[KGA-65] fix: decode legacy chain id overflow

cairo_zero/tests/src/utils/test_eth_transaction.py

@@ -28,6 +28,22 @@ async def test_should_raise_with_list_items(self, cairo_run):
             with cairo_error():
                 cairo_run("test__decode", data=list(encode(list(transaction.values()))))
 
+        async def test_should_raise_if_chain_id_overflow_legacy_transaction(
+            self, cairo_run
+        ):
+            transaction = {
+                "nonce": 0,
+                "gasPrice": 234567897654321,
+                "gas": 2_000_000,
+                "to": "0xF0109fC8DF283027b6285cc889F5aA624EaC1F55",
+                "value": 1_000_000_000,
+                "data": b"",
+                "chainId": 2**252,
+            }
+            with cairo_error(message="assert_nn(31 - items[6].data_len);"):
+                encoded_unsigned_tx = rlp_encode_signed_data(transaction)
+                cairo_run("test__decode", data=list(encoded_unsigned_tx))
+
         @given(value=st.integers(min_value=2**248))
         @pytest.mark.parametrize("transaction", TRANSACTIONS)
         @pytest.mark.parametrize(

cairo_zero/utils/eth_transaction.cairo

@@ -62,18 +62,23 @@ namespace EthTransaction {
 
         // pre eip-155 txs have 6 fields, post eip-155 txs have 9 fields
         if (items_len == 6) {
+            tempvar range_check_ptr = range_check_ptr;
             tempvar is_some = 0;
             tempvar chain_id = 0;
         } else {
             assert items_len = 9;
             assert items[6].is_list = FALSE;
             assert items[7].is_list = FALSE;
             assert items[8].is_list = FALSE;
+
+            assert_nn(31 - items[6].data_len);
             let chain_id = Helpers.bytes_to_felt(items[6].data_len, items[6].data);
 
+            tempvar range_check_ptr = range_check_ptr;
             tempvar is_some = 1;
             tempvar chain_id = chain_id;
         }
+        let range_check_ptr = [ap - 3];
         let is_some = [ap - 2];
         let chain_id = [ap - 1];