gossip attestation validation: handle no committee error

packages/beacon-node/src/chain/validation/aggregateAndProof.ts

@@ -29,6 +29,7 @@ export async function validateGossipAggregateAndProof(
   const attData = aggregate.data;
   const attDataRoot = toHexString(ssz.phase0.AttestationData.hashTreeRoot(attData));
   const attSlot = attData.slot;
+  const attIndex = attData.index;
   const attEpoch = computeEpochAtSlot(attSlot);
   const attTarget = attData.target;
   const targetEpoch = attTarget.epoch;
@@ -84,7 +85,8 @@ export async function validateGossipAggregateAndProof(
       });
     });
 
-  const committeeIndices = getCommitteeIndices(attHeadState, attSlot, attData.index);
+  const committeeIndices: number[] = getCommitteeIndices(attHeadState, attSlot, attIndex);
+
   const attestingIndices = aggregate.aggregationBits.intersectValues(committeeIndices);
   const indexedAttestation: phase0.IndexedAttestation = {
     attestingIndices,

packages/beacon-node/src/chain/validation/attestation.ts

@@ -89,6 +89,7 @@ export async function validateGossipAttestation(
   // -- i.e. data.index < get_committee_count_per_slot(state, data.target.epoch)
   const attIndex = attData.index;
   const committeeIndices = getCommitteeIndices(attHeadState, attSlot, attIndex);
+
   const validatorIndex = committeeIndices[bitIndex];
 
   // [REJECT] The number of aggregation bits matches the committee size
@@ -284,7 +285,18 @@ export function getCommitteeIndices(
   attestationSlot: Slot,
   attestationIndex: number
 ): number[] {
-  const {committees} = attestationTargetState.epochCtx.getShufflingAtSlot(attestationSlot);
+  const shuffling = attestationTargetState.epochCtx.getShufflingAtSlotOrNull(attestationSlot);
+  if (shuffling === null) {
+    // this may come from an out-of-synced node, the spec did not define it so should not REJECT
+    // see https://github.com/ChainSafe/lodestar/issues/4396
+    throw new AttestationError(GossipAction.IGNORE, {
+      code: AttestationErrorCode.NO_COMMITTEE_FOR_SLOT_AND_INDEX,
+      index: attestationIndex,
+      slot: attestationSlot,
+    });
+  }
+
+  const {committees} = shuffling;
   const slotCommittees = committees[attestationSlot % SLOTS_PER_EPOCH];
 
   if (attestationIndex >= slotCommittees.length) {

packages/beacon-node/src/network/gossip/validation/index.ts

@@ -88,7 +88,8 @@ function getGossipValidatorFn<K extends GossipType>(
       return MessageAcceptance.Accept;
     } catch (e) {
       if (!(e instanceof GossipActionError)) {
-        logger.error(`Gossip validation ${type} threw a non-GossipActionError`, {}, e as Error);
+        // not deserve to log error here, it looks too dangerous to users
+        logger.debug(`Gossip validation ${type} threw a non-GossipActionError`, {}, e as Error);
         return MessageAcceptance.Ignore;
       }
 

packages/beacon-node/test/unit/chain/validation/aggregateAndProof.test.ts

@@ -1,6 +1,7 @@
 import {toHexString} from "@chainsafe/ssz";
 import {SLOTS_PER_EPOCH} from "@lodestar/params";
 import {phase0, ssz} from "@lodestar/types";
+import {processSlots} from "@lodestar/state-transition";
 import {IBeaconChain} from "../../../../src/chain/index.js";
 import {AttestationErrorCode} from "../../../../src/chain/errors/index.js";
 import {validateGossipAggregateAndProof} from "../../../../src/chain/validation/index.js";
@@ -12,6 +13,7 @@ import {
   getAggregateAndProofValidData,
   AggregateAndProofValidDataOpts,
 } from "../../../utils/validationData/aggregateAndProof.js";
+import {IStateRegenerator} from "../../../../src/chain/regen/interface.js";
 
 describe("chain / validation / aggregateAndProof", () => {
   const vc = 64;
@@ -108,6 +110,22 @@ describe("chain / validation / aggregateAndProof", () => {
     await expectError(chain, signedAggregateAndProof, AttestationErrorCode.INVALID_TARGET_ROOT);
   });
 
