rtc: 88pm860x: fix possible race condition

[ Upstream commit 9cf4789e6e4673d0b2c96fa6bb0c35e81b43111a ]

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

Also remove the unnecessary error message as the core already prints the
info.

Link: https://lore.kernel.org/r/20200311223956.51352-1-alexandre.belloni@bootlin.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/rtc/rtc-88pm860x.c b/drivers/rtc/rtc-88pm860x.c
index 4743b16..1526402 100644 (file)
--- a/drivers/rtc/rtc-88pm860x.c
+++ b/drivers/rtc/rtc-88pm860x.c
@@ -336,6 +336,10 @@ static int pm860x_rtc_probe(struct platform_device *pdev)
        info->dev = &pdev->dev;
        dev_set_drvdata(&pdev->dev, info);
 
+       info->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
+       if (IS_ERR(info->rtc_dev))
+               return PTR_ERR(info->rtc_dev);
+
        ret = devm_request_threaded_irq(&pdev->dev, info->irq, NULL,
                                        rtc_update_handler, IRQF_ONESHOT, "rtc",
                                        info);
@@ -377,13 +381,11 @@ static int pm860x_rtc_probe(struct platform_device *pdev)
                }
        }
 
-       info->rtc_dev = devm_rtc_device_register(&pdev->dev, "88pm860x-rtc",
-                                           &pm860x_rtc_ops, THIS_MODULE);
-       ret = PTR_ERR(info->rtc_dev);
-       if (IS_ERR(info->rtc_dev)) {
-               dev_err(&pdev->dev, "Failed to register RTC device: %d\n", ret);
+       info->rtc_dev->ops = &pm860x_rtc_ops;
+
+       ret = rtc_register_device(info->rtc_dev);
+       if (ret)
                return ret;
-       }
 
        /*
         * enable internal XO instead of internal 3.25MHz clock since it can