Incrementing a fighter type generation will brick the element attribute selection forever because of a missing function to update `numElements`

[c4-bot-9]

Lines of code

https://github.com/code-423n4/2024-02-ai-arena/blob/main/src/FighterFarm.sol#L470

Vulnerability details

Impact

After incrementing the generation for a fighter type, all upcoming mints will only have the element corresponding to index 0.

Assesed as Medium since it breaks a chore mechanic, which can't be fixed or mitigated, since the contract will be bricked.

Vulnerability Details

When minting a new fighter, its corresponding element is calculated as:

uint256 element = dna % numElements[generation[fighterType]];

FighterFarm.sol#L470

The game will work fine for any fighterType on initialization, as numElements[0] = 3; is defined on the constructor.

The problem will arise when the generation is incremented with generation[fighterType] += 1;, which is an expected action at some point in time.

After that, numElements[generation[fighterType]] == numElements[1] == 0, as it is its default value. This will translate the element calculation to:

uint256 element = dna % 0; // @audit-info It will always be 0

The problem is that there isn't any function to update numElements.

So, the element for new minted fighters will always be zero, breaking a chore mechanic used to calculate strengths and weaknesses depending on pairing.

Recommended Mitigation Steps

Create a function to set the numElements for a specific generation.

Assessed type

DoS

[c4-pre-sort]

raymondfam marked the issue as sufficient quality report

[c4-pre-sort]

raymondfam marked the issue as duplicate of #45

[c4-judge]

HickupHH3 changed the severity to 3 (High Risk)

[c4-judge]

HickupHH3 marked the issue as partial-50