fix(x/auth/ante): deduct fees to the decorator's configured recipient module

CHANGELOG.md

@@ -55,6 +55,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### Bug Fixes
 
+* (x/auth/ante) [#26813](https://github.com/cosmos/cosmos-sdk/pull/26813) `DeductFeeDecorator` now deducts fees to the recipient module it was configured with. Previously it used the package-level `FeeRecipientModule`, which every `NewDeductFeeDecorator` call reset to `fee_collector`, so building a second ante chain silently redirected the fees of a decorator configured via `WithFeeRecipientModule`.
 * (client/tx) [#26759](https://github.com/cosmos/cosmos-sdk/issues/26759) Populate the multisig bit array in simulation txs so `--gas auto` works for multisig senders.
 * (blockstm) [#26772](https://github.com/cosmos/cosmos-sdk/pull/26772) Panic with a descriptive error when accessing an unregistered store instead of silently using store index zero.
 * (x/genutil) [#26741](https://github.com/cosmos/cosmos-sdk/issues/26741) Preserve vote extension enable height when exporting genesis state.

x/auth/ante/fee.go

@@ -11,11 +11,12 @@ import (
 	"github.com/cosmos/cosmos-sdk/x/auth/types"
 )
 
-// FeeRecipientModule holds the module name that receives deducted tx fees.
-// It is set by NewDeductFeeDecorator (default: fee_collector) and updated by
-// WithFeeRecipientModule. Other modules can read this to verify that fees are
-// being routed to the expected destination.
-var FeeRecipientModule string
+// FeeRecipientModule holds the module name that receives deducted tx fees
+// (default: fee_collector). It is updated by WithFeeRecipientModule and used
+// by DeductFees. Other modules can read this to verify that fees are being
+// routed to the expected destination. DeductFeeDecorator itself always
+// deducts to the recipient it was configured with.
+var FeeRecipientModule = types.FeeCollectorName
 
 // TxFeeChecker check if the provided fee is enough and returns the effective fee and tx priority,
 // the effective fee should be deducted later, and the priority should be returned in abci response.
@@ -38,8 +39,6 @@ func NewDeductFeeDecorator(ak AccountKeeper, bk types.BankKeeper, fk FeegrantKee
 		tfc = checkTxFeeWithValidatorMinGasPrices
 	}
 
-	FeeRecipientModule = types.FeeCollectorName
-
 	return DeductFeeDecorator{
 		accountKeeper:      ak,
 		bankKeeper:         bk,
@@ -130,7 +129,7 @@ func (dfd DeductFeeDecorator) checkDeductFee(ctx sdk.Context, sdkTx sdk.Tx, fee
 
 	// deduct the fees
 	if !fee.IsZero() {
-		err := DeductFees(dfd.bankKeeper, ctx, deductFeesFromAcc, fee)
+		err := deductFeesToModule(dfd.bankKeeper, ctx, deductFeesFromAcc, fee, dfd.feeRecipientModule)
 		if err != nil {
 			return err
 		}
@@ -151,11 +150,17 @@ func (dfd DeductFeeDecorator) checkDeductFee(ctx sdk.Context, sdkTx sdk.Tx, fee
 // DeductFees deducts fees from the given account and sends them to the
 // module configured via FeeRecipientModule.
 func DeductFees(bankKeeper types.BankKeeper, ctx sdk.Context, acc sdk.AccountI, fees sdk.Coins) error {
+	return deductFeesToModule(bankKeeper, ctx, acc, fees, FeeRecipientModule)
+}
+
+// deductFeesToModule deducts fees from the given account and sends them to
+// the given module account.
+func deductFeesToModule(bankKeeper types.BankKeeper, ctx sdk.Context, acc sdk.AccountI, fees sdk.Coins, recipientModule string) error {
 	if !fees.IsValid() {
 		return errorsmod.Wrapf(sdkerrors.ErrInsufficientFee, "invalid fee amount: %s", fees)
 	}
 
-	err := bankKeeper.SendCoinsFromAccountToModule(ctx, acc.GetAddress(), FeeRecipientModule, fees)
+	err := bankKeeper.SendCoinsFromAccountToModule(ctx, acc.GetAddress(), recipientModule, fees)
 	if err != nil {
 		return errorsmod.Wrapf(sdkerrors.ErrInsufficientFunds, "%s", err.Error())
 	}

x/auth/ante/fee_test.go

@@ -196,3 +196,28 @@ func TestDeductFees_WithFeeRecipientModule(t *testing.T) {
 		})
 	}
 }
+
+// A decorator configured with a custom fee recipient must keep using it even
+// when another DeductFeeDecorator is constructed afterwards.
+func TestDeductFees_RecipientNotClobberedByLaterDecorator(t *testing.T) {
+	s := SetupTestSuite(t, false)
+	s.txBuilder = s.clientCtx.TxConfig.NewTxBuilder()
+	accs := s.CreateTestAccounts(1)
+
+	msg := testdata.NewTestMsg(accs[0].acc.GetAddress())
+	feeAmount := testdata.NewTestFeeAmount()
+	require.NoError(t, s.txBuilder.SetMsgs(msg))
+	s.txBuilder.SetFeeAmount(feeAmount)
+	s.txBuilder.SetGasLimit(testdata.NewTestGasLimit())
+	tx, err := s.CreateTestTx(s.ctx, []cryptotypes.PrivKey{accs[0].priv}, []uint64{0}, []uint64{0}, s.ctx.ChainID(), signing.SignMode_SIGN_MODE_DIRECT)
+	require.NoError(t, err)
+
+	custom := ante.NewDeductFeeDecorator(s.accountKeeper, s.bankKeeper, nil, nil).WithFeeRecipientModule("mint")
+	// e.g. a second ante chain built by the app
+	_ = ante.NewDeductFeeDecorator(s.accountKeeper, s.bankKeeper, nil, nil)
+
+	s.bankKeeper.EXPECT().SendCoinsFromAccountToModule(gomock.Any(), accs[0].acc.GetAddress(), "mint", feeAmount).Return(nil)
+
+	_, err = sdk.ChainAnteDecorators(custom)(s.ctx, tx, false)
+	require.NoError(t, err)
+}