fix: remove potential runtime panic in x/feegrant

CHANGELOG.md

@@ -104,6 +104,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (global) [\#694](https://github.com/line/lbm-sdk/pull/694) replace deprecated functions since go 1.16 or 1.17
 * (x/bankplus) [\#705](https://github.com/line/lbm-sdk/pull/705) add missing blockedAddr checking in bankplus
 * (x/foundation) [\#712](https://github.com/line/lbm-sdk/pull/712) fix x/foundation EndBlocker
+* (x/feegrant) [\#720](https://github.com/line/lbm-sdk/pull/720) remove potential runtime panic in x/feegrant
 * (baseapp) [\#724](https://github.com/line/lbm-sdk/pull/724) add checking pubkey type from validator params
 * (x/staking) [\#726](https://github.com/line/lbm-sdk/pull/726) check allowedList size in StakeAuthorization.Accept()
 * (x/staking) [\#728](https://github.com/line/lbm-sdk/pull/728) fix typo in unbondingToUnbonded() panic

x/feegrant/filtered_fee.go

@@ -53,11 +53,14 @@ func (a *AllowedMsgAllowance) GetAllowance() (FeeAllowanceI, error) {
 // SetAllowance sets allowed fee allowance.
 func (a *AllowedMsgAllowance) SetAllowance(allowance FeeAllowanceI) error {
 	var err error
-	a.Allowance, err = types.NewAnyWithValue(allowance.(proto.Message))
-	if err != nil {
+	protoAllowance, ok := allowance.(proto.Message)
+	if !ok {
 		return sdkerrors.Wrapf(sdkerrors.ErrPackAny, "cannot proto marshal %T", allowance)
 	}
-
+	a.Allowance, err = types.NewAnyWithValue(protoAllowance)
+	if err != nil {
+		return sdkerrors.Wrapf(sdkerrors.ErrPackAny, "cannot proto marshal %T", protoAllowance)
+	}
 	return nil
 }
 

x/feegrant/filtered_fee_test.go

@@ -4,6 +4,7 @@ import (
 	"testing"
 	"time"
 
+	proto "github.com/gogo/protobuf/proto"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
@@ -188,3 +189,73 @@ func TestFilteredFeeValidAllow(t *testing.T) {
 		})
 	}
 }
+
+// invalidInterfaceAllowance does not implement proto.Message
+type invalidInterfaceAllowance struct {
+}
+
+// compilation time interface implementation check
+var _ feegrant.FeeAllowanceI = (*invalidInterfaceAllowance)(nil)
+
+func (i invalidInterfaceAllowance) Accept(ctx sdk.Context, fee sdk.Coins, msgs []sdk.Msg) (remove bool, err error) {
+	return false, nil
+}
+
+func (i invalidInterfaceAllowance) ValidateBasic() error {
+	return nil
+}
+
+// invalidProtoAllowance can not run proto.Marshal
+type invalidProtoAllowance struct {
+	invalidInterfaceAllowance
+}
+
+// compilation time interface implementation check
+var _ feegrant.FeeAllowanceI = (*invalidProtoAllowance)(nil)
+var _ proto.Message = (*invalidProtoAllowance)(nil)
+
+func (i invalidProtoAllowance) Reset() {
+}
+
+func (i invalidProtoAllowance) String() string {
+	return ""
+}
+
+func (i invalidProtoAllowance) ProtoMessage() {
+}
+
+func TestSetAllowance(t *testing.T) {
+	cases := map[string]struct {
+		allowance feegrant.FeeAllowanceI
+		valid     bool
+	}{
+		"valid allowance": {
+			allowance: &feegrant.BasicAllowance{},
+			valid:     true,
+		},
+		"invalid interface allowance": {
+			allowance: &invalidInterfaceAllowance{},
+			valid:     false,
+		},
+		"empty allowance": {
+			allowance: (*invalidProtoAllowance)(nil),
+			valid:     false,
+		},
+	}
+
+	for name, tc := range cases {
+		t.Run(name, func(t *testing.T) {
+			allowance := &feegrant.BasicAllowance{}
+			msgs := []string{sdk.MsgTypeURL(&banktypes.MsgSend{})}
+			allowed, err := feegrant.NewAllowedMsgAllowance(allowance, msgs)
+			require.NoError(t, err)
+			require.NotNil(t, allowed)
+			err = allowed.SetAllowance(tc.allowance)
+			if tc.valid {
+				require.NoError(t, err)
+			} else {
+				require.Error(t, err)
+			}
+		})
+	}
+}