rtc: snvs: fix possible race condition

[ Upstream commit 6fd4fe9b496d9ba3382992ff4fde3871d1b6f63d ]

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 before requesting
the RTC IRQ using devm_rtc_allocate_device, and use rtc_register_device
to register the RTC device.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Dong Aisheng <aisheng.dong@nxp.com>
Link: https://lore.kernel.org/r/20190716071858.36750-1-Anson.Huang@nxp.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/rtc/rtc-snvs.c b/drivers/rtc/rtc-snvs.c
index 7ee673a25fd0a10f72213e8aec6d787b322b114a..4f9a107a04277fe2ce926be590b02141e93c0385 100644 (file)
--- 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)) {
@@ -343,10 +347,9 @@ 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);
+       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;
        }