From a8c49c50adedf15fa82b411533f5a8c53d0b4fe3 Mon Sep 17 00:00:00 2001
From: Kaan <kilickaan1998@gmail.com>
Date: Mon, 26 Jul 2021 07:50:40 +0200
Subject: [PATCH] v1alpha1 validators: catch possible reqState nil case (#9275)
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* v1alpha1 validators: catch possible reqState nil case

* Minor format of error log

Co-authored-by: terence tsao <terence@prysmaticlabs.com>
Co-authored-by: Radosław Kapka <rkapka@wp.pl>
---
 .../rpc/prysm/v1alpha1/beacon/validators.go   |  3 ++
 .../prysm/v1alpha1/beacon/validators_test.go  | 34 +++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/beacon-chain/rpc/prysm/v1alpha1/beacon/validators.go b/beacon-chain/rpc/prysm/v1alpha1/beacon/validators.go
index ed0a3aae7..df354ae16 100644
--- a/beacon-chain/rpc/prysm/v1alpha1/beacon/validators.go
+++ b/beacon-chain/rpc/prysm/v1alpha1/beacon/validators.go
@@ -228,6 +228,9 @@ func (bs *Server) ListValidators(
 	if err != nil {
 		return nil, status.Errorf(codes.Internal, "Could not get requested state: %v", err)
 	}
+	if reqState == nil || reqState.IsNil() {
+		return nil, status.Error(codes.Internal, "Requested state is nil")
+	}
 
 	s, err := helpers.StartSlot(requestedEpoch)
 	if err != nil {
diff --git a/beacon-chain/rpc/prysm/v1alpha1/beacon/validators_test.go b/beacon-chain/rpc/prysm/v1alpha1/beacon/validators_test.go
index 2aa43fc6e..a54be77a9 100644
--- a/beacon-chain/rpc/prysm/v1alpha1/beacon/validators_test.go
+++ b/beacon-chain/rpc/prysm/v1alpha1/beacon/validators_test.go
@@ -433,6 +433,40 @@ func TestServer_ListValidators_CannotRequestFutureEpoch(t *testing.T) {
 	assert.ErrorContains(t, wanted, err)
 }
 
+func TestServer_ListValidators_reqStateIsNil(t *testing.T) {
+	beaconDB := dbTest.SetupDB(t)
+	secondsPerEpoch := params.BeaconConfig().SecondsPerSlot * uint64(params.BeaconConfig().SlotsPerEpoch)
+	bs := &Server{
+		BeaconDB: beaconDB,
+		GenesisTimeFetcher: &mock.ChainService{
+			// We are in epoch 1.
+			Genesis: time.Now().Add(time.Duration(-1*int64(secondsPerEpoch)) * time.Second),
+		},
+		HeadFetcher: &mock.ChainService{
+			State: nil,
+		},
+		StateGen: &stategen.MockStateManager{
+			StatesBySlot: map[types.Slot]state.BeaconState{
+				0: nil,
+			},
+		},
+	}
+	// request uses HeadFetcher to get reqState.
+	req1 := &ethpb.ListValidatorsRequest{PageToken: strconv.Itoa(1), PageSize: 100}
+	wanted := "Requested state is nil"
+	_, err := bs.ListValidators(context.Background(), req1)
+	assert.ErrorContains(t, wanted, err)
+
+	// request uses StateGen to get reqState.
+	req2 := &ethpb.ListValidatorsRequest{
+		QueryFilter: &ethpb.ListValidatorsRequest_Genesis{},
+		PageToken:   strconv.Itoa(1),
+		PageSize:    100,
+	}
+	_, err = bs.ListValidators(context.Background(), req2)
+	assert.ErrorContains(t, wanted, err)
+}
+
 func TestServer_ListValidators_NoResults(t *testing.T) {
 	beaconDB := dbTest.SetupDB(t)