Fix Voluntary Exits Panic (#5688)

* add fix and regression test
* Update beacon-chain/rpc/validator/exit_test.go

Co-Authored-By: Shay Zluf <thezluf@gmail.com>
* Update beacon-chain/rpc/validator/exit_test.go

Co-Authored-By: Shay Zluf <thezluf@gmail.com>
* Update exit_test.go

beacon-chain/rpc/validator/exit.go

@@ -9,6 +9,7 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/feed"
 	opfeed "github.com/prysmaticlabs/prysm/beacon-chain/core/feed/operation"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/shared/params"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
 )
@@ -22,6 +23,12 @@ func (vs *Server) ProposeExit(ctx context.Context, req *ethpb.SignedVoluntaryExi
 	if err != nil {
 		return nil, status.Errorf(codes.Internal, "Could not get head state: %v", err)
 	}
+	if req.Exit == nil {
+		return nil, status.Error(codes.InvalidArgument, "voluntary exit does not exist")
+	}
+	if req.Signature == nil || len(req.Signature) != params.BeaconConfig().BLSSignatureLength {
+		return nil, status.Error(codes.InvalidArgument, "invalid signature provided")
+	}
 
 	// Confirm the validator is eligible to exit with the parameters provided.
 	val, err := s.ValidatorAtIndex(req.Exit.ValidatorIndex)

beacon-chain/rpc/validator/exit_test.go

@@ -5,6 +5,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/prysmaticlabs/prysm/shared/bytesutil"
 	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
 	"github.com/prysmaticlabs/go-ssz"
 	mockChain "github.com/prysmaticlabs/prysm/beacon-chain/blockchain/testing"
@@ -110,3 +111,87 @@ func TestSub(t *testing.T) {
 		}
 	}
 }
+
+func TestProposeExit_NoPanic(t *testing.T) {
+	db := dbutil.SetupDB(t)
+	defer dbutil.TeardownDB(t, db)
+	ctx := context.Background()
+	testutil.ResetCache()
+	deposits, keys, err := testutil.DeterministicDepositsAndKeys(params.BeaconConfig().MinGenesisActiveValidatorCount)
+	if err != nil {
+		t.Fatal(err)
+	}
+	beaconState, err := state.GenesisBeaconState(deposits, 0, &ethpb.Eth1Data{BlockHash: make([]byte, 32)})
+	if err != nil {
+		t.Fatal(err)
+	}
+	block := blk.NewGenesisBlock([]byte{})
+	if err := db.SaveBlock(ctx, block); err != nil {
+		t.Fatalf("Could not save genesis block: %v", err)
+	}
+	genesisRoot, err := ssz.HashTreeRoot(block.Block)
+	if err != nil {
+		t.Fatalf("Could not get signing root %v", err)
+	}
+
+	// Set genesis time to be 100 epochs ago.
+	genesisTime := time.Now().Add(time.Duration(-100*int64(params.BeaconConfig().SecondsPerSlot*params.BeaconConfig().SlotsPerEpoch)) * time.Second)
+	mockChainService := &mockChain.ChainService{State: beaconState, Root: genesisRoot[:], Genesis: genesisTime}
+	server := &Server{
+		BeaconDB:           db,
+		HeadFetcher:        mockChainService,
+		SyncChecker:        &mockSync.Sync{IsSyncing: false},
+		GenesisTimeFetcher: mockChainService,
+		StateNotifier:      mockChainService.StateNotifier(),
+		OperationNotifier:  mockChainService.OperationNotifier(),
+		ExitPool:           voluntaryexits.NewPool(),
+		P2P:                mockp2p.NewTestP2P(t),
+	}
+
+	// Subscribe to operation notifications.
+	opChannel := make(chan *feed.Event, 1024)
+	opSub := server.OperationNotifier.OperationFeed().Subscribe(opChannel)
+	defer opSub.Unsubscribe()
+
+	req := &ethpb.SignedVoluntaryExit{}
+	_, err = server.ProposeExit(context.Background(), req)
+	if err == nil {
+		t.Fatal("Expected error for no exit existing")
+	}
+
+	// Send the request, expect a result on the state feed.
+	epoch := uint64(2048)
+	validatorIndex := uint64(0)
+	req = &ethpb.SignedVoluntaryExit{
+		Exit: &ethpb.VoluntaryExit{
+			Epoch:          epoch,
+			ValidatorIndex: validatorIndex,
+		},
+	}
+
+	_, err = server.ProposeExit(context.Background(), req)
+	if err == nil {
+		t.Fatal("Expected error for no signature exists")
+	}
+	req.Signature = bytesutil.FromBytes48([48]byte{})
+
+	_, err = server.ProposeExit(context.Background(), req)
+	if err == nil {
+		t.Fatal("Expected error for invalid signature length")
+	}
+
+	domain, err := helpers.Domain(beaconState.Fork(), epoch, params.BeaconConfig().DomainVoluntaryExit, beaconState.GenesisValidatorRoot())
+	if err != nil {
+		t.Fatal(err)
+	}
+	sigRoot, err := helpers.ComputeSigningRoot(req.Exit, domain)
+	if err != nil {
+		t.Fatalf("Could not compute signing root: %v", err)
+	}
+	req.Signature = keys[0].Sign(sigRoot[:]).Marshal()
+
+	_, err = server.ProposeExit(context.Background(), req)
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+}