Gas Limit Vulnerabilities

Description

If a function requires more gas than the block gas limit to complete its execution, it will inevitably fail. These vulnerabilities typically occur in loops that iterate over dynamic data structures.

Impact

Functions vulnerable to gas limits can become uncallable, locking funds or freezing contract state.

Steps to Fix

1. Avoid loops that iterate over dynamic data structures. If possible, use mappings and keep track of keys separately.
2. Implement gas-efficient code and test functions with large inputs to ensure they won’t exceed the block gas limit.
3. Break down complex computations into multiple transactions if needed.

Example

A token smart contract that implements a function to transfer all tokens of an array of addresses could exceed the block gas limit if the array is too large.