rtc: mxc: 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.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

diff --git a/drivers/rtc/rtc-mxc.c b/drivers/rtc/rtc-mxc.c
index 708b9e9..d9a038a 100644 (file)
--- a/drivers/rtc/rtc-mxc.c
+++ b/drivers/rtc/rtc-mxc.c
@@ -340,6 +340,13 @@ static int mxc_rtc_probe(struct platform_device *pdev)
        if (IS_ERR(pdata->ioaddr))
                return PTR_ERR(pdata->ioaddr);
 
+       rtc = devm_rtc_allocate_device(&pdev->dev);
+       if (IS_ERR(rtc))
+               return PTR_ERR(rtc);
+
+       pdata->rtc = rtc;
+       rtc->ops = &mxc_rtc_ops;
+
        pdata->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
        if (IS_ERR(pdata->clk_ipg)) {
                dev_err(&pdev->dev, "unable to get ipg clock!\n");
@@ -402,14 +409,9 @@ static int mxc_rtc_probe(struct platform_device *pdev)
                        dev_err(&pdev->dev, "failed to enable irq wake\n");
        }
 
-       rtc = devm_rtc_device_register(&pdev->dev, pdev->name, &mxc_rtc_ops,
-                                 THIS_MODULE);
-       if (IS_ERR(rtc)) {
-               ret = PTR_ERR(rtc);
+       ret = rtc_register_device(rtc);
+       if (ret)
                goto exit_put_clk_ref;
-       }
-
-       pdata->rtc = rtc;
 
        return 0;