Re: [6.17 REGRESSION FIX] gpiolib: acpi: Fix using random stack memory during GPIO lookups

Andy Shevchenko
2025-09-15T06:28:29Z

On Sun, Sep 14, 2025 at 07:52:48PM +0200, Hans de Goede wrote:
> On 14-Sep-25 3:24 PM, Andy Shevchenko wrote:
> > On Sat, Sep 13, 2025 at 1:19 AM Hans de Goede <hansg@kernel.org> wrote:
> >>
> >> Before commit 8b4f52ef7a41 ("gpiolib: acpi: Deduplicate some code in
> >> __acpi_find_gpio()") and the follow-up fix commit 7c010d463372 ("gpiolib:
> >> acpi: Make sure we fill struct acpi_gpio_info"). The struct acpi_gpio_info
> >> used during lookups was part of struct acpi_gpio_lookup which gets
> >> memset() to 0 before use.
> >>
> >> And then after a successful lookup, acpi_gpio_resource_lookup() would
> >> copy the content of the zeroed acpi_gpio_lookup.info to the on
> >> stack struct acpi_gpio_info in __acpi_find_gpio(), overwriting any
> >> uninitialized memory contents there.
> >>
> >> But now instead a pointer to the on stack struct acpi_gpio_info in
> >> __acpi_find_gpio() is passed around, but that struct is never
> >> initialized.
> >>
> >> This passing around of the uninitialized struct breaks index based
> >> lookups of GpioInt GPIOs because info->quirks now contains some random
> >> on stack data which may contain ACPI_GPIO_QUIRK_ONLY_GPIOIO.
> >>
> >> Initialize the on stack struct acpi_gpio_info to 0 to fix this.
> >
> > Ah, very good catch! I missed that field that can have garbage as we
> > don't file it. I'll take it on Monday and prepare a PR next week.
>
> Thank you, but please take the more complete fix from Sébastien
> available here:
>
> https://lore.kernel.org/linux-gpio/20250912-gpiolib-acpi-fix-v1-1-1a41acbffadf@armadeus.com/
>
> That also initializes a second case of an uninitialized
> struct acpi_gpio_info on the stack.

Sure, thanks for the heads up!

--
With Best Regards,
Andy Shevchenko