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SubjectRe: [PATCH 1/2] rtc: st-lpc: fix possible race condition
Date
Hi Alexandre

On 05/20/2018 02:33 PM, 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.
>
> Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
> ---
> drivers/rtc/rtc-st-lpc.c | 24 +++++++++---------------
> 1 file changed, 9 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/rtc/rtc-st-lpc.c b/drivers/rtc/rtc-st-lpc.c
> index d5222667f892..2f1ef2c28740 100644
> --- a/drivers/rtc/rtc-st-lpc.c
> +++ b/drivers/rtc/rtc-st-lpc.c
> @@ -212,6 +212,10 @@ static int st_rtc_probe(struct platform_device *pdev)
> if (!rtc)
> return -ENOMEM;
>
> + rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
> + if (IS_ERR(rtc->rtc_dev))
> + return PTR_ERR(rtc->rtc_dev);
> +
> spin_lock_init(&rtc->lock);
>
> res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> @@ -253,26 +257,17 @@ static int st_rtc_probe(struct platform_device *pdev)
>
> platform_set_drvdata(pdev, rtc);
>
> - rtc->rtc_dev = rtc_device_register("st-lpc-rtc", &pdev->dev,
> - &st_rtc_ops, THIS_MODULE);
> - if (IS_ERR(rtc->rtc_dev)) {
> + rtc->rtc_dev->ops = &st_rtc_ops;
> +
> + ret = rtc_register_device(rtc->rtc_dev);
> + if (ret) {
> clk_disable_unprepare(rtc->clk);
> - return PTR_ERR(rtc->rtc_dev);
> + return ret;
> }
>
> return 0;
> }
>
> -static int st_rtc_remove(struct platform_device *pdev)
> -{
> - struct st_rtc *rtc = platform_get_drvdata(pdev);
> -
> - if (likely(rtc->rtc_dev))
> - rtc_device_unregister(rtc->rtc_dev);
> -
> - return 0;
> -}
> -
> #ifdef CONFIG_PM_SLEEP
> static int st_rtc_suspend(struct device *dev)
> {
> @@ -325,7 +320,6 @@ static struct platform_driver st_rtc_platform_driver = {
> .of_match_table = st_rtc_match,
> },
> .probe = st_rtc_probe,
> - .remove = st_rtc_remove,
> };
>
> module_platform_driver(st_rtc_platform_driver);
>

Acked-by: Patrice Chotard <patrice.chotard@st.com>

Thanks

Patrice
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