[PATCH V2] rtc: snvs: fix possible race condition

[Anson . Huang]

From: Anson Huang <anson.hu...@nxp.com>

The RTC IRQ is requested before the struct rtc_device is allocated,
this may lead to a NULL pointer dereference in IRQ handler.

To fix this issue, allocating the rtc_device struct and register rtc
device before requesting the RTC IRQ.

Using devm_rtc_allocate_device/rtc_register_device instead of
devm_rtc_device_register.

Signed-off-by: Anson Huang <anson.hu...@nxp.com>
---
Changes since V1:
        - move devm_request_irq() to after rtc device register done, make sure 
everything
          is ready before enabling IRQ.
---
 drivers/rtc/rtc-snvs.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/rtc/rtc-snvs.c b/drivers/rtc/rtc-snvs.c
index 7ee673a2..d9650e7 100644
--- a/drivers/rtc/rtc-snvs.c
+++ b/drivers/rtc/rtc-snvs.c
@@ -279,6 +279,10 @@ static int snvs_rtc_probe(struct platform_device *pdev)
        if (!data)
                return -ENOMEM;
 
+       data->rtc = devm_rtc_allocate_device(&pdev->dev);
+       if (IS_ERR(data->rtc))
+               return PTR_ERR(data->rtc);
+
        data->regmap = syscon_regmap_lookup_by_phandle(pdev->dev.of_node, 
"regmap");
 
        if (IS_ERR(data->regmap)) {
@@ -335,6 +339,13 @@ static int snvs_rtc_probe(struct platform_device *pdev)
        if (ret)
                dev_err(&pdev->dev, "failed to enable irq wake\n");
 
+       data->rtc->ops = &snvs_rtc_ops;
+       ret = rtc_register_device(data->rtc);
+       if (ret) {
+               dev_err(&pdev->dev, "failed to register rtc: %d\n", ret);
+               goto error_rtc_device_register;
+       }
+
        ret = devm_request_irq(&pdev->dev, data->irq, snvs_rtc_irq_handler,
                               IRQF_SHARED, "rtc alarm", &pdev->dev);
        if (ret) {
@@ -343,14 +354,6 @@ static int snvs_rtc_probe(struct platform_device *pdev)
                goto error_rtc_device_register;
        }
 
-       data->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
-                                       &snvs_rtc_ops, THIS_MODULE);
-       if (IS_ERR(data->rtc)) {
-               ret = PTR_ERR(data->rtc);
-               dev_err(&pdev->dev, "failed to register rtc: %d\n", ret);
-               goto error_rtc_device_register;
-       }
-
        return 0;
 
 error_rtc_device_register:
-- 
2.7.4