prevent OR on bitlists of different length (#4209)

* prevent OR on bitlists of different length
* prevent OR on bitlists of different length

proto/beacon/db/attestation_container_helper.go

@@ -28,6 +28,9 @@ func NewContainerFromAttestations(atts []*ethpb.Attestation) *AttestationContain
 func (ac *AttestationContainer) Contains(att *ethpb.Attestation) bool {
 	all := bitfield.NewBitlist(att.AggregationBits.Len())
 	for _, sp := range ac.SignaturePairs {
+		if all.Len() != sp.AggregationBits.Len() {
+			continue
+		}
 		all = all.Or(sp.AggregationBits)
 	}
 	return all.Contains(att.AggregationBits)

proto/beacon/db/attestation_container_helper_test.go

@@ -63,6 +63,16 @@ func TestAttestationContainer_Contains(t *testing.T) {
 			contains: bitfield.Bitlist{0b01000000, 0b1},
 			want:     false,
 		},
+		{
+			input: []bitfield.Bitlist{
+				{0b10000001, 0b1},
+				{0b10000010, 0b1},
+				{0b10000100, 0b1},
+				{0b10010001, 0b1},
+			},
+			contains: bitfield.Bitlist{0b10000000, 0b10}, // Different length.
+			want:     false,
+		},
 	}
 	for i, tt := range tests {
 		t.Run(fmt.Sprintf("case_%d", i), func(t *testing.T) {