AP_Compass: cope with NULL dev pointer in driver probe functions

libraries/AP_Compass/AP_Compass_AK8963.cpp

@@ -69,6 +69,9 @@ AP_Compass_Backend *AP_Compass_AK8963::probe(Compass &compass,
                                              AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
                                              enum Rotation rotation)
 {
+    if (!dev) {
+        return nullptr;
+    }
     AP_AK8963_BusDriver *bus = new AP_AK8963_BusDriver_HALDevice(std::move(dev));
     if (!bus) {
         return nullptr;
@@ -87,6 +90,9 @@ AP_Compass_Backend *AP_Compass_AK8963::probe_mpu9250(Compass &compass,
                                                      AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
                                                      enum Rotation rotation)
 {
+    if (!dev) {
+        return nullptr;
+    }
     AP_InertialSensor &ins = *AP_InertialSensor::get_instance();
 
     /* Allow MPU9250 to shortcut auxiliary bus and host bus */

libraries/AP_Compass/AP_Compass_BMM150.cpp

@@ -65,6 +65,9 @@ extern const AP_HAL::HAL &hal;
 AP_Compass_Backend *AP_Compass_BMM150::probe(Compass &compass,
                                              AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev)
 {
+    if (!dev) {
+        return nullptr;
+    }
     AP_Compass_BMM150 *sensor = new AP_Compass_BMM150(compass, std::move(dev));
     if (!sensor || !sensor->init()) {
         delete sensor;

libraries/AP_Compass/AP_Compass_HMC5843.cpp

@@ -113,6 +113,9 @@ AP_Compass_Backend *AP_Compass_HMC5843::probe(Compass &compass,
                                               bool force_external,
                                               enum Rotation rotation)
 {
+    if (!dev) {
+        return nullptr;
+    }
     AP_HMC5843_BusDriver *bus = new AP_HMC5843_BusDriver_HALDevice(std::move(dev));
     if (!bus) {
         return nullptr;

libraries/AP_Compass/AP_Compass_LSM303D.cpp

@@ -162,6 +162,9 @@ AP_Compass_LSM303D::AP_Compass_LSM303D(Compass &compass, AP_HAL::OwnPtr<AP_HAL::
 AP_Compass_Backend *AP_Compass_LSM303D::probe(Compass &compass,
                                               AP_HAL::OwnPtr<AP_HAL::Device> dev)
 {
+    if (!dev) {
+        return nullptr;
+    }
     AP_Compass_LSM303D *sensor = new AP_Compass_LSM303D(compass, std::move(dev));
     if (!sensor || !sensor->init()) {
         delete sensor;

libraries/AP_Compass/AP_Compass_LSM9DS1.cpp

@@ -60,6 +60,9 @@ extern const AP_HAL::HAL &hal;
 AP_Compass_Backend *AP_Compass_LSM9DS1::probe(Compass &compass,
                                               AP_HAL::OwnPtr<AP_HAL::Device> dev)
 {
+    if (!dev) {
+        return nullptr;
+    }
     AP_Compass_LSM9DS1 *sensor = new AP_Compass_LSM9DS1(compass, std::move(dev));
     if (!sensor || !sensor->init()) {
         delete sensor;