Identify and explain integer overflow and underflow risks in Solidity 0.8+ code.
npx skills add https://github.com/ccashwell/evm-cortex --skill integer-overflow
Please help me install this Agent Skill. Skill: integer-overflow Source: https://github.com/ccashwell/evm-cortex/tree/main/skills/integer-overflow Command: npx skills add https://github.com/ccashwell/evm-cortex --skill integer-overflow
This skill provides integer safety patterns for Solidity 0.8+ to prevent overflow and underflow by default, including guidance on unchecked blocks, safe casting, and handling phantom overflow.
Review a Solidity snippet and implement safe arithmetic patterns to eliminate overflow risks.
High-intent search queries and answers about installing and using this skill.
Solidity 0.8+ handles integer overflow and underflow automatically by reverting transactions when arithmetic bounds are exceeded. This built-in checking prevents common overflow errors without external libraries, ensuring safe math operations by default across contracts.
You should use unchecked blocks in Solidity when overflow is mathematically impossible, such as bounded loop increments. Unchecked blocks bypass automatic overflow checks to optimize gas performance where safe math outcomes are guaranteed by logic.
Phantom overflow in Solidity occurs when intermediate calculations exceed maximum limits despite the final result being valid. Mitigate phantom overflow by reordering arithmetic operations or applying safe casting patterns using libraries like SafeCast or FixedPointMathLib.
Perform safe casting in Solidity using libraries like SafeCast to prevent integer truncation and underflow during type conversions. Safe casting ensures downcasts revert on failure rather than silently truncating values, maintaining arithmetic integrity.
You do not need SafeMath libraries for standard overflow protection in Solidity 0.8+ because built-in automatic checks revert overflowing operations. SafeMath patterns are replaced by default checks, though libraries remain useful for phantom overflow and safe casting.
Best practices for handling integer edge cases in Solidity include relying on automatic 0.8+ checks, using unchecked blocks only when mathematically safe, and applying safe casting via libraries to prevent truncation and phantom overflow vulnerabilities.
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