Algo Ssstablecoinsss
AI First Flight #2
Beginner FriendlyDeFi
EXP
View results
Previous Next
Submission Details
Impact: low
Likelihood: low
Invalid

[M-04] Missing Zero Amount Check in _burn_dsc Allows No-Op Burns

rensley

Root + Impact

Description

  • The _burn_dsc() function does not validate that amount_dsc_to_burn is greater than zero.

  • While _mint_dsc and _deposit_collateral have this check, burning zero tokens is allowed.

  • This can be used to manipulate events or perform no-op operations that waste gas and pollute logs.

// Root cause in the codebase with @> marks to highlight the relevant section
​
@internal
def _burn_dsc(
amount_dsc_to_burn: uint256, on_behalf_of: address, dsc_from: address
):
@> # Missing: assert amount_dsc_to_burn > 0
self.user_to_dsc_minted[on_behalf_of] -= amount_dsc_to_burn
extcall DSC.burn_from(dsc_from, amount_dsc_to_burn)

Risk

Likelihood: Low

  • Reason 1 // Requires intentional zero-value calls

  • Reason 2 // No direct financial loss

Impact: Low

  • Impact 1 // Gas wastage on no-op operations

  • Impact 2 // Potential for event spam

  • Impact 3 // Inconsistent validation across functions

Proof of Concept

The following demonstrates that zero-amount burns are accepted, unlike zero-amount mints which correctly revert. This inconsistency could be exploited to spam events or waste gas.

def test_zero_burn_allowed():
with boa.env.prank(user):
# Zero mint correctly reverts
with boa.reverts("DSCEngine__NeedsMoreThanZero"):
dsce.mint_dsc(0)
# But zero burn is allowed (inconsistent)
dsc.approve(dsce, 0)
dsce.burn_dsc(0) # No revert - wastes gas

Recommended Mitigation

Add a zero-amount check to _burn_dsc for consistency with other functions. This prevents no-op operations and ensures all state-changing functions validate their inputs.

@internal
def _burn_dsc(
amount_dsc_to_burn: uint256, on_behalf_of: address, dsc_from: address
):
+ assert amount_dsc_to_burn > 0, "DSCEngine__NeedsMoreThanZero"
self.user_to_dsc_minted[on_behalf_of] -= amount_dsc_to_burn
extcall DSC.burn_from(dsc_from, amount_dsc_to_burn)
Updates

Lead Judging Commences

ai-first-flight-judge Lead Judge about 3 hours ago
Submission Judgement Published
Invalidated
Reason: Incorrect statement

Support

FAQs

Can't find an answer? Chat with us on Discord, Twitter or Linkedin.

Give us feedback!