Reject Empty Bundles (#13798)

* reject it

* test

* add test case

beacon-chain/rpc/prysm/v1alpha1/validator/BUILD.bazel

@@ -4,10 +4,10 @@ go_library(
     name = "go_default_library",
     srcs = [
         "aggregator.go",
-        "duties.go",
         "attester.go",
         "blocks.go",
         "construct_generic_block.go",
+        "duties.go",
         "exit.go",
         "log.go",
         "proposer.go",
@@ -179,10 +179,10 @@ go_test(
     timeout = "moderate",
     srcs = [
         "aggregator_test.go",
-        "duties_test.go",
         "attester_test.go",
         "blocks_test.go",
         "construct_generic_block_test.go",
+        "duties_test.go",
         "exit_test.go",
         "proposer_altair_test.go",
         "proposer_attestations_test.go",
@@ -201,6 +201,7 @@ go_test(
         "status_mainnet_test.go",
         "status_test.go",
         "sync_committee_test.go",
+        "unblinder_test.go",
         "validator_test.go",
     ],
     embed = [":go_default_library"],

beacon-chain/rpc/prysm/v1alpha1/validator/unblinder.go

@@ -13,15 +13,22 @@ import (
 )
 
 func unblindBlobsSidecars(block interfaces.SignedBeaconBlock, bundle *enginev1.BlobsBundle) ([]*ethpb.BlobSidecar, error) {
-	if block.Version() < version.Deneb || bundle == nil {
+	if block.Version() < version.Deneb {
 		return nil, nil
 	}
-	header, err := block.Header()
+	body := block.Block().Body()
+	blockCommitments, err := body.BlobKzgCommitments()
 	if err != nil {
 		return nil, err
 	}
-	body := block.Block().Body()
-	blockCommitments, err := body.BlobKzgCommitments()
+	if len(blockCommitments) == 0 {
+		return nil, nil
+	}
+	// Do not allow builders to provide no blob bundles for blocks which carry commitments.
+	if bundle == nil {
+		return nil, errors.New("no valid bundle provided")
+	}
+	header, err := block.Header()
 	if err != nil {
 		return nil, err
 	}

beacon-chain/rpc/prysm/v1alpha1/validator/unblinder_test.go

@@ -0,0 +1,34 @@
+package validator
+
+import (
+	"testing"
+
+	consensusblocks "github.com/prysmaticlabs/prysm/v5/consensus-types/blocks"
+	ethpb "github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v5/testing/assert"
+)
+
+func TestUnblinder_UnblindBlobSidecars_InvalidBundle(t *testing.T) {
+	wBlock, err := consensusblocks.NewSignedBeaconBlock(&ethpb.SignedBeaconBlockDeneb{
+		Block: &ethpb.BeaconBlockDeneb{
+			Body: &ethpb.BeaconBlockBodyDeneb{},
+		},
+		Signature: nil,
+	})
+	assert.NoError(t, err)
+	_, err = unblindBlobsSidecars(wBlock, nil)
+	assert.NoError(t, err)
+
+	wBlock, err = consensusblocks.NewSignedBeaconBlock(&ethpb.SignedBeaconBlockDeneb{
+		Block: &ethpb.BeaconBlockDeneb{
+			Body: &ethpb.BeaconBlockBodyDeneb{
+				BlobKzgCommitments: [][]byte{[]byte("a"), []byte("b")},
+			},
+		},
+		Signature: nil,
+	})
+	assert.NoError(t, err)
+	_, err = unblindBlobsSidecars(wBlock, nil)
+	assert.ErrorContains(t, "no valid bundle provided", err)
+
+}