GasChecker: Scalable Analysis for Discovering Gas-Inefficient Smart Contracts

Abstract

Ethereum, the largest blockchain for running smart contracts, charges the people who send transactions to deploy or invoke smart contracts for thwarting resource abuse. The amount of transaction fee depends on the size of that contract and the operations executed by that contract. Consequently, smart contracts with inefficient code will waste money. In this paper, we propose and develop the first tool, named GasChecker, for automatically identifying gas-inefficient code in smart contracts, and conduct the first empirical study on the prevalence of gas-inefficient code in the deployed smart contracts. More precisely, we first summarize ten gas-inefficient programming patterns and propose a new approach based on symbolic execution (SE) to detect them in the bytecode of smart contracts. To make our approach scalable to analyze millions of smart contracts, we parallelize SE by tailoring it to the MapReduce programming model, and propose a new feedback-based load balancing strategy to effectively utilize cloud resources. Extensive experiments show that GasChecker scales well with the increase of workers. The empirical study demonstrates that lots of real smart contracts contain various inefficient code. Manual investigation demonstrates that only 2.5% of discovered gas-inefficient instances are false positives.

Challenges and Common Solutions in Smart Contract Development

“…Accordingly, the transaction is reverted, and the address kept in the balanceList array will receive payments leading to denial of service [14], [20], [115]. Challenges related to resource management apply to Ethereum-based and EOSIO-based blockchains [14], [44], [116], [117]. In Ethereum, unlike Solidity, Vyper defines an upper bound on gas consumption per function call to prevent DoS from operations on unbounded data structures [115].…”

A comprehensive survey on smart contract construction and execution: paradigms, tools, and systems

“…Finally, by recalculation and verification of the optimized codes, GasReducer ensures that the outcome contract still works as expected. GasChecker 110 is another branch from Gasper . GasChecker enriches the gas-wasting patterns from seven to ten and can detect all these patterns through a parallel version of symbolic execution upon EVM bytecode, which greatly improves the performance when the workforce increases.…”

Static Profiling and Optimization of Ethereum Smart Contracts Using Resource Analysis

“…The number of smart contracts deployed in Ethereum blockchain is growing exponentially in the last few years. As a consequence, several tools [12]- [14], [19]- [21], [24]- [27], [29], [30], [34] have been developed to analyze and verify smart contracts both at Solidity and EVM level. Some of these approaches [20], [21], [24]- [26], [30], [34] are dynamic and try to identify potential vulnerabilities such as unhandled exceptions, transaction state dependencies, integer over-and under-flows or reentrancy vulnerabilities inspecting concrete execution traces using SMT solvers.…”

“…In the recent years, some tools [12]- [14], [29] focused on optimization of smart contracts have been published. In [13], the authors present the tool GASPER.…”

“…It identifies 7 gas costly patterns and advises the users that the analyzed Solidity code can be optimized. This work has been extended in two different tools: the tool GasReducer [14] increases the number of identified patterns to 24, and replaces the patterns by predefined EVM sequences that consume less gas than the original ones; the tool GasChecker [12] improves the performance of GASPER proposing a new approach based on a parallelized symbolic execution and cloud computing. Nevertheless, these tools are not fully automatic: the patterns need to be identified manually and they are not open-source or they are not publicly available, so we cannot compare our approach to theirs.…”