[PATCH AUTOSEL 4.19 182/191] rtc: armada38x: fix possible race condition

Sasha Levin
2019-11-10T02:45:51Z

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

[ Upstream commit 7d61cbb945a753af08e247b5f10bdd5dbb8d6c80 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/rtc/rtc-armada38x.c | 22 +++++++++++-----------
1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/drivers/rtc/rtc-armada38x.c b/drivers/rtc/rtc-armada38x.c
index bde53c8ccee2c..b74338d6dde60 100644
--- a/drivers/rtc/rtc-armada38x.c
+++ b/drivers/rtc/rtc-armada38x.c
@@ -514,7 +514,6 @@ MODULE_DEVICE_TABLE(of, armada38x_rtc_of_match_table);

static __init int armada38x_rtc_probe(struct platform_device *pdev)
{
- const struct rtc_class_ops *ops;
struct resource *res;
struct armada38x_rtc *rtc;
const struct of_device_id *match;
@@ -551,6 +550,11 @@ static __init int armada38x_rtc_probe(struct platform_device *pdev)
dev_err(&pdev->dev, "no irq\n");
return rtc->irq;
}
+
+ rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
+ if (IS_ERR(rtc->rtc_dev))
+ return PTR_ERR(rtc->rtc_dev);
+
if (devm_request_irq(&pdev->dev, rtc->irq, armada38x_rtc_alarm_irq,
0, pdev->name, rtc) < 0) {
dev_warn(&pdev->dev, "Interrupt not available.\n");
@@ -560,28 +564,24 @@ static __init int armada38x_rtc_probe(struct platform_device *pdev)

if (rtc->irq != -1) {
device_init_wakeup(&pdev->dev, 1);
- ops = &armada38x_rtc_ops;
+ rtc->rtc_dev->ops = &armada38x_rtc_ops;
} else {
/*
* If there is no interrupt available then we can't
* use the alarm
*/
- ops = &armada38x_rtc_ops_noirq;
+ rtc->rtc_dev->ops = &armada38x_rtc_ops_noirq;
}
rtc->data = (struct armada38x_rtc_data *)match->data;

-
/* Update RTC-MBUS bridge timing parameters */
rtc->data->update_mbus_timing(rtc);

- rtc->rtc_dev = devm_rtc_device_register(&pdev->dev, pdev->name,
- ops, THIS_MODULE);
- if (IS_ERR(rtc->rtc_dev)) {
- ret = PTR_ERR(rtc->rtc_dev);
+ ret = rtc_register_device(rtc->rtc_dev);
+ if (ret)
dev_err(&pdev->dev, "Failed to register RTC device: %d\n", ret);
- return ret;
- }
- return 0;
+
+ return ret;
}

#ifdef CONFIG_PM_SLEEP
--
2.20.1