From 74cca27b2f8f5ebc5d7602838d9132f786c7773c Mon Sep 17 00:00:00 2001
From: Raul Jordan <raul@prysmaticlabs.com>
Date: Mon, 6 Apr 2020 23:08:30 -0500
Subject: [PATCH] Nil Checks in Process Attestation v0.11 (#5331)

* Started testing

* Bunch of fixes

* use-interop

* Sync with v0.11

* Uncomment wait for activation

* Move pending block queue from subscriber to validator pipeline

* passing tests

* nil checks to prevent panics

* lint

Co-authored-by: terence tsao <terence@prysmaticlabs.com>
---
 beacon-chain/blockchain/process_attestation.go   | 10 ++++++++++
 .../blockchain/process_attestation_helpers.go    | 16 ++++++++++------
 2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/beacon-chain/blockchain/process_attestation.go b/beacon-chain/blockchain/process_attestation.go
index c20d6dc6623..6aa0d593c2a 100644
--- a/beacon-chain/blockchain/process_attestation.go
+++ b/beacon-chain/blockchain/process_attestation.go
@@ -125,6 +125,16 @@ func (s *Service) onAttestation(ctx context.Context, a *ethpb.Attestation) ([]ui
 		}
 	}
 
+	if indexedAtt.AttestingIndices == nil {
+		return nil, errors.New("nil attesting indices")
+	}
+	if a.Data == nil {
+		return nil, errors.New("nil att data")
+	}
+	if a.Data.Target == nil {
+		return nil, errors.New("nil att target")
+	}
+
 	// Update forkchoice store with the new attestation for updating weight.
 	s.forkChoiceStore.ProcessAttestation(ctx, indexedAtt.AttestingIndices, bytesutil.ToBytes32(a.Data.BeaconBlockRoot), a.Data.Target.Epoch)
 
diff --git a/beacon-chain/blockchain/process_attestation_helpers.go b/beacon-chain/blockchain/process_attestation_helpers.go
index 3805b99555b..6f497a28f7e 100644
--- a/beacon-chain/blockchain/process_attestation_helpers.go
+++ b/beacon-chain/blockchain/process_attestation_helpers.go
@@ -130,14 +130,18 @@ func (s *Service) verifyAttestation(ctx context.Context, baseState *stateTrie.Be
 			var err error
 			if !featureconfig.Get().DisableNewStateMgmt {
 				aState, err = s.stateGen.StateByRoot(ctx, bytesutil.ToBytes32(a.Data.BeaconBlockRoot))
-				return nil, err
+				if err != nil {
+					return nil, err
+				}
+			} else {
+				aState, err = s.beaconDB.State(ctx, bytesutil.ToBytes32(a.Data.BeaconBlockRoot))
+				if err != nil {
+					return nil, err
+				}
 			}
-
-			aState, err = s.beaconDB.State(ctx, bytesutil.ToBytes32(a.Data.BeaconBlockRoot))
-			if err != nil {
-				return nil, err
+			if aState == nil {
+				return nil, fmt.Errorf("nil state for block root %#x", a.Data.BeaconBlockRoot)
 			}
-
 			epoch := helpers.SlotToEpoch(a.Data.Slot)
 			origSeed, err := helpers.Seed(baseState, epoch, params.BeaconConfig().DomainBeaconAttester)
 			if err != nil {