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authorAlexandre Belloni <alexandre.belloni@bootlin.com>2018-05-17 23:20:39 +0300
committerAlexandre Belloni <alexandre.belloni@bootlin.com>2018-05-17 23:23:23 +0300
commit8bde032b280605c21a247557de9ee71e5835cab8 (patch)
treee3d739851951eea074ec52f54f4d3988eaeb8a47 /drivers/rtc/rtc-ab-b5ze-s3.c
parent02f3712f1f6c878c0fc4657d763272970b1013f5 (diff)
downloadlinux-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.c19
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);