[bug report] mei: fix error flow in probe

[bug report] mei: fix error flow in probe

[Dan Carpenter]

Hello Alexander Usyskin,

Commit 1ebc180d2b90 ("mei: fix error flow in probe") from Nov 2, 2025
(linux-next), leads to the following Smatch static checker warning:

	drivers/misc/mei/platform-vsc.c:384 mei_vsc_probe()
	error: potential zalloc NULL dereference: 'mei_dev->cdev'

drivers/misc/mei/platform-vsc.c
    334 static int mei_vsc_probe(struct platform_device *pdev)
    335 {
    336         struct device *dev = &pdev->dev;
    337         struct mei_device *mei_dev;
    338         struct mei_vsc_hw *hw;
    339         struct vsc_tp *tp;
    340         int ret;
    341 
    342         tp = *(struct vsc_tp **)dev_get_platdata(dev);
    343         if (!tp)
    344                 return dev_err_probe(dev, -ENODEV, "no platform data\n");
    345 
    346         mei_dev = kzalloc(size_add(sizeof(*mei_dev), sizeof(*hw)), GFP_KERNEL);
    347         if (!mei_dev)
    348                 return -ENOMEM;
    349 
    350         mei_device_init(mei_dev, dev, false, &mei_vsc_hw_ops);
    351 
    352         mei_dev->fw_f_fw_ver_supported = 0;
    353         mei_dev->kind = MEI_DEV_KIND_IVSC;
    354 
    355         hw = mei_dev_to_vsc_hw(mei_dev);
    356         atomic_set(&hw->write_lock_cnt, 0);
    357         hw->tp = tp;
    358 
    359         platform_set_drvdata(pdev, mei_dev);
    360 
    361         vsc_tp_register_event_cb(tp, mei_vsc_event_cb, mei_dev);
    362 
    363         ret = mei_register(mei_dev, dev);

If mei_register() fails to allocate mei_dev->cdev

    364         if (ret)
    365                 goto err;
    366 
    367         ret = mei_start(mei_dev);
    368         if (ret) {
    369                 dev_err_probe(dev, ret, "init hw failed\n");
    370                 goto err;
    371         }
    372 
    373         pm_runtime_enable(mei_dev->parent);
    374 
    375         return 0;
    376 
    377 err:
    378         mei_cancel_work(mei_dev);
    379 
    380         vsc_tp_register_event_cb(tp, NULL, NULL);
    381 
    382         mei_disable_interrupts(mei_dev);
    383 
--> 384         mei_deregister(mei_dev);

Then it leads to a crash here.

    385 
    386         return ret;
    387 }

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regards,
dan carpenter