Bluetooth: btrtl: Prevent potential NULL dereference

The btrtl_initialize() function checks that rtl_load_file() either
had an error or it loaded a zero length file.  However, if it loaded
a zero length file then the error code is not set correctly.  It
results in an error pointer vs NULL bug, followed by a NULL pointer
dereference.  This was detected by Smatch:

drivers/bluetooth/btrtl.c:592 btrtl_initialize() warn: passing zero to 'ERR_PTR'

Fixes: 26503ad ("Bluetooth: btrtl: split the device initialization into smaller parts")
Signed-off-by: Dan Carpenter <[email protected]>
Reviewed-by: Hans de Goede <[email protected]>
Signed-off-by: Luiz Augusto von Dentz <[email protected]>

Author: Dan Carpenter

drivers/bluetooth/btrtl.c

@@ -1215,6 +1215,8 @@ struct btrtl_device_info *btrtl_initialize(struct hci_dev *hdev,
 			rtl_dev_err(hdev, "mandatory config file %s not found",
 				    btrtl_dev->ic_info->cfg_name);
 			ret = btrtl_dev->cfg_len;
+			if (!ret)
+				ret = -EINVAL;
 			goto err_free;
 		}
 	}