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| author | Alexandre Belloni <alexandre.belloni@bootlin.com> | 2018-05-17 23:20:39 +0300 |
|---|---|---|
| committer | Alexandre Belloni <alexandre.belloni@bootlin.com> | 2018-05-17 23:23:23 +0300 |
| commit | 8bde032b280605c21a247557de9ee71e5835cab8 (patch) | |
| tree | e3d739851951eea074ec52f54f4d3988eaeb8a47 /drivers/rtc/rtc-ab-b5ze-s3.c | |
| parent | 02f3712f1f6c878c0fc4657d763272970b1013f5 (diff) | |
| download | linux-8bde032b280605c21a247557de9ee71e5835cab8.tar.xz | |
rtc: ab-b5ze-s3: fix possible race conditions
The IRQ is requested before the struct rtc is allocated and registered, but
this struct is used in the IRQ handler. This may lead to a NULL pointer
dereference.
Also, 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* */
Switch to devm_rtc_allocate_device/rtc_register_device to allocate the rtc
before requesting the IRQ and register the RTC as late as possible.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Diffstat (limited to 'drivers/rtc/rtc-ab-b5ze-s3.c')
| -rw-r--r-- | drivers/rtc/rtc-ab-b5ze-s3.c | 19 |
1 files changed, 11 insertions, 8 deletions
diff --git a/drivers/rtc/rtc-ab-b5ze-s3.c b/drivers/rtc/rtc-ab-b5ze-s3.c index 8dc451932446..f486912577e7 100644 --- a/drivers/rtc/rtc-ab-b5ze-s3.c +++ b/drivers/rtc/rtc-ab-b5ze-s3.c @@ -925,6 +925,14 @@ static int abb5zes3_probe(struct i2c_client *client, if (ret) goto err; + data->rtc = devm_rtc_allocate_device(dev); + ret = PTR_ERR_OR_ZERO(data->rtc); + if (ret) { + dev_err(dev, "%s: unable to allocate RTC device (%d)\n", + __func__, ret); + goto err; + } + if (client->irq > 0) { ret = devm_request_threaded_irq(dev, client->irq, NULL, _abb5zes3_rtc_interrupt, @@ -942,14 +950,7 @@ static int abb5zes3_probe(struct i2c_client *client, } } - data->rtc = devm_rtc_device_register(dev, DRV_NAME, &rtc_ops, - THIS_MODULE); - ret = PTR_ERR_OR_ZERO(data->rtc); - if (ret) { - dev_err(dev, "%s: unable to register RTC device (%d)\n", - __func__, ret); - goto err; - } + data->rtc->ops = &rtc_ops; /* Enable battery low detection interrupt if battery not already low */ if (!data->battery_low && data->irq) { @@ -961,6 +962,8 @@ static int abb5zes3_probe(struct i2c_client *client, } } + ret = rtc_register_device(data->rtc); + err: if (ret && data && data->irq) device_init_wakeup(dev, false); |