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Commit 63d22063 authored by Alexandre Belloni's avatar Alexandre Belloni
Browse files

rtc: tps6586x: fix possible race condition 



The probe function is not allowed to fail after the RTC is registered
because the following may happen:

CPU0:                                CPU1:
sys_load_module()
 do_init_module()
  do_one_initcall()
   cmos_do_probe()
    rtc_device_register()
     __register_chrdev()
     cdev->owner = struct module*
                                     open("/dev/rtc0")
    rtc_device_unregister()
  module_put()
  free_module()
   module_free(mod->module_core)
   /* struct module *module is now
      freed */
                                      chrdev_open()
                                       spin_lock(cdev_lock)
                                       cdev_get()
                                        try_module_get()
                                         module_is_live()
                                         /* dereferences already
                                            freed struct module* */

Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@bootlin.com>
parent 30d7891a

drivers/rtc/rtc-tps6586x.c

+11 −3
Original line number Diff line number Diff line
@@ -276,14 +276,15 @@ static int tps6586x_rtc_probe(struct platform_device *pdev) 
	device_init_wakeup(&pdev->dev, 1);



	platform_set_drvdata(pdev, rtc);

	rtc->rtc = devm_rtc_device_register(&pdev->dev, dev_name(&pdev->dev),

				       &tps6586x_rtc_ops, THIS_MODULE);

	rtc->rtc = devm_rtc_allocate_device(&pdev->dev);

	if (IS_ERR(rtc->rtc)) {

		ret = PTR_ERR(rtc->rtc);

		dev_err(&pdev->dev, "RTC device register: ret %d\n", ret);

		dev_err(&pdev->dev, "RTC allocate device: ret %d\n", ret);

		goto fail_rtc_register;

	}



	rtc->rtc->ops = &tps6586x_rtc_ops;



	ret = devm_request_threaded_irq(&pdev->dev, rtc->irq, NULL,

				tps6586x_rtc_irq,

				IRQF_ONESHOT,
@@ -294,6 +295,13 @@ static int tps6586x_rtc_probe(struct platform_device *pdev) 
		goto fail_rtc_register;

	}

	disable_irq(rtc->irq);



	ret = rtc_register_device(rtc->rtc);

	if (ret) {

		dev_err(&pdev->dev, "RTC device register: ret %d\n", ret);

		goto fail_rtc_register;

	}



	return 0;



fail_rtc_register: