[PATCH 1/3] rtc: mt6397: fix possible race condition

[PATCH 1/3] rtc: mt6397: fix possible race condition

[Alexandre Belloni]

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.

Cc: Eddie Huang <eddie.huang@mediatek.com>
Cc: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 drivers/rtc/rtc-mt6397.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/rtc/rtc-mt6397.c b/drivers/rtc/rtc-mt6397.c
index 385f8303bb41..e9a25ec4d434 100644
--- a/drivers/rtc/rtc-mt6397.c
+++ b/drivers/rtc/rtc-mt6397.c
@@ -332,6 +332,10 @@ static int mtk_rtc_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, rtc);
 
+	rtc->rtc_dev = devm_rtc_allocate_device(rtc->dev);
+	if (IS_ERR(rtc->rtc_dev))
+		return PTR_ERR(rtc->rtc_dev);
+
 	ret = request_threaded_irq(rtc->irq, NULL,
 				   mtk_rtc_irq_handler_thread,
 				   IRQF_ONESHOT | IRQF_TRIGGER_HIGH,
@@ -344,11 +348,11 @@ static int mtk_rtc_probe(struct platform_device *pdev)
 
 	device_init_wakeup(&pdev->dev, 1);
 
-	rtc->rtc_dev = rtc_device_register("mt6397-rtc", &pdev->dev,
-					   &mtk_rtc_ops, THIS_MODULE);
-	if (IS_ERR(rtc->rtc_dev)) {
+	rtc->rtc_dev->ops = &mtk_rtc_ops;
+
+	ret = rtc_register_device(rtc->rtc_dev);
+	if (ret) {
 		dev_err(&pdev->dev, "register rtc device failed\n");
-		ret = PTR_ERR(rtc->rtc_dev);
 		goto out_free_irq;
 	}
 
@@ -365,7 +369,6 @@ static int mtk_rtc_remove(struct platform_device *pdev)
 {
 	struct mt6397_rtc *rtc = platform_get_drvdata(pdev);
 
-	rtc_device_unregister(rtc->rtc_dev);
 	free_irq(rtc->irq, rtc->rtc_dev);
 	irq_dispose_mapping(rtc->irq);
 
-- 
2.19.0.rc2

[PATCH 2/3] rtc: pl030: fix possible race condition

[Alexandre Belloni]

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-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 f85a1a93e669..343bb6ed1783 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);
 
-- 
2.19.0.rc2

[PATCH 3/3] rtc: pl031: switch to devm_rtc_allocate_device/rtc_register_device

[Alexandre Belloni]

Switch to devm_rtc_allocate_device to simplify the erro and driver removal
paths.

Cc: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 drivers/rtc/rtc-pl031.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/rtc/rtc-pl031.c b/drivers/rtc/rtc-pl031.c
index 82eb7da2c478..30943d200c5e 100644
--- a/drivers/rtc/rtc-pl031.c
+++ b/drivers/rtc/rtc-pl031.c
@@ -310,7 +310,6 @@ static int pl031_remove(struct amba_device *adev)
 	device_init_wakeup(&adev->dev, false);
 	if (adev->irq[0])
 		free_irq(adev->irq[0], ldata);
-	rtc_device_unregister(ldata->rtc);
 	amba_release_regions(adev);
 
 	return 0;
@@ -383,24 +382,25 @@ static int pl031_probe(struct amba_device *adev, const struct amba_id *id)
 	}
 
 	device_init_wakeup(&adev->dev, true);
-	ldata->rtc = rtc_device_register("pl031", &adev->dev, ops,
-					THIS_MODULE);
-	if (IS_ERR(ldata->rtc)) {
-		ret = PTR_ERR(ldata->rtc);
+	ldata->rtc = devm_rtc_allocate_device(&adev->dev);
+	if (IS_ERR(ldata->rtc))
+		return PTR_ERR(ldata->rtc);
+
+	ldata->rtc->ops = ops;
+
+	ret = rtc_register_device(ldata->rtc);
+	if (ret)
 		goto out;
-	}
 
 	if (adev->irq[0]) {
 		ret = request_irq(adev->irq[0], pl031_interrupt,
 				  vendor->irqflags, "rtc-pl031", ldata);
 		if (ret)
-			goto out_no_irq;
+			goto out;
 		dev_pm_set_wake_irq(&adev->dev, adev->irq[0]);
 	}
 	return 0;
 
-out_no_irq:
-	rtc_device_unregister(ldata->rtc);
 out:
 	amba_release_regions(adev);
 err_req:
-- 
2.19.0.rc2

Re: [PATCH 3/3] rtc: pl031: switch to devm_rtc_allocate_device/rtc_register_device

[Linus Walleij]

On Sun, Sep 9, 2018 at 10:38 PM Alexandre Belloni
<alexandre.belloni@bootlin.com> wrote:

> Switch to devm_rtc_allocate_device to simplify the erro and driver removal
> paths.
>
> Cc: Linus Walleij <linus.walleij@linaro.org>
> Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Acked-by: Linus Walleij <linus.walleij@linaro.org>

Yours,
Linus Walleij

Re: [PATCH 1/3] rtc: mt6397: fix possible race condition

[Eddie Huang]

On Sun, 2018-09-09 at 22:38 +0200, Alexandre Belloni wrote:
> 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.
> 
> Cc: Eddie Huang <eddie.huang@mediatek.com>
> Cc: Sean Wang <sean.wang@mediatek.com>
> Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
> ---
>  drivers/rtc/rtc-mt6397.c | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/rtc/rtc-mt6397.c b/drivers/rtc/rtc-mt6397.c
> index 385f8303bb41..e9a25ec4d434 100644
> --- a/drivers/rtc/rtc-mt6397.c
> +++ b/drivers/rtc/rtc-mt6397.c
> @@ -332,6 +332,10 @@ static int mtk_rtc_probe(struct platform_device *pdev)
>  
>  	platform_set_drvdata(pdev, rtc);
>  
> +	rtc->rtc_dev = devm_rtc_allocate_device(rtc->dev);
> +	if (IS_ERR(rtc->rtc_dev))
> +		return PTR_ERR(rtc->rtc_dev);
> +
>  	ret = request_threaded_irq(rtc->irq, NULL,
>  				   mtk_rtc_irq_handler_thread,
>  				   IRQF_ONESHOT | IRQF_TRIGGER_HIGH,
> @@ -344,11 +348,11 @@ static int mtk_rtc_probe(struct platform_device *pdev)
>  
>  	device_init_wakeup(&pdev->dev, 1);
>  
> -	rtc->rtc_dev = rtc_device_register("mt6397-rtc", &pdev->dev,
> -					   &mtk_rtc_ops, THIS_MODULE);
> -	if (IS_ERR(rtc->rtc_dev)) {
> +	rtc->rtc_dev->ops = &mtk_rtc_ops;
> +
> +	ret = rtc_register_device(rtc->rtc_dev);
> +	if (ret) {
>  		dev_err(&pdev->dev, "register rtc device failed\n");
> -		ret = PTR_ERR(rtc->rtc_dev);
>  		goto out_free_irq;
>  	}
>  
> @@ -365,7 +369,6 @@ static int mtk_rtc_remove(struct platform_device *pdev)
>  {
>  	struct mt6397_rtc *rtc = platform_get_drvdata(pdev);
>  
> -	rtc_device_unregister(rtc->rtc_dev);
>  	free_irq(rtc->irq, rtc->rtc_dev);
>  	irq_dispose_mapping(rtc->irq);
>  

Thanks

Acked-by: Eddie Huang <eddie.huang@mediatek.com>