[PATCH v2] gpio: cdev: check if uAPI v2 config attributes are correctly zeroed

[Bartosz Golaszewski]

We check the padding of other uAPI v2 structures but not that of line
config attributes. For used attributes: check if their padding is
zeroed, for unused: check if the entire structure is zeroed.

Fixes: 3c0d9c635ae2 ("gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and GPIO_V2_LINE_GET_VALUES_IOCTL")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxxxxxxxx>
---
Changes in v2:
- Make checking even stricter: check if padding is zeroed for used
  attributes, for unused ones: check if the entire struct is zeroed
- Link to v1: https://patch.msgid.link/20260519-gpio-cdev-attr-padding-check-v1-1-a0c6d4a698bf@xxxxxxxxxxxxxxxx
---
 drivers/gpio/gpiolib-cdev.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index f36b7c06996d70b2286edbd181899e4c572b9086..edbcc86e4b26f88036ed12c13055bb2c371fb6a3 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -1194,6 +1194,15 @@ static int gpio_v2_line_config_validate(struct gpio_v2_line_config *lc,
 	if (!mem_is_zero(lc->padding, sizeof(lc->padding)))
 		return -EINVAL;
 
+	for (i = 0; i < lc->num_attrs; i++) {
+		if (lc->attrs[i].attr.padding != 0)
+			return -EINVAL;
+	}
+
+	if (!mem_is_zero(&lc->attrs[i],
+			 (GPIO_V2_LINE_NUM_ATTRS_MAX - lc->num_attrs) * sizeof(*lc->attrs)))
+		return -EINVAL;
+
 	for (i = 0; i < num_lines; i++) {
 		flags = gpio_v2_line_config_flags(lc, i);
 		ret = gpio_v2_line_flags_validate(flags);

---
base-commit: 6a50ba100ace43f43c87384367eb2d2605fcc16c
change-id: 20260519-gpio-cdev-attr-padding-check-7e52c98a3de7

Best regards,
-- 
Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxxxxxxxx>