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  • Smart Contract Vulnerabilities
    • Anchor
      • FV-ANC-1 Arithmetic Operations
        • FV-ANC-1-CL1 Overflow/underflow in arithmetic operations
        • FV-ANC-1-CL2 Division by zero
        • FV-ANC-1-CL3 Arbitrary rounding
      • FV-ANC-2 Signer Checks
        • FV-ANC-2-CL1 Unvalidated signers
        • FV-ANC-2-CL2 No is_signer check
      • FV-ANC-3 Account/Ownership Validations
        • FV-ANC-3-CL1 Trying to modify an account without checking if it's writeable
        • FV-ANC-3-CL2 Trying to access account data without ownership checks
        • FV-ANC-3-CL3 Usage of UncheckedAccount without manual ownership check
        • FV-ANC-3-CL4 Usage of UncheckedAccount without manual signer check
        • FV-ANC-3-CL5 No is_initialized check when operating on an account
        • FV-ANC-3-CL6 Missing account constraints
        • FV-ANC-3-CL7 Duplicate mutable accounts
        • FV-ANC-3-CL8 Using ctx.remaining_accounts without manual ownership check
        • FV-ANC-3-CL9 Using ctx.remaining_accounts without manual discriminator check
        • FV-ANC-3-CL10 Using ctx.remaining_accounts without non-zero data check
        • FV-ANC-3-CL11 No reload after account mutation
        • FV-ANC-3-CL12 Not validating a set address
      • FV-ANC-4 PDA Security
        • FV-ANC-4-CL1 Using create_program_address
      • FV-ANC-5 Cross-Program Invocation (CPI)
        • FV-ANC-5-CL1 Lack of validation of external program before CPI
        • FV-ANC-5-CL2 CPI without signer seeds
        • FV-ANC-5-CL3 Not unsetting signer status before a CPI
        • FV-ANC-5-CL4 Passing unnecessary accounts to CPIs
      • FV-ANC-6 Error Handling
        • FV-ANC-6-CL1 Unclear error messages
      • FV-ANC-7 Token Operations
        • FV-ANC-7-CL1 Unvalidated token mint & owner
        • FV-ANC-7-CL2 Using init with an ATA
      • FV-ANC-8 System Account Validation
        • FV-ANC-8-CL1 Unvalidated sysvar address
      • FV-ANC-9 Type Cosplay
        • FV-ANC-9-CL1 Not using discriminators to validate account types
        • FV-ANC-9-CL2 Account structures without discriminators
      • FV-ANC-10 Closing accounts
        • FV-ANC-10-CL1 Closing accounts without zeroing data & setting a closed discriminator
        • FV-ANC-10-CL2 Operations on accounts marked as closed
        • FV-ANC-10-CL3 Unintended closure by close constraint
    • Solidity
      • FV-SOL-1 Reentrancy
        • FV-SOL-1-C1 Single Function
        • FV-SOL-1-C2 Cross Function
        • FV-SOL-1-C3 Cross Contract
        • FV-SOL-1-C4 Cross Chain
        • FV-SOL-1-C5 Dynamic
        • FV-SOL-1-C6 Read-Only
      • FV-SOL-2 Precision Errors
        • FV-SOL-2-C1 Token Decimals
        • FV-SOL-2-C2 Floating Point
        • FV-SOL-2-C3 Rounding
        • FV-SOL-2-C4 Division by Zero
        • FV-SOL-2-C5 Time-Based
      • FV-SOL-3 Arithmetic Errors
        • FV-SOL-3-C1 Overflow and Underflow
        • FV-SOL-3-C2 Sign Extension
        • FV-SOL-3-C3 Truncation in Type Casting
        • FV-SOL-3-C4 Misuse of Environment Variables
      • FV-SOL-4 Bad Access Control
        • FV-SOL-4-C1 Using tx.origin for Authorization
        • FV-SOL-4-C2 Unrestricted Role Assignment
        • FV-SOL-4-C3 Lack of Multi-Signature for Crucial Operations
      • FV-SOL-5 Logic Errors
        • FV-SOL-5-C1 Boundary Misalignment
        • FV-SOL-5-C2 Incorrect Conditionals
        • FV-SOL-5-C3 Improper State Transitions
        • FV-SOL-5-C4 Misordered Calculations
        • FV-SOL-5-C5 Event Misreporting
      • FV-SOL-6 Unchecked Returns
        • FV-SOL-6-C1 Unchecked Call Return
        • FV-SOL-6-C2 Unchecked Transfer Return
        • FV-SOL-6-C3 Silent Fail
        • FV-SOL-6-C4 False Positive Success Assumption
        • FV-SOL-6-C5 Partial Execution with No Rollback
        • FV-SOL-6-C6 False Contract Existence Assumption
      • FV-SOL-7 Proxy Insecurities
        • FV-SOL-7-C1 delegatecall Storage Collision
        • FV-SOL-7-C2 Function Selector Collision
        • FV-SOL-7-C3 Centralized Update Control
        • FV-SOL-7-C4 Uninitialized Proxy
      • FV-SOL-8 Slippage
        • FV-SOL-8-C1 Price Manipulation
        • FV-SOL-8-C2 Front-Running
        • FV-SOL-8-C3 Insufficient Liquidity
        • FV-SOL-8-C4 Unexpected Gas Increase
      • FV-SOL-9 Unbounded Loops
        • FV-SOL-9-C1 Dynamic Array
        • FV-SOL-9-C2 Unrestricted Mapping
        • FV-SOL-9-C3 Recursive Calls
        • FV-SOL-9-C4 Reentrancy Loops
        • FV-SOL-9-C5 Nested Loops
      • FV-SOL-10 Oracle Manipulation
        • FV-SOL-10-C1 Incorrect Compounding Mechanism
        • FV-SOL-10-C2 Price Drift
        • FV-SOL-10-C3 Manipulation Through External Markets
        • FV-SOL-10-C4 Time Lags
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  1. Smart Contract Vulnerabilities
  2. Solidity
  3. FV-SOL-9 Unbounded Loops

FV-SOL-9-C2 Unrestricted Mapping

TLDR

Solidity mappings do not provide a way to iterate over keys natively. However, if developers use an array to track mapping keys for iteration, looping through the keys can lead to unbounded loops if the array grows indefinitely

Game

If this auxiliary array grows without restriction, what will looping over it do?

// SPDX-License-Identifier: MIT
// Open me in VSCode and really think before opening the hints!
// Add @audit tags wherever suspicious
// Go to the solidity docs to complete missing knowledge of what's happening here
// Solve by drafting a fix!
pragma solidity ^0.8.0;

contract UnrestrictedMappingGame {
    mapping(address => uint256) public balances;
    address[] public users;

    // Add or update a user's balance
    function setBalance(address user, uint256 amount) public {
        if (balances[user] == 0) {
            users.push(user);
        }
        balances[user] = amount;
    }

    // Sum up all balances
    function totalBalances() public view returns (uint256) {
        uint256 total = 0;
        for (uint256 i = 0; i < users.length; i++) {
            total += balances[users[i]];
        }
        return total;
    }
}

Consider how you can limit the size of the users array to ensure predictable gas consumption for functions like totalBalances.

Think about how precomputing or chunking operations might help avoid the need for full iteration in a single transaction.

contract UnrestrictedMappingGame {
    mapping(address => uint256) public balances;
    address[] public users;

    uint256 public maxUsers = 1000; // Fix: Restrict the maximum number of users

    function setBalance(address user, uint256 amount) public {
        if (balances[user] == 0) {
            require(users.length < maxUsers, "User limit reached"); // Fix: Enforce user limit
            users.push(user);
        }
        balances[user] = amount;
    }

    function totalBalances(uint256 start, uint256 end) public view returns (uint256) {
        require(end > start && end <= users.length, "Invalid range");
        uint256 total = 0;
        for (uint256 i = start; i < end; i++) {
            total += balances[users[i]];
        }
        return total;
    }
}
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Last updated 6 months ago

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