Fix: GetDevlinkDeviceParam to handle edge-cases correctly

On some kernels GetDevlinkDeviceParam may return empty values
for some kernel parameters. The netlink library is able to handle this, but
the code in GetDevlinkDeviceParam function may panic if unexpected value
received. Add extra checks to avoid panics

Author: ykulazhenkov

pkg/host/internal/network/network.go

@@ -264,12 +264,12 @@ func (n *network) GetDevlinkDeviceParam(pciAddr, paramName string) (string, erro
 		funcLog.Error(err, "GetDevlinkDeviceParam(): fail to get devlink device param")
 		return "", err
 	}
-	if len(param.Values) == 0 {
-		err = fmt.Errorf("param %s has no value", paramName)
-		funcLog.Error(err, "GetDevlinkDeviceParam(): error")
-		return "", err
+	if len(param.Values) == 0 || param.Values[0].Data == nil {
+		funcLog.Info("GetDevlinkDeviceParam(): WARNING: can't read devlink parameter from the device, an empty value received")
+		return "", nil
 	}
 	var value string
+	var ok bool
 	switch param.Type {
 	case nl.DEVLINK_PARAM_TYPE_U8, nl.DEVLINK_PARAM_TYPE_U16, nl.DEVLINK_PARAM_TYPE_U32:
 		var valData uint64
@@ -281,14 +281,22 @@ func (n *network) GetDevlinkDeviceParam(pciAddr, paramName string) (string, erro
 		case uint32:
 			valData = uint64(v)
 		default:
-			return "", fmt.Errorf("unexpected uint type type")
+			return "", fmt.Errorf("value is not uint")
 		}
 		value = strconv.FormatUint(valData, 10)
 
 	case nl.DEVLINK_PARAM_TYPE_STRING:
-		value = param.Values[0].Data.(string)
+		value, ok = param.Values[0].Data.(string)
+		if !ok {
+			return "", fmt.Errorf("value is not a string")
+		}
 	case nl.DEVLINK_PARAM_TYPE_BOOL:
-		value = strconv.FormatBool(param.Values[0].Data.(bool))
+		var boolValue bool
+		boolValue, ok = param.Values[0].Data.(bool)
+		if !ok {
+			return "", fmt.Errorf("value is not a bool")
+		}
+		value = strconv.FormatBool(boolValue)
 	default:
 		return "", fmt.Errorf("unknown value type: %d", param.Type)
 	}

pkg/host/internal/sriov/sriov.go

@@ -376,6 +376,11 @@ func (s *sriov) configureHWOptionsForSwitchdev(iface *sriovnetworkv1.Interface)
 		log.Log.Error(err, "configureHWOptionsForSwitchdev(): fail to read current flow steering mode for the device", "device", iface.PciAddress)
 		return err
 	}
+	if currentFlowSteeringMode == "" {
+		log.Log.V(2).Info("configureHWOptionsForSwitchdev(): can't detect current flow_steering_mode mode for the device, skip",
+			"device", iface.PciAddress)
+		return nil
+	}
 	if currentFlowSteeringMode == desiredFlowSteeringMode {
 		return nil
 	}