From: Rafael J. Wysocki rafael.j.wysocki@intel.com
commit 4919d3eb2ec0ee364f7e3cf2d99646c1b224fae8 upstream.
Because acpi_install_fixed_event_handler() enables the event automatically on success, it is incorrect to call it before the handler routine passed to it is ready to handle events.
Unfortunately, the rtc-cmos driver does exactly the incorrect thing by calling cmos_wake_setup(), which passes rtc_handler() to acpi_install_fixed_event_handler(), before cmos_do_probe(), because rtc_handler() uses dev_get_drvdata() to get to the cmos object pointer and the driver data pointer is only populated in cmos_do_probe().
This leads to a NULL pointer dereference in rtc_handler() on boot if the RTC fixed event happens to be active at the init time.
To address this issue, change the initialization ordering of the driver so that cmos_wake_setup() is always called after a successful cmos_do_probe() call.
While at it, change cmos_pnp_probe() to call cmos_do_probe() after the initial if () statement used for computing the IRQ argument to be passed to cmos_do_probe() which is cleaner than calling it in each branch of that if () (local variable "irq" can be of type int, because it is passed to that function as an argument of type int).
Note that commit 6492fed7d8c9 ("rtc: rtc-cmos: Do not check ACPI_FADT_LOW_POWER_S0") caused this issue to affect a larger number of systems, because previously it only affected systems with ACPI_FADT_LOW_POWER_S0 set, but it is present regardless of that commit.
Fixes: 6492fed7d8c9 ("rtc: rtc-cmos: Do not check ACPI_FADT_LOW_POWER_S0") Fixes: a474aaedac99 ("rtc-cmos: move wake setup from ACPI glue into RTC driver") Link: https://lore.kernel.org/linux-acpi/20221010141630.zfzi7mk7zvnmclzy@techsingu... Reported-by: Mel Gorman mgorman@techsingularity.net Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Reviewed-by: Bjorn Helgaas bhelgaas@google.com Tested-by: Mel Gorman mgorman@techsingularity.net Link: https://lore.kernel.org/r/5629262.DvuYhMxLoT@kreacher Signed-off-by: Alexandre Belloni alexandre.belloni@bootlin.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/rtc/rtc-cmos.c | 29 +++++++++++++++++++---------- 1 file changed, 19 insertions(+), 10 deletions(-)
--- a/drivers/rtc/rtc-cmos.c +++ b/drivers/rtc/rtc-cmos.c @@ -1352,10 +1352,10 @@ static void cmos_check_acpi_rtc_status(s
static int cmos_pnp_probe(struct pnp_dev *pnp, const struct pnp_device_id *id) { - cmos_wake_setup(&pnp->dev); + int irq, ret;
if (pnp_port_start(pnp, 0) == 0x70 && !pnp_irq_valid(pnp, 0)) { - unsigned int irq = 0; + irq = 0; #ifdef CONFIG_X86 /* Some machines contain a PNP entry for the RTC, but * don't define the IRQ. It should always be safe to @@ -1364,13 +1364,17 @@ static int cmos_pnp_probe(struct pnp_dev if (nr_legacy_irqs()) irq = RTC_IRQ; #endif - return cmos_do_probe(&pnp->dev, - pnp_get_resource(pnp, IORESOURCE_IO, 0), irq); } else { - return cmos_do_probe(&pnp->dev, - pnp_get_resource(pnp, IORESOURCE_IO, 0), - pnp_irq(pnp, 0)); + irq = pnp_irq(pnp, 0); } + + ret = cmos_do_probe(&pnp->dev, pnp_get_resource(pnp, IORESOURCE_IO, 0), irq); + if (ret) + return ret; + + cmos_wake_setup(&pnp->dev); + + return 0; }
static void cmos_pnp_remove(struct pnp_dev *pnp) @@ -1454,10 +1458,9 @@ static inline void cmos_of_init(struct p static int __init cmos_platform_probe(struct platform_device *pdev) { struct resource *resource; - int irq; + int irq, ret;
cmos_of_init(pdev); - cmos_wake_setup(&pdev->dev);
if (RTC_IOMAPPED) resource = platform_get_resource(pdev, IORESOURCE_IO, 0); @@ -1467,7 +1470,13 @@ static int __init cmos_platform_probe(st if (irq < 0) irq = -1;
- return cmos_do_probe(&pdev->dev, resource, irq); + ret = cmos_do_probe(&pdev->dev, resource, irq); + if (ret) + return ret; + + cmos_wake_setup(&pdev->dev); + + return 0; }
static int cmos_platform_remove(struct platform_device *pdev)