impl 5281 gossip verification check

beacon_node/beacon_chain/src/payload_attestation_verification/gossip_verified_payload_attestation.rs

@@ -70,13 +70,21 @@ impl<T: BeaconChainTypes> VerifiedPayloadAttestationMessage<T> {
         // 2. Blocks we've seen that are invalid (REJECT).
         // Presently both cases return IGNORE.
         let beacon_block_root = payload_attestation_message.data.beacon_block_root;
-        if ctx
+        let block = ctx
             .canonical_head
             .fork_choice_read_lock()
             .get_block(&beacon_block_root)
-            .is_none()
-        {
-            return Err(Error::UnknownHeadBlock { beacon_block_root });
+            .ok_or(Error::UnknownHeadBlock { beacon_block_root })?;
+
+        // [IGNORE] The block referenced by `data.beacon_block_root` is at slot `data.slot`, i.e.
+        // the block has `block.slot == data.slot`. A PTC member assigned to an empty slot must not
+        // attest, so ignore messages that reference an earlier block.
+        if block.slot != slot {
+            return Err(Error::BlockNotAtSlot {
+                beacon_block_root,
+                block_slot: block.slot,
+                data_slot: slot,
+            });
         }
 
         let message_epoch = slot.epoch(T::EthSpec::slots_per_epoch());

beacon_node/beacon_chain/src/payload_attestation_verification/mod.rs

@@ -60,6 +60,19 @@ pub enum Error {
     /// The attestation points to a block we have not yet imported. It's unclear if the
     /// attestation is valid or not.
     UnknownHeadBlock { beacon_block_root: Hash256 },
+    /// The block referenced by `data.beacon_block_root` is not at slot `data.slot`, i.e. the
+    /// PTC member's assigned slot was empty (the message references the last canonical block at
+    /// an earlier slot).
+    ///
+    /// ## Peer scoring
+    ///
+    /// PTC members should not attest for empty slots, so we
+    /// ignore the message.
+    BlockNotAtSlot {
+        beacon_block_root: Hash256,
+        block_slot: Slot,
+        data_slot: Slot,
+    },
     /// The validator index is not a member of the PTC for this slot.
     ///
     /// ## Peer scoring

beacon_node/beacon_chain/src/payload_attestation_verification/tests.rs

@@ -167,6 +167,25 @@ fn unknown_head_block() {
     );
 }
 
+#[test]
+fn block_not_at_slot() {
+    if !fork_name_from_env().is_some_and(|f| f.gloas_enabled()) {
+        return;
+    }
+    let ctx = TestContext::new();
+    let gossip = ctx.gossip_ctx();
+
+    // The genesis block is at slot 0, but the message claims slot 1. A PTC member assigned to an
+    // empty slot must not attest, so this must be ignored (per consensus-specs #5281).
+    let msg = make_payload_attestation(Slot::new(1), 0, ctx.genesis_block_root);
+    let result = VerifiedPayloadAttestationMessage::new(msg, &gossip);
+    assert!(
+        matches!(result, Err(PayloadAttestationError::BlockNotAtSlot { .. })),
+        "expected BlockNotAtSlot, got: {:?}",
+        result
+    );
+}
+
 #[test]
 fn not_in_ptc() {
     if !fork_name_from_env().is_some_and(|f| f.gloas_enabled()) {
@@ -174,7 +193,9 @@ fn not_in_ptc() {
     }
     let ctx = TestContext::new();
     let gossip = ctx.gossip_ctx();
-    let slot = Slot::new(1);
+    // The genesis block is at slot 0, so attest at slot 0 to satisfy the `block.slot == data.slot`
+    // gossip rule. Slot 0 is still within the propagation range at the current slot.
+    let slot = Slot::new(0);
 
     let ptc_members = ctx.ptc_members(slot);
     let non_ptc_validator = (0..NUM_VALIDATORS as u64)
@@ -196,7 +217,9 @@ fn invalid_signature() {
     }
     let ctx = TestContext::new();
     let gossip = ctx.gossip_ctx();
-    let slot = Slot::new(1);
+    // The genesis block is at slot 0, so attest at slot 0 to satisfy the `block.slot == data.slot`
+    // gossip rule. Slot 0 is still within the propagation range at the current slot.
+    let slot = Slot::new(0);
 
     let ptc_members = ctx.ptc_members(slot);
     let validator_index = ptc_members[0] as u64;
@@ -216,7 +239,9 @@ fn valid_payload_attestation() {
     }
     let ctx = TestContext::new();
     let gossip = ctx.gossip_ctx();
-    let slot = Slot::new(1);
+    // The genesis block is at slot 0, so attest at slot 0 to satisfy the `block.slot == data.slot`
+    // gossip rule. Slot 0 is still within the propagation range at the current slot.
+    let slot = Slot::new(0);
 
     let ptc_members = ctx.ptc_members(slot);
     let validator_index = ptc_members[0] as u64;
@@ -243,7 +268,9 @@ fn duplicate_after_valid() {
     }
     let ctx = TestContext::new();
     let gossip = ctx.gossip_ctx();
-    let slot = Slot::new(1);
+    // The genesis block is at slot 0, so attest at slot 0 to satisfy the `block.slot == data.slot`
+    // gossip rule. Slot 0 is still within the propagation range at the current slot.
+    let slot = Slot::new(0);
 
     let ptc_members = ctx.ptc_members(slot);
     let validator_index = ptc_members[0] as u64;

beacon_node/network/src/network_beacon_processor/gossip_methods.rs

@@ -4003,6 +4003,14 @@ impl<T: BeaconChainTypes> NetworkBeaconProcessor<T> {
                 );
                 self.propagate_validation_result(message_id, peer_id, MessageAcceptance::Ignore);
             }
+            PayloadAttestationError::BlockNotAtSlot { .. } => {
+                debug!(
+                    %peer_id,
+                    %message_slot,
+                    "Payload attestation references block at wrong slot"
+                );
+                self.propagate_validation_result(message_id, peer_id, MessageAcceptance::Ignore);
+            }
             PayloadAttestationError::NotInPTC { .. } => {
                 self.propagate_validation_result(message_id, peer_id, MessageAcceptance::Reject);
                 self.gossip_penalize_peer(

consensus/proto_array/src/proto_array.rs

@@ -1539,11 +1539,11 @@ impl ProtoArray {
         // considered available when either a majority have voted true or not enough votes have
         // been cast either way.
         if proto_node.payload_data_availability::<E>(false)? {
-            return Ok(false)
+            return Ok(false);
         }
-        
+
         if proto_node.payload_timeliness::<E>(false)? {
-            return Ok(false)
+            return Ok(false);
         }
 
         Ok(true)