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rtc: tps6586x: fix possible race condition

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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: Alexandre Belloni <alexandre.belloni@bootlin.com>
This commit is contained in:
Alexandre Belloni 2018-05-17 22:48:17 +02:00
parent 30d7891ae9
commit 63d2206307
1 changed files with 11 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
drivers/rtc/rtc-tps6586x.c
View File

@ -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: