Gas Optimization: Tight variable packing in LPoolStorage.sol

[code423n4]

Handle

Dravee

Vulnerability details

Impact

Saving 2 slots (deployment cost)

Proof of Concept & Remediation

These variables should change be reordered:

File: LPoolInterface.sol
07:     //Guard variable for re-entrancy checks
08:     bool internal _notEntered;  //@audit-info 1 byte
09: 
10:     /**
11:      * EIP-20 token name for this token
12:      */
13:     string public name;  //@audit-info 32 bytes
14: 
15:     /**
16:      * EIP-20 token symbol for this token
17:      */
18:     string public symbol;//@audit-info 32 bytes
19: 
20:     /**
21:      * EIP-20 token decimals for this token
22:      */
23:     uint8 public decimals; //@audit-info 1 byte
24: 
25:     /**
26:     * Total number of tokens in circulation
27:     */
28:     uint public totalSupply;//@audit-info 32 bytes
29: 
30: 
31:     //Official record of token balances for each account
32:     mapping(address => uint) internal accountTokens;//@audit-info 32 bytes
33: 
34:     //Approved token transfer amounts on behalf of others
35:     mapping(address => mapping(address => uint)) internal transferAllowances;//@audit-info 32 bytes
36: 
37: 
38:     //Maximum borrow rate that can ever be applied (.0005% / block)
39:     uint internal constant borrowRateMaxMantissa = 0.0005e16;
40: 
41:     /**
42:     * Maximum fraction of borrower cap(80%)
43:     */
44:     uint public  borrowCapFactorMantissa;
45:     /**
46:      * Contract which oversees inter-lToken operations
47:      */
48:     address public controller; //@audit-info 20 bytes
49: 
50: 
51:     // Initial exchange rate used when minting the first lTokens (used when totalSupply = 0)
52:     uint internal initialExchangeRateMantissa;
53: 
54:     /**
55:      * Block number that interest was last accrued at
56:      */
57:     uint public accrualBlockNumber;
58: 
59:     /**
60:      * Accumulator of the total earned interest rate since the opening of the market
61:      */
62:     uint public borrowIndex;
63: 
64:     /**
65:      * Total amount of outstanding borrows of the underlying in this market
66:      */
67:     uint public totalBorrows;
68: 
69:     //useless
70:     uint internal totalCash;
71: 
72:     /**
73:     * @notice Fraction of interest currently set aside for reserves 20%
74:     */
75:     uint public reserveFactorMantissa;
76: 
77:     uint public totalReserves;
78: 
79:     address public underlying; //@audit-info 20 bytes
80: 
81:     bool public isWethPool; //@audit-info 1 byte

This way:

File: ControllerInterface.sol
61:     address public openLev; //@audit-info 20 bytes
62:
63:     bool public suspend; //@audit-info 1 byte
64:
65:     DexAggregatorInterface public dexAggregator; //@audit-info 32 bytes
66:
67:     OLETokenDistribution public oleTokenDistribution; //@audit-info 32 bytes

This would save 2 slots

[ColaM12]

Duplicate to #28

[0xleastwood]

I think this is valid. Keeping it open.