rtc: sunxi: fix possible race condition

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>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

diff --git a/drivers/rtc/rtc-sunxi.c b/drivers/rtc/rtc-sunxi.c
index dadbf8b324ad24366c1f38db5195de03ab344e42..21865d3d8fe8c025cca62cbda605cd9c2cb7331c 100644 (file)
--- a/drivers/rtc/rtc-sunxi.c
+++ b/drivers/rtc/rtc-sunxi.c
@@ -445,6 +445,10 @@ static int sunxi_rtc_probe(struct platform_device *pdev)
        platform_set_drvdata(pdev, chip);
        chip->dev = &pdev->dev;
 
+       chip->rtc = devm_rtc_allocate_device(&pdev->dev);
+       if (IS_ERR(chip->rtc))
+               return PTR_ERR(chip->rtc);
+
        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        chip->base = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(chip->base))
@@ -481,11 +485,12 @@ static int sunxi_rtc_probe(struct platform_device *pdev)
        writel(SUNXI_ALRM_IRQ_STA_CNT_IRQ_PEND, chip->base +
                        SUNXI_ALRM_IRQ_STA);
 
-       chip->rtc = rtc_device_register("rtc-sunxi", &pdev->dev,
-                       &sunxi_rtc_ops, THIS_MODULE);
-       if (IS_ERR(chip->rtc)) {
+       chip->rtc->ops = &sunxi_rtc_ops;
+
+       ret = rtc_register_device(chip->rtc);
+       if (ret) {
                dev_err(&pdev->dev, "unable to register device\n");
-               return PTR_ERR(chip->rtc);
+               return ret;
        }
 
        dev_info(&pdev->dev, "RTC enabled\n");
@@ -493,18 +498,8 @@ static int sunxi_rtc_probe(struct platform_device *pdev)
        return 0;
 }
 
-static int sunxi_rtc_remove(struct platform_device *pdev)
-{
-       struct sunxi_rtc_dev *chip = platform_get_drvdata(pdev);
-
-       rtc_device_unregister(chip->rtc);
-
-       return 0;
-}
-
 static struct platform_driver sunxi_rtc_driver = {
        .probe          = sunxi_rtc_probe,
-       .remove         = sunxi_rtc_remove,
        .driver         = {
                .name           = "sunxi-rtc",
                .of_match_table = sunxi_rtc_dt_ids,