Root + Impact

Description

• The buySnow() function allows users to purchase Snow tokens by specifying an amount parameter. However, the function does not validate that amount is greater than zero.

  If amount == 0:

  s_buyFee * amount evaluates to 0

  msg.value == 0 satisfies the condition

  _mint(msg.sender, 0) is executed

  The function proceeds successfully without reverting. While no funds are directly lost, the lack of input validation weakens protocol correctness and may introduce edge cases or inconsistencies in accounting and monitoring.

Risk

Likelihood:

This issue does not enable fund theft or protocol compromise but may lead to incorrect state updates, misleading events, and unexpected edge-case behavior.

Impact:

• Allowing zero-amount purchases may lead to unintended or misleading behavior

• Users can trigger the SnowBought event without paying any fee

• Off-chain systems (frontends, indexers, analytics) may interpret zero-value purchases as valid activity

• Protocol invariants or assumptions that a purchase always involves value transfer may be violated

• The function updates s_earnTimer even when no tokens are minted, potentially affecting reward timing logic.

Proof of Concept

Recommended Mitigation

Add explicit validation to ensure that the purchase amount is greater than zero: