perf(x/auth): only check memo when memo is present (#13528)

CHANGELOG.md

@@ -82,6 +82,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * [#13178](https://github.com/cosmos/cosmos-sdk/pull/13178) Add `cosmos.msg.v1.service` protobuf annotation to allow tooling to distinguish between Msg and Query services via reflection. 
 * [#13236](https://github.com/cosmos/cosmos-sdk/pull/13236) Integrate Filter Logging
 * [#13433](https://github.com/cosmos/cosmos-sdk/pull/13433) Remove dead code in cacheMergeIterator `Domain()`.
+* [#13528](https://github.com/cosmos/cosmos-sdk/pull/13528) Update `ValidateMemoDecorator` to only check memo against `MaxMemoCharacters` param when a memo is present.
 
 ### State Machine Breaking
 

baseapp/block_gas_test.go

@@ -166,7 +166,7 @@ func TestBaseApp_BlockGas(t *testing.T) {
 				require.Equal(t, []byte("ok"), okValue)
 			}
 			// check block gas is always consumed
-			baseGas := uint64(52864) // baseGas is the gas consumed before tx msg
+			baseGas := uint64(51822) // baseGas is the gas consumed before tx msg
 			expGasConsumed := addUint64Saturating(tc.gasToConsume, baseGas)
 			if expGasConsumed > txtypes.MaxGasWanted {
 				// capped by gasLimit

x/auth/ante/basic.go

@@ -53,14 +53,15 @@ func (vmd ValidateMemoDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate
 		return ctx, sdkerrors.Wrap(sdkerrors.ErrTxDecode, "invalid transaction type")
 	}
 
-	params := vmd.ak.GetParams(ctx)
-
 	memoLength := len(memoTx.GetMemo())
-	if uint64(memoLength) > params.MaxMemoCharacters {
-		return ctx, sdkerrors.Wrapf(sdkerrors.ErrMemoTooLarge,
-			"maximum number of characters is %d but received %d characters",
-			params.MaxMemoCharacters, memoLength,
-		)
+	if memoLength > 0 {
+		params := vmd.ak.GetParams(ctx)
+		if uint64(memoLength) > params.MaxMemoCharacters {
+			return ctx, sdkerrors.Wrapf(sdkerrors.ErrMemoTooLarge,
+				"maximum number of characters is %d but received %d characters",
+				params.MaxMemoCharacters, memoLength,
+			)
+		}
 	}
 
 	return next(ctx, tx, simulate)