linux-kernel - [PATCH 1/8] gpiolib: check the return value of gpio_chip::get

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Message-Id: <20250210-gpio-sanitize-retvals-v1-1-12ea88506cb2@linaro.org>
Date: Mon, 10 Feb 2025 11:51:55 +0100
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Linus Walleij <linus.walleij@...aro.org>, 
 Bartosz Golaszewski <brgl@...ev.pl>
Cc: linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Bartosz Golaszewski <bartosz.golaszewski@...aro.org>, 
 stable@...r.kernel.org
Subject: [PATCH 1/8] gpiolib: check the return value of
 gpio_chip::get_direction()

From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>

As per the API contract - gpio_chip::get_direction() may fail and return
a negative error number. However, we treat it as if it always returned 0
or 1. Check the return value of the callback and propagate the error
number up the stack.

Cc: stable@...r.kernel.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
---
 drivers/gpio/gpiolib.c | 44 +++++++++++++++++++++++++++++---------------
 1 file changed, 29 insertions(+), 15 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 679ed764cb14..5d3774dc748b 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1057,8 +1057,11 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
 		desc->gdev = gdev;
 
 		if (gc->get_direction && gpiochip_line_is_valid(gc, desc_index)) {
-			assign_bit(FLAG_IS_OUT,
-				   &desc->flags, !gc->get_direction(gc, desc_index));
+			ret = gc->get_direction(gc, desc_index);
+			if (ret < 0)
+				goto err_cleanup_desc_srcu;
+
+			assign_bit(FLAG_IS_OUT, &desc->flags, !ret);
 		} else {
 			assign_bit(FLAG_IS_OUT,
 				   &desc->flags, !gc->direction_input);
@@ -2728,13 +2731,18 @@ int gpiod_direction_input_nonotify(struct gpio_desc *desc)
 	if (guard.gc->direction_input) {
 		ret = guard.gc->direction_input(guard.gc,
 						gpio_chip_hwgpio(desc));
-	} else if (guard.gc->get_direction &&
-		  (guard.gc->get_direction(guard.gc,
-					   gpio_chip_hwgpio(desc)) != 1)) {
-		gpiod_warn(desc,
-			   "%s: missing direction_input() operation and line is output\n",
-			   __func__);
-		return -EIO;
+	} else if (guard.gc->get_direction) {
+		ret = guard.gc->get_direction(guard.gc,
+					      gpio_chip_hwgpio(desc));
+		if (ret < 0)
+			return ret;
+
+		if (ret != GPIO_LINE_DIRECTION_IN) {
+			gpiod_warn(desc,
+				   "%s: missing direction_input() operation and line is output\n",
+				    __func__);
+			return -EIO;
+		}
 	}
 	if (ret == 0) {
 		clear_bit(FLAG_IS_OUT, &desc->flags);
@@ -2771,12 +2779,18 @@ static int gpiod_direction_output_raw_commit(struct gpio_desc *desc, int value)
 						 gpio_chip_hwgpio(desc), val);
 	} else {
 		/* Check that we are in output mode if we can */
-		if (guard.gc->get_direction &&
-		    guard.gc->get_direction(guard.gc, gpio_chip_hwgpio(desc))) {
-			gpiod_warn(desc,
-				"%s: missing direction_output() operation\n",
-				__func__);
-			return -EIO;
+		if (guard.gc->get_direction) {
+			ret = guard.gc->get_direction(guard.gc,
+						      gpio_chip_hwgpio(desc));
+			if (ret < 0)
+				return ret;
+
+			if (ret != GPIO_LINE_DIRECTION_OUT) {
+				gpiod_warn(desc,
+					   "%s: missing direction_output() operation\n",
+					   __func__);
+				return -EIO;
+			}
 		}
 		/*
 		 * If we can't actively set the direction, we are some

-- 
2.45.2