Reject unknown specific device identification objects

pymodbus/pdu/device.py

@@ -205,7 +205,7 @@ def __getitem__(self, key):
 
         :param key: The register to read
         """
-        return self.stat_data.setdefault(key, "")
+        return self.stat_data.get(key, "")
 
     def __str__(self):
         """Build a representation of the device.

pymodbus/pdu/mei_message.py

@@ -79,6 +79,10 @@ async def datastore_update(
             return ExceptionResponse(self.function_code, ExcCodes.ILLEGAL_VALUE)
 
         information = DeviceInformationFactory.get(_MCB, self.read_code, self.object_id)
+        if self.read_code == DeviceInformation.SPECIFIC and (
+            0x07 <= self.object_id < 0x80 or not information.get(self.object_id)
+        ):
+            return ExceptionResponse(self.function_code, ExcCodes.ILLEGAL_ADDRESS)
         return ReadDeviceInformationResponse(
             read_code=self.read_code,
             information=information,

test/pdu/test_device.py

@@ -171,6 +171,7 @@ def test_modbus_device_identification_get(self):
         assert self.ident[0x08] != "x"
         assert self.ident[0x10] != "reserved"
         assert not self.ident[0x54]
+        assert 0x54 not in dict(self.ident)
 
     def test_modbus_device_identification_summary(self):
         """Test device identification summary creation."""

test/pdu/test_mei_messages.py

@@ -8,7 +8,7 @@
 
 import pytest
 
-from pymodbus.constants import DeviceInformation
+from pymodbus.constants import DeviceInformation, ExcCodes
 from pymodbus.pdu.device import ModbusControlBlock
 from pymodbus.pdu.mei_message import (
     ReadDeviceInformationRequest,
@@ -60,6 +60,14 @@ async def test_read_device_information_request(self, mock_server_context):
         with pytest.raises(KeyError):
             _ = result.information[0x81]
 
+        handle = ReadDeviceInformationRequest(
+            read_code=DeviceInformation.SPECIFIC, object_id=0x00
+        )
+        result = await handle.datastore_update(context, 0)
+        assert cast(ReadDeviceInformationResponse, result).information == {
+            0x00: "Company"
+        }
+
         handle = ReadDeviceInformationRequest(
             read_code=DeviceInformation.EXTENDED, object_id=0x80
         )
@@ -81,6 +89,17 @@ async def test_read_device_information_request_error(self, mock_server_context):
         assert (await handle.datastore_update(context, 0)).function_code == 0xAB
         handle.object_id = 0x100
         assert (await handle.datastore_update(context, 0)).function_code == 0xAB
+        handle = ReadDeviceInformationRequest(
+            read_code=DeviceInformation.SPECIFIC, object_id=0x54
+        )
+        result = await handle.datastore_update(context, 0)
+        assert result.exception_code == ExcCodes.ILLEGAL_ADDRESS
+        ModbusControlBlock().Identity[0xFE] = ""
+        handle = ReadDeviceInformationRequest(
+            read_code=DeviceInformation.SPECIFIC, object_id=0xFE
+        )
+        result = await handle.datastore_update(context, 0)
+        assert result.exception_code == ExcCodes.ILLEGAL_ADDRESS
 
     def test_read_device_information_calc1(self):
         """Test calculateRtuFrameSize, short buffer."""