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fix(evm): consume all gas when a frame halts exceptionally #605

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fix(evm): consume all gas when a frame halts exceptionally #605

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17 changes: 17 additions & 0 deletions src/evm/evm.h
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Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,23 @@ constexpr auto MAX_SIZE_OF_INITCODE = 0xC000;
/// code.
static constexpr auto EMPTY_CODE_HASH =
0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470_bytes32;

/// Store the gas a finished frame hands back to its caller, applying the EVM's
/// terminal gas rule: an exceptional halt consumes all of the frame's gas, and
/// only a success or a revert returns any.
///
/// This must be the last write to `Result.gas_left`. The instance's own gas
/// counter is not authoritative once a frame has halted - the interpreter
/// zeroes the frame's gas rather than the instance's, and the JIT trap path
/// never touches either - so assigning `Instance::getGas()` unconditionally
/// hands the caller gas the EVM has already burned. evmone applies the same
/// rule in `make_execution_result`.
inline void setFrameGasLeft(evmc::Result &Result, uint64_t InstanceGas) {
const bool KeepsGas =
Result.status_code == EVMC_SUCCESS || Result.status_code == EVMC_REVERT;
Result.gas_left = KeepsGas ? static_cast<int64_t>(InstanceGas) : 0;
}

} // namespace zen::evm

#endif // ZEN_EVM_GAS_EVM_H
2 changes: 1 addition & 1 deletion src/runtime/runtime.cpp
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Expand Up @@ -785,7 +785,7 @@ void Runtime::callEVMMainOnPhysStack(EVMInstance &Inst, evmc_message &Msg,
} else {
callEVMInInterpMode(Inst, MsgWithCode, Result);
}
Result.gas_left = Inst.getGas();
zen::evm::setFrameGasLeft(Result, Inst.getGas());
}

void Runtime::callEVMMain(EVMInstance &Inst, evmc_message &Msg,
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5 changes: 3 additions & 2 deletions src/vm/dt_evmc_vm.cpp
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Expand Up @@ -6,6 +6,7 @@
#include "common/enums.h"
#include "common/errors.h"
#include "compiler/evm_frontend/evm_analyzer.h"
#include "evm/evm.h"
#include "evm/interpreter.h"
#include "evm/opcode_handlers.h"
#include "jit_profile.h"
Expand Down Expand Up @@ -691,7 +692,7 @@ evmc_result runInterpreterOnResolvedInstance(DTVM *VM, EVMModule *Mod,

evmc::Result Result =
std::move(const_cast<evmc::Result &>(Ctx.getExeResult()));
Result.gas_left = TheInst->getGas();
zen::evm::setFrameGasLeft(Result, TheInst->getGas());

return Result.release_raw();
}
Expand Down Expand Up @@ -985,7 +986,7 @@ evmc_result execute(evmc_vm *EVMInstance, const evmc_host_interface *Host,
VM->RT->callEVMInJITMode(*TheInst, MsgWithCode, Result);
#endif // ZEN_ENABLE_VIRTUAL_STACK

Result.gas_left = TheInst->getGas();
zen::evm::setFrameGasLeft(Result, TheInst->getGas());
return Result.release_raw();
}
#else
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