &Memory = Instance->getMemory();
const uint8_t *InitCode = Memory.data() + Offset;
auto &Memory = Instance->getMemory();
InitCode = Memory.data() + Offset;
}

// Create message for CREATE/CREATE2
evmc_message CreateMsg = {};
Expand Down Expand Up @@ -928,10 +948,15 @@ static uint64_t evmHandleCallInternal(zen::runtime::EVMInstance *Instance,
}

// Calculate required memory sizes for input and output
if (!Instance->expandMemoryChecked(ArgsOffset, ArgsSize, RetOffset,
RetSize)) {
Instance->setReturnData({});
return 0;
// Only expand memory if we actually need to access it
bool needArgsMemory = ArgsSize > 0;
bool needRetMemory = RetSize > 0;
if (needArgsMemory || needRetMemory) {
if (!Instance->expandMemoryChecked(ArgsOffset, ArgsSize, RetOffset,
RetSize)) {
Instance->setReturnData({});
return 0;
}
}

auto &Memory = Instance->getMemory();
Expand Down Expand Up @@ -1088,12 +1113,15 @@ uint64_t evmHandleStaticCall(zen::runtime::EVMInstance *Instance, uint64_t Gas,

void evmSetRevert(zen::runtime::EVMInstance *Instance, uint64_t Offset,
uint64_t Size) {
if (!Instance->expandMemoryChecked(Offset, Size)) {
return;
std::vector<uint8_t> ReturnData;
if (Size > 0) {
if (!Instance->expandMemoryChecked(Offset, Size)) {
return;
}
auto &Memory = Instance->getMemory();
ReturnData = std::vector<uint8_t>(Memory.begin() + Offset,
Memory.begin() + Offset + Size);
}
auto &Memory = Instance->getMemory();
std::vector<uint8_t> ReturnData(Memory.begin() + Offset,
Memory.begin() + Offset + Size);
Instance->setReturnData(std::move(ReturnData));
const int64_t GasLeft =
Instance ? static_cast<int64_t>(Instance->getGas()) : 0;
Expand All @@ -1107,6 +1135,10 @@ void evmSetRevert(zen::runtime::EVMInstance *Instance, uint64_t Offset,

void evmSetCodeCopy(zen::runtime::EVMInstance *Instance, uint64_t DestOffset,
uint64_t Offset, uint64_t Size) {
// When Size is 0, no memory operations are needed
if (Size == 0) {
return;
}
if (!Instance->expandMemoryChecked(DestOffset, Size)) {
return;
}
Expand Down Expand Up @@ -1136,15 +1168,17 @@ void evmSetCodeCopy(zen::runtime::EVMInstance *Instance, uint64_t DestOffset,

const uint8_t *evmGetKeccak256(zen::runtime::EVMInstance *Instance,
uint64_t Offset, uint64_t Length) {
if (!Instance->expandMemoryChecked(Offset, Length)) {
return nullptr;
const uint8_t *InputData = nullptr;
if (Length > 0) {
if (!Instance->expandMemoryChecked(Offset, Length)) {
return nullptr;
}
const uint64_t ExtraGas =
static_cast<uint64_t>(numWords(static_cast<uint64_t>(Length))) * 6;
Instance->chargeGas(ExtraGas);
auto &Memory = Instance->getMemory();
InputData = Memory.data() + Offset;
}
const uint64_t ExtraGas =
static_cast<uint64_t>(numWords(static_cast<uint64_t>(Length))) * 6;
Instance->chargeGas(ExtraGas);

auto &Memory = Instance->getMemory();
const uint8_t *InputData = Memory.data() + Offset;

auto &Cache = Instance->getMessageCache();
evmc::bytes32 HashResult;
Expand Down