From 173a0abab4cde6f30b6263372884eda77c986423 Mon Sep 17 00:00:00 2001
From: Michael Sproul <michael@sigmaprime.io>
Date: Tue, 13 Dec 2022 17:03:21 +1100
Subject: [PATCH] Fix `Withdrawal` serialisation and check address change fork
 (#3789)

* Disallow address changes before Capella

* Quote u64s in Withdrawal serialisation
---
 beacon_node/beacon_chain/src/beacon_chain.rs | 7 +++++++
 beacon_node/beacon_chain/src/errors.rs       | 1 +
 consensus/types/src/withdrawal.rs            | 2 ++
 3 files changed, 10 insertions(+)

diff --git a/beacon_node/beacon_chain/src/beacon_chain.rs b/beacon_node/beacon_chain/src/beacon_chain.rs
index 7841f53e7..0bbbe9235 100644
--- a/beacon_node/beacon_chain/src/beacon_chain.rs
+++ b/beacon_node/beacon_chain/src/beacon_chain.rs
@@ -2191,7 +2191,14 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
     ) -> Result<ObservationOutcome<SignedBlsToExecutionChange, T::EthSpec>, Error> {
         #[cfg(feature = "withdrawals-processing")]
         {
+            let current_fork = self.spec.fork_name_at_slot::<T::EthSpec>(self.slot()?);
+            if let ForkName::Base | ForkName::Altair | ForkName::Merge = current_fork {
+                // Disallow BLS to execution changes prior to the Capella fork.
+                return Err(Error::BlsToExecutionChangeBadFork(current_fork));
+            }
+
             let wall_clock_state = self.wall_clock_state()?;
+
             Ok(self
                 .observed_bls_to_execution_changes
                 .lock()
diff --git a/beacon_node/beacon_chain/src/errors.rs b/beacon_node/beacon_chain/src/errors.rs
index 60282426a..3a2e4a0bc 100644
--- a/beacon_node/beacon_chain/src/errors.rs
+++ b/beacon_node/beacon_chain/src/errors.rs
@@ -206,6 +206,7 @@ pub enum BeaconChainError {
     MissingPersistedForkChoice,
     CommitteePromiseFailed(oneshot_broadcast::Error),
     MaxCommitteePromises(usize),
+    BlsToExecutionChangeBadFork(ForkName),
 }
 
 easy_from_to!(SlotProcessingError, BeaconChainError);
diff --git a/consensus/types/src/withdrawal.rs b/consensus/types/src/withdrawal.rs
index 10530dcb5..6f14cf1c5 100644
--- a/consensus/types/src/withdrawal.rs
+++ b/consensus/types/src/withdrawal.rs
@@ -12,8 +12,10 @@ use tree_hash_derive::TreeHash;
 pub struct Withdrawal {
     #[serde(with = "eth2_serde_utils::quoted_u64")]
     pub index: u64,
+    #[serde(with = "eth2_serde_utils::quoted_u64")]
     pub validator_index: u64,
     pub address: Address,
+    #[serde(with = "eth2_serde_utils::quoted_u64")]
     pub amount: u64,
 }