rtc: rk808: fix possible race condition
[ Upstream commit 201fac95e7
]
The probe function is not allowed to fail after registering the RTC 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* */
Switch to devm_rtc_allocate_device/rtc_register_device to register the rtc
as late as possible.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pull/10/head
parent
6c1c171164
commit
6266010c38
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@ -416,12 +416,11 @@ static int rk808_rtc_probe(struct platform_device *pdev)
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device_init_wakeup(&pdev->dev, 1);
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rk808_rtc->rtc = devm_rtc_device_register(&pdev->dev, "rk808-rtc",
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&rk808_rtc_ops, THIS_MODULE);
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if (IS_ERR(rk808_rtc->rtc)) {
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ret = PTR_ERR(rk808_rtc->rtc);
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return ret;
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}
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rk808_rtc->rtc = devm_rtc_allocate_device(&pdev->dev);
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if (IS_ERR(rk808_rtc->rtc))
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return PTR_ERR(rk808_rtc->rtc);
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rk808_rtc->rtc->ops = &rk808_rtc_ops;
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rk808_rtc->irq = platform_get_irq(pdev, 0);
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if (rk808_rtc->irq < 0) {
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@ -438,9 +437,10 @@ static int rk808_rtc_probe(struct platform_device *pdev)
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if (ret) {
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dev_err(&pdev->dev, "Failed to request alarm IRQ %d: %d\n",
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rk808_rtc->irq, ret);
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return ret;
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}
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return ret;
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return rtc_register_device(rk808_rtc->rtc);
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}
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static struct platform_driver rk808_rtc_driver = {
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