From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Date: Tue, 11 Mar 2025 14:19:51 +0000 (+0100)
Subject: gpiolib: don't allow setting values on input lines
X-Git-Tag: v6.16-rc1~169^2~105
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=92ac7de3175e3c17cbb76ae752b598cfb9dadf49;p=linux-block.git

gpiolib: don't allow setting values on input lines

Some drivers as well as the character device and sysfs code check
whether the line actually is in output mode before allowing the user to
set a value.

However, GPIO value setters now return integer values and can indicate
failures. This allows us to move these checks into the core code.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250311-gpio-set-check-output-v1-1-d971bca9e6fa@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index 107d75558b5a..e6a289fa0f8f 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -1366,9 +1366,6 @@ static long linereq_set_values(struct linereq *lr, void __user *ip)
 	/* scan requested lines to determine the subset to be set */
 	for (num_set = 0, i = 0; i < lr->num_lines; i++) {
 		if (lv.mask & BIT_ULL(i)) {
-			/* setting inputs is not allowed */
-			if (!test_bit(FLAG_IS_OUT, &lr->lines[i].desc->flags))
-				return -EPERM;
 			/* add to compacted values */
 			if (lv.bits & BIT_ULL(i))
 				__set_bit(num_set, vals);
diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 1acfa43bf1ab..4a3aa09dad9d 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -134,17 +134,15 @@ static ssize_t value_store(struct device *dev,
 	long value;
 
 	status = kstrtol(buf, 0, &value);
+	if (status)
+		return status;
 
 	guard(mutex)(&data->mutex);
 
-	if (!test_bit(FLAG_IS_OUT, &desc->flags))
-		return -EPERM;
-
+	status = gpiod_set_value_cansleep(desc, value);
 	if (status)
 		return status;
 
-	gpiod_set_value_cansleep(desc, value);
-
 	return size;
 }
 static DEVICE_ATTR_PREALLOC(value, S_IWUSR | S_IRUGO, value_show, value_store);
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index b8197502a5ac..8252a671d720 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -3593,6 +3593,9 @@ static int gpio_set_open_source_value_commit(struct gpio_desc *desc, bool value)
 
 static int gpiod_set_raw_value_commit(struct gpio_desc *desc, bool value)
 {
+	if (unlikely(!test_bit(FLAG_IS_OUT, &desc->flags)))
+		return -EPERM;
+
 	CLASS(gpio_chip_guard, guard)(desc);
 	if (!guard.gc)
 		return -ENODEV;
@@ -3664,6 +3667,12 @@ int gpiod_set_array_value_complex(bool raw, bool can_sleep,
 		if (!can_sleep)
 			WARN_ON(array_info->gdev->can_sleep);
 
+		for (i = 0; i < array_size; i++) {
+			if (unlikely(!test_bit(FLAG_IS_OUT,
+					       &desc_array[i]->flags)))
+				return -EPERM;
+		}
+
 		guard(srcu)(&array_info->gdev->srcu);
 		gc = srcu_dereference(array_info->gdev->chip,
 				      &array_info->gdev->srcu);
@@ -3723,6 +3732,9 @@ int gpiod_set_array_value_complex(bool raw, bool can_sleep,
 			int hwgpio = gpio_chip_hwgpio(desc);
 			int value = test_bit(i, value_bitmap);
 
+			if (unlikely(!test_bit(FLAG_IS_OUT, &desc->flags)))
+				return -EPERM;
+
 			/*
 			 * Pins applicable for fast input but not for
 			 * fast output processing may have been already