mcb: fix error handling in mcb_alloc_bus()

There are two bugs:
1) If ida_simple_get() fails then this code calls put_device(carrier)
but we haven't yet called get_device(carrier) and probably that
leads to a use after free.
2) After device_initialize() then we need to use put_device() to
release the bus. This will free the internal resources tied to the
device and call mcb_free_bus() which will free the rest.

Fixes: 5d9e2ab9fea4 ("mcb: Implement bus->dev.release callback")
Fixes: 18d288198099 ("mcb: Correctly initialize the bus's device")
Cc: [e-mail]
Signed-off-by: Dan Carpenter <[e-mail]>
Signed-off-by: Johannes Thumshirn <[e-mail]>
Link: https://lore.kernel.org/r/32e160cf68[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/mcb/mcb-core.c

···
 
 	bus_nr = ida_simple_get(&mcb_ida, 0, 0, GFP_KERNEL);
 	if (bus_nr < 0) {
-		rc = bus_nr;
-		goto err_free;
+		kfree(bus);
+		return ERR_PTR(bus_nr);
 	}
 
 	bus->bus_nr = bus_nr;
···
 	dev_set_name(&bus->dev, "mcb:%d", bus_nr);
 	rc = device_add(&bus->dev);
 	if (rc)
-		goto err_free;
+		goto err_put;
 
 	return bus;
-err_free:
-	put_device(carrier);
-	kfree(bus);
+
+err_put:
+	put_device(&bus->dev);
 	return ERR_PTR(rc);
 }
 EXPORT_SYMBOL_NS_GPL(mcb_alloc_bus, MCB);