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

Hans de Goede
2025-09-12T22:19:03Z

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.

Fixes: 8b4f52ef7a41 ("gpiolib: acpi: Deduplicate some code in __acpi_find_gpio()")
Fixes: 7c010d463372 ("gpiolib: acpi: Make sure we fill struct acpi_gpio_info")
Signed-off-by: Hans de Goede <hansg@kernel.org>
---
drivers/gpio/gpiolib-acpi-core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpio/gpiolib-acpi-core.c b/drivers/gpio/gpiolib-acpi-core.c
index 12b24a717e43..1cc5d0702ee1 100644
--- a/drivers/gpio/gpiolib-acpi-core.c
+++ b/drivers/gpio/gpiolib-acpi-core.c
@@ -942,7 +942,7 @@ struct gpio_desc *acpi_find_gpio(struct fwnode_handle *fwnode,
{
struct acpi_device *adev = to_acpi_device_node(fwnode);
bool can_fallback = acpi_can_fallback_to_crs(adev, con_id);
- struct acpi_gpio_info info;
+ struct acpi_gpio_info info = { };
struct gpio_desc *desc;

desc = __acpi_find_gpio(fwnode, con_id, idx, can_fallback, &info);
--
2.51.0