[PATCH AUTOSEL 4.14 061/103] rtc: pl030: fix possible race condition

Sasha Levin
2019-11-08T11:44:48Z

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

[ Upstream commit c778ec85825dc895936940072aea9fe9037db684 ]

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-pl030.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/rtc/rtc-pl030.c b/drivers/rtc/rtc-pl030.c
index f85a1a93e669f..343bb6ed17839 100644
--- a/drivers/rtc/rtc-pl030.c
+++ b/drivers/rtc/rtc-pl030.c
@@ -112,6 +112,13 @@ static int pl030_probe(struct amba_device *dev, const struct amba_id *id)
goto err_rtc;
}

+ rtc->rtc = devm_rtc_allocate_device(&dev->dev);
+ if (IS_ERR(rtc->rtc)) {
+ ret = PTR_ERR(rtc->rtc);
+ goto err_rtc;
+ }
+
+ rtc->rtc->ops = &pl030_ops;
rtc->base = ioremap(dev->res.start, resource_size(&dev->res));
if (!rtc->base) {
ret = -ENOMEM;
@@ -128,12 +135,9 @@ static int pl030_probe(struct amba_device *dev, const struct amba_id *id)
if (ret)
goto err_irq;

- rtc->rtc = rtc_device_register("pl030", &dev->dev, &pl030_ops,
- THIS_MODULE);
- if (IS_ERR(rtc->rtc)) {
- ret = PTR_ERR(rtc->rtc);
+ ret = rtc_register_device(rtc->rtc);
+ if (ret)
goto err_reg;
- }

return 0;

@@ -154,7 +158,6 @@ static int pl030_remove(struct amba_device *dev)
writel(0, rtc->base + RTC_CR);

free_irq(dev->irq[0], rtc);
- rtc_device_unregister(rtc->rtc);
iounmap(rtc->base);
amba_release_regions(dev);

--
2.20.1