[PATCH AUTOSEL 4.14 05/30] rtc: 88pm860x: fix possible race condition

Sasha Levin
2020-04-15T12:10:25Z

From: Alexandre Belloni <alexandre.belloni@bootlin.com>

[ 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>
---
drivers/rtc/rtc-88pm860x.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/rtc/rtc-88pm860x.c b/drivers/rtc/rtc-88pm860x.c
index 7d3e5168fcefc..efbbde7379f13 100644
--- a/drivers/rtc/rtc-88pm860x.c
+++ b/drivers/rtc/rtc-88pm860x.c
@@ -341,6 +341,10 @@ 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);
@@ -382,13 +386,11 @@ 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
--
2.20.1