rtc: vr41xx: fix possible race condition
[ Upstream commit 9a99247c9c
]
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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pull/10/head
parent
aca6728fa1
commit
8f5e7596fe
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@ -292,13 +292,14 @@ static int rtc_probe(struct platform_device *pdev)
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goto err_rtc1_iounmap;
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}
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rtc = devm_rtc_device_register(&pdev->dev, rtc_name, &vr41xx_rtc_ops,
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THIS_MODULE);
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rtc = devm_rtc_allocate_device(&pdev->dev);
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if (IS_ERR(rtc)) {
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retval = PTR_ERR(rtc);
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goto err_iounmap_all;
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}
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rtc->ops = &vr41xx_rtc_ops;
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rtc->max_user_freq = MAX_PERIODIC_RATE;
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spin_lock_irq(&rtc_lock);
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@ -340,6 +341,10 @@ static int rtc_probe(struct platform_device *pdev)
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dev_info(&pdev->dev, "Real Time Clock of NEC VR4100 series\n");
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retval = rtc_register_device(rtc);
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if (retval)
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goto err_iounmap_all;
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return 0;
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err_iounmap_all:
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