From 521be2b7576e94a0ca01107cc08d0b3a35a96dee Mon Sep 17 00:00:00 2001
From: Eitan Seri-Levi <eserilev@gmail.com>
Date: Wed, 17 Sep 2025 18:33:42 -0700
Subject: [PATCH] Prevent silently dropping cell proof chunks (#8023)

Co-Authored-By: Eitan Seri- Levi <eserilev@gmail.com>
---
 beacon_node/beacon_chain/src/kzg_utils.rs  | 7 +++++++
 beacon_node/http_api/src/publish_blocks.rs | 2 +-
 consensus/types/src/data_column_sidecar.rs | 1 +
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/beacon_node/beacon_chain/src/kzg_utils.rs b/beacon_node/beacon_chain/src/kzg_utils.rs
index 2147ed5966..ad669e1729 100644
--- a/beacon_node/beacon_chain/src/kzg_utils.rs
+++ b/beacon_node/beacon_chain/src/kzg_utils.rs
@@ -174,6 +174,13 @@ pub fn blobs_to_data_column_sidecars<E: EthSpec>(
     let kzg_commitments_inclusion_proof = block.message().body().kzg_commitments_merkle_proof()?;
     let signed_block_header = block.signed_block_header();
 
+    if cell_proofs.len() != blobs.len() * E::number_of_columns() {
+        return Err(DataColumnSidecarError::InvalidCellProofLength {
+            expected: blobs.len() * E::number_of_columns(),
+            actual: cell_proofs.len(),
+        });
+    }
+
     let proof_chunks = cell_proofs
         .chunks_exact(E::number_of_columns())
         .collect::<Vec<_>>();
diff --git a/beacon_node/http_api/src/publish_blocks.rs b/beacon_node/http_api/src/publish_blocks.rs
index b6411167d9..05a4a4b7a4 100644
--- a/beacon_node/http_api/src/publish_blocks.rs
+++ b/beacon_node/http_api/src/publish_blocks.rs
@@ -412,7 +412,7 @@ fn build_data_columns<T: BeaconChainTypes>(
             error!(
                 error = ?e,
                 %slot,
-                "Invalid data column - not publishing block"
+                "Invalid data column - not publishing data columns"
             );
             warp_utils::reject::custom_bad_request(format!("{e:?}"))
         })?;
diff --git a/consensus/types/src/data_column_sidecar.rs b/consensus/types/src/data_column_sidecar.rs
index 57f7a88e19..2272b1695c 100644
--- a/consensus/types/src/data_column_sidecar.rs
+++ b/consensus/types/src/data_column_sidecar.rs
@@ -143,6 +143,7 @@ pub enum DataColumnSidecarError {
     PreDeneb,
     SszError(SszError),
     BuildSidecarFailed(String),
+    InvalidCellProofLength { expected: usize, actual: usize },
 }
 
 impl From<ArithError> for DataColumnSidecarError {