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Subject[PATCH 1/2] rtc: st-lpc: fix possible race condition
Date
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.

Switch to devm_rtc_allocate_device/rtc_register_device to allocate the rtc
before requesting the IRQ.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
drivers/rtc/rtc-st-lpc.c | 24 +++++++++---------------
1 file changed, 9 insertions(+), 15 deletions(-)

diff --git a/drivers/rtc/rtc-st-lpc.c b/drivers/rtc/rtc-st-lpc.c
index d5222667f892..2f1ef2c28740 100644
--- a/drivers/rtc/rtc-st-lpc.c
+++ b/drivers/rtc/rtc-st-lpc.c
@@ -212,6 +212,10 @@ static int st_rtc_probe(struct platform_device *pdev)
if (!rtc)
return -ENOMEM;

+ rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
+ if (IS_ERR(rtc->rtc_dev))
+ return PTR_ERR(rtc->rtc_dev);
+
spin_lock_init(&rtc->lock);

res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
@@ -253,26 +257,17 @@ static int st_rtc_probe(struct platform_device *pdev)

platform_set_drvdata(pdev, rtc);

- rtc->rtc_dev = rtc_device_register("st-lpc-rtc", &pdev->dev,
- &st_rtc_ops, THIS_MODULE);
- if (IS_ERR(rtc->rtc_dev)) {
+ rtc->rtc_dev->ops = &st_rtc_ops;
+
+ ret = rtc_register_device(rtc->rtc_dev);
+ if (ret) {
clk_disable_unprepare(rtc->clk);
- return PTR_ERR(rtc->rtc_dev);
+ return ret;
}

return 0;
}

-static int st_rtc_remove(struct platform_device *pdev)
-{
- struct st_rtc *rtc = platform_get_drvdata(pdev);
-
- if (likely(rtc->rtc_dev))
- rtc_device_unregister(rtc->rtc_dev);
-
- return 0;
-}
-
#ifdef CONFIG_PM_SLEEP
static int st_rtc_suspend(struct device *dev)
{
@@ -325,7 +320,6 @@ static struct platform_driver st_rtc_platform_driver = {
.of_match_table = st_rtc_match,
},
.probe = st_rtc_probe,
- .remove = st_rtc_remove,
};

module_platform_driver(st_rtc_platform_driver);
--
2.17.0
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