Guard against self liquidations

contracts/red-bank/src/error.rs

@@ -81,6 +81,9 @@ pub enum ContractError {
     #[error("Amount to repay is greater than total debt")]
     CannotRepayMoreThanDebt {},
 
+    #[error("User cannot issue liquidation of own account")]
+    CannotLiquidateSelf {},
+
     #[error("User has a positive uncollateralized loan limit and thus cannot be liquidated")]
     CannotLiquidateWhenPositiveUncollateralizedLoanLimit {},
 

contracts/red-bank/src/execute.rs

@@ -701,6 +701,12 @@ pub fn liquidate(
     let recipient = User(&recipient_addr);
 
     // 1. Validate liquidation
+
+    // User cannot liquidate themselves
+    if info.sender == user_addr {
+        return Err(ContractError::CannotLiquidateSelf {});
+    }
+
     // If user (contract) has a positive uncollateralized limit then the user
     // cannot be liquidated
     if !user.uncollateralized_loan_limit(deps.storage, &debt_denom)?.is_zero() {

contracts/red-bank/tests/test_liquidate.rs

@@ -309,6 +309,24 @@ fn liquidate_if_no_coins_sent() {
     assert_eq!(error_res, PaymentError::NoFunds {}.into());
 }
 
+#[test]
+fn cannot_self_liquidate() {
+    let TestSuite {
+        mut deps,
+        ..
+    } = setup_test();
+
+    let env = mock_env(MockEnvParams::default());
+    let info = mock_info("liquidator", &[coin(100, "somecoin1")]);
+    let msg = ExecuteMsg::Liquidate {
+        user: "liquidator".to_string(),
+        collateral_denom: "collateral".to_string(),
+        recipient: None,
+    };
+    let error_res = execute(deps.as_mut(), env, info, msg).unwrap_err();
+    assert_eq!(error_res, ContractError::CannotLiquidateSelf {}.into());
+}
+
 #[test]
 fn liquidate_if_many_coins_sent() {
     let TestSuite {