Beanstalk: The Finale

Summary

The protocol documentation provided contains information on the 144 possible cases for the current state of the protocol and the actions to be taken in each specific case.
However, there are inconsistencies between the data provided and the code implementation of the different cases.

Vulnerability Details

The contracts/libraries/LibCases.sol file handles the cases for beanstalk, to determine the change in temperature and Bean to maxLP gaugePoint per BDV ratio.

The parameters that are taken into account to calculate the different cases are:

• the Liquidity to Supply Ratio (L2SR) level (extremely low, reasonably low, reasonably high, extremely high)

• the debt level or Pod Rate level (excessively low, reasonably low, reasonably high, excessively high)

• the peg state (P < 1, P > 1, P > Q)

• the soil demand behavior (decreasing, steady, increasing).

The LibCases::setCasesV2 function sets the s.sys.casesV2 system variable that Stores the 144 cases resulting from the combination of the above parameters.

Given the structure of the elements contained in s.sys.casesV2, it is possible to see that the order of the cases is as indicated in the following table:

Table 1. Description of the 144 possible cases for the Beanstalk status, including their Id number and the corresponding line number in the LibCases::setCasesV2 function.

By comparing the cases description given in the Table 1 with the elements of s.sys.casesV2, it can be observed that there are some cases that are inconsistent with the description given in the documentation, specifically in the Maximum Temperature Flow Chart.

For example, the description for the case with Id = 1 is:

| 1 | "Extremely Low L2SR + Excessively Low Debt + P < 1 + Soil demand Steady" | 120 |

the corresponding number line in the LibCases::setCasesV2 function code is 120:

T_PLUS_3_L_MINUS_FIFTY

meaning that, for this case, the maximum temperature is increased by 3% and the Bean to Max LP Seed Ratio is decreased by 50%. Adjustment for the Bean to Max LP Seed Ratio is correct, however, the adjustment for the maximum temperature does not match the one indicated in the Maximum Temperature Flow Chart where, for this case, it is a 1% increasing instead of 3%.

Cases that do not match the description given in the documentation are those where the Bean price is less than 1, the pod rate is less than 15% (low debt) and the soil demand is steady. The cases ids are 1, 10, 37, 46, 73, 82, 109 and 118.

Impact

Impact: Medium

Likelihood: Low

Tools Used

Manual Review

Recommended Mitigation

It is recommended to update the cases contained in s.sys.casesV2 to match the desired behavior of the protocol given a specific case. The following code block fixes the mismatched cases.