+  it("NO_COMMITTEE_FOR_SLOT_AND_INDEX", async () => {
+    const {chain, signedAggregateAndProof} = getValidData();
+    // slot is out of the commitee range
+    // simulate https://github.com/ChainSafe/lodestar/issues/4396
+    // this way we cannot get committeeIndices
+    const committeeState = processSlots(
+      getState(),
+      signedAggregateAndProof.message.aggregate.data.slot + 2 * SLOTS_PER_EPOCH
+    );
+    (chain as {regen: IStateRegenerator}).regen = ({
+      getState: async () => committeeState,
+    } as Partial<IStateRegenerator>) as IStateRegenerator;
+
+    await expectError(chain, signedAggregateAndProof, AttestationErrorCode.NO_COMMITTEE_FOR_SLOT_AND_INDEX);
+  });
+
   it("EMPTY_AGGREGATION_BITFIELD", async () => {
     const {chain, signedAggregateAndProof} = getValidData();
     // Unset all aggregationBits

packages/beacon-node/test/unit/chain/validation/attestation.test.ts

@@ -1,6 +1,7 @@
 import {SLOTS_PER_EPOCH} from "@lodestar/params";
 import {phase0} from "@lodestar/types";
 import {BitArray} from "@chainsafe/ssz";
+import {processSlots} from "@lodestar/state-transition";
 import {IBeaconChain} from "../../../../src/chain/index.js";
 import {AttestationErrorCode} from "../../../../src/chain/errors/index.js";
 import {validateGossipAttestation} from "../../../../src/chain/validation/index.js";
@@ -9,6 +10,7 @@ import {expectRejectedWithLodestarError} from "../../../utils/errors.js";
 import {generateTestCachedBeaconStateOnlyValidators} from "../../../../../state-transition/test/perf/util.js";
 import {memoOnce} from "../../../utils/cache.js";
 import {getAttestationValidData, AttestationValidDataOpts} from "../../../utils/validationData/attestation.js";
+import {IStateRegenerator} from "../../../../src/chain/regen/interface.js";
 
 describe("chain / validation / attestation", () => {
   const vc = 64;
@@ -97,6 +99,19 @@ describe("chain / validation / attestation", () => {
     await expectError(chain, attestation, subnet, AttestationErrorCode.INVALID_TARGET_ROOT);
   });
 
+  it("NO_COMMITTEE_FOR_SLOT_AND_INDEX", async () => {
+    const {chain, attestation, subnet} = getValidData();
+    // slot is out of the commitee range
+    // simulate https://github.com/ChainSafe/lodestar/issues/4396
+    // this way we cannot get committeeIndices
+    const committeeState = processSlots(getState(), attestation.data.slot + 2 * SLOTS_PER_EPOCH);
+    (chain as {regen: IStateRegenerator}).regen = ({
+      getState: async () => committeeState,
+    } as Partial<IStateRegenerator>) as IStateRegenerator;
+
+    await expectError(chain, attestation, subnet, AttestationErrorCode.NO_COMMITTEE_FOR_SLOT_AND_INDEX);
+  });
+
   it("WRONG_NUMBER_OF_AGGREGATION_BITS", async () => {
     const {chain, attestation, subnet} = getValidData();
     // Increase the length of aggregationBits beyond the committee size

packages/state-transition/src/cache/epochContext.ts

@@ -709,15 +709,29 @@ export class EpochContext {
     return this.getShufflingAtEpoch(epoch);
   }
 
+  getShufflingAtSlotOrNull(slot: Slot): IEpochShuffling | null {
+    const epoch = computeEpochAtSlot(slot);
+    return this.getShufflingAtEpochOrNull(epoch);
+  }
+
   getShufflingAtEpoch(epoch: Epoch): IEpochShuffling {
+    const shuffling = this.getShufflingAtEpochOrNull(epoch);
+    if (shuffling === null) {
+      throw new Error(`Requesting slot committee out of range epoch: ${epoch} current: ${this.currentShuffling.epoch}`);
+    }
+
+    return shuffling;
+  }
+
+  getShufflingAtEpochOrNull(epoch: Epoch): IEpochShuffling | null {
     if (epoch === this.previousShuffling.epoch) {
       return this.previousShuffling;
     } else if (epoch === this.currentShuffling.epoch) {
       return this.currentShuffling;
     } else if (epoch === this.nextShuffling.epoch) {
       return this.nextShuffling;
     } else {
-      throw new Error(`Requesting slot committee out of range epoch: ${epoch} current: ${this.currentShuffling.epoch}`);
+      return null;
     }
   }