rtc: sh: 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
struct before requesting the IRQ.

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

diff --git a/drivers/rtc/rtc-sh.c b/drivers/rtc/rtc-sh.c
index 7fffe6d..d9e67ca 100644 (file)
--- a/drivers/rtc/rtc-sh.c
+++ b/drivers/rtc/rtc-sh.c
@@ -530,6 +530,10 @@ static int __init sh_rtc_probe(struct platform_device *pdev)
                rtc->clk = NULL;
        }
 
+       rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
+       if (IS_ERR(rtc->rtc_dev))
+               return PTR_ERR(rtc->rtc_dev);
+
        clk_enable(rtc->clk);
 
        rtc->capabilities = RTC_DEF_CAPABILITIES;
@@ -593,15 +597,13 @@ static int __init sh_rtc_probe(struct platform_device *pdev)
        sh_rtc_setaie(&pdev->dev, 0);
        sh_rtc_setcie(&pdev->dev, 0);
 
-       rtc->rtc_dev = devm_rtc_device_register(&pdev->dev, "sh",
-                                          &sh_rtc_ops, THIS_MODULE);
-       if (IS_ERR(rtc->rtc_dev)) {
-               ret = PTR_ERR(rtc->rtc_dev);
-               goto err_unmap;
-       }
-
+       rtc->rtc_dev->ops = &sh_rtc_ops;
        rtc->rtc_dev->max_user_freq = 256;
 
+       ret = rtc_register_device(rtc->rtc_dev);
+       if (ret)
+               goto err_unmap;
+
        device_init_wakeup(&pdev->dev, 1);
        return 0;