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>

1 files changed, 9 insertions, 7 deletions

diff --git a/drivers/rtc/rtc-sh.c b/drivers/rtc/rtc-sh.c
index 7fffe6da9478..d9e67ca4b7b9 100644
--- 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;