[bug report] net: wwan: t7xx: Add control port

[Dan Carpenter]

Hello Haijun Liu,

The patch da45d2566a1d: "net: wwan: t7xx: Add control port" from May
6, 2022, leads to the following Smatch static checker warning:

	drivers/net/wwan/t7xx/t7xx_modem_ops.c:499 t7xx_core_hk_handler()
	error: potentially dereferencing uninitialized 'event'.

drivers/net/wwan/t7xx/t7xx_modem_ops.c
    457 static void t7xx_core_hk_handler(struct t7xx_modem *md, struct t7xx_fsm_ctl *ctl,
    458                                  enum t7xx_fsm_event_state event_id,
    459                                  enum t7xx_fsm_event_state err_detect)
    460 {
    461         struct t7xx_sys_info *core_info = &md->core_md;
    462         struct device *dev = &md->t7xx_dev->pdev->dev;
    463         struct t7xx_fsm_event *event, *event_next;
                                       ^^^^^


    464         unsigned long flags;
    465         int ret;
    466 
    467         t7xx_prepare_host_rt_data_query(core_info);
    468 
    469         while (!kthread_should_stop()) {
                        ^^^^^^^^^^^^^^^^^^^^^
What about this is true on the first iteration through the loop?

    470                 bool event_received = false;
    471 
    472                 spin_lock_irqsave(&ctl->event_lock, flags);
    473                 list_for_each_entry_safe(event, event_next, &ctl->event_queue, entry) {
    474                         if (event->event_id == err_detect) {
    475                                 list_del(&event->entry);
    476                                 spin_unlock_irqrestore(&ctl->event_lock, flags);
    477                                 dev_err(dev, "Core handshake error event received\n");
    478                                 goto err_free_event;
    479                         } else if (event->event_id == event_id) {
    480                                 list_del(&event->entry);
    481                                 event_received = true;
    482                                 break;
    483                         }
    484                 }
    485                 spin_unlock_irqrestore(&ctl->event_lock, flags);
    486 
    487                 if (event_received)
    488                         break;
    489 
    490                 wait_event_interruptible(ctl->event_wq, !list_empty(&ctl->event_queue) ||
    491                                          kthread_should_stop());
    492                 if (kthread_should_stop())
    493                         goto err_free_event;
    494         }
    495 
    496         if (ctl->exp_flg)
    497                 goto err_free_event;
                        ^^^^^^^^^^^^^^^^^^^
Uninitialized on this path too.

    498 
--> 499         ret = t7xx_parse_host_rt_data(ctl, core_info, dev, event->data, event->length);
                                                                   ^^^^^^^
Uninitialized?

    500         if (ret) {
    501                 dev_err(dev, "Host failure parsing runtime data: %d\n", ret);
    502                 goto err_free_event;
    503         }
    504 
    505         if (ctl->exp_flg)
    506                 goto err_free_event;
    507 
    508         ret = t7xx_prepare_device_rt_data(core_info, dev, event->data);
    509         if (ret) {
    510                 dev_err(dev, "Device failure parsing runtime data: %d", ret);
    511                 goto err_free_event;
    512         }
    513 
    514         core_info->ready = true;
    515         core_info->handshake_ongoing = false;
    516         wake_up(&ctl->async_hk_wq);
    517 err_free_event:
    518         kfree(event);
    519 }

regards,
dan carpenter