Day 72 of #100DaysOfDeFI 🚀 Today I looked at arithmetic Over/Under Flows in #Solidity 👾 This vulnerability been secured by the current Solidity version 🦸♂️ Nevertheless, it is important to understand what it is and how to avoid it 👩🏻💻
#womenwhocode #100DaysOfCode
Summary 🧵
#womenwhocode #100DaysOfCode
Summary 🧵
1/ An overflow in Solidity occurs when a number is incremented beyond its maximum value. For example, if we have a uint8 with a value of 255 and increment it by 1, it will “reset” and set a value to 0. Remember, the maximum value for uint8 is 255❗
2/ Similar thing happens when we decrease a value beyond its minimal level. Taking the same example, if a uint8 is set to 0 and we decrease it by 1, it will set to 255, since 0 is the minimal value of uint8❗
3/ Let’s check it with code 👩🏻💻
4/ Deploy contract and check the value → it should be set to 0️⃣ Try to decrease a value and it will return 255 👇
5/ Increase it and it will be set back to 0 👇
6/ To avoid this vulnerability the best option is to use the latest version of Solidity 👾 There is also an option to use SafeMath library by OpenZeppelin that helps preventing overflows and underflows 👩🏻💻
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