linux-kernel - [PATCH] gpiolib-sysfs: fix use-after-free in error path

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Message-ID: <20250622220221.28025-1-antonio@mandelbit.com>
Date: Mon, 23 Jun 2025 00:02:21 +0200
From: Antonio Quartulli <antonio@...delbit.com>
To: linux-gpio@...r.kernel.org
Cc: linus.walleij@...aro.org,
	brgl@...ev.pl,
	linux-kernel@...r.kernel.org,
	Antonio Quartulli <antonio@...delbit.com>
Subject: [PATCH] gpiolib-sysfs: fix use-after-free in error path

When invoking device_create_with_groups() its return
value is stored in `data->cdev_base`.
However, in case of faiure, `data` is first
freed and then derefernced in order to return
`data->cdev_base`.

Fix the use-after-free by extracting the error
code before free'ing `data`.

This issue was reported by Coverity Scan.

Addresses-Coverity-ID: 1644512 ("Memory - illegal accesses  (USE_AFTER_FREE)")
Signed-off-by: Antonio Quartulli <antonio@...delbit.com>
---
 drivers/gpio/gpiolib-sysfs.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 956411fc467a..c4c21e25c682 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -741,6 +741,7 @@ int gpiochip_sysfs_register(struct gpio_device *gdev)
 	struct gpiodev_data *data;
 	struct gpio_chip *chip;
 	struct device *parent;
+	int err;
 
 	/*
 	 * Many systems add gpio chips for SOC support very early,
@@ -781,8 +782,9 @@ int gpiochip_sysfs_register(struct gpio_device *gdev)
 						    GPIOCHIP_NAME "%d",
 						    chip->base);
 	if (IS_ERR(data->cdev_base)) {
+		err = PTR_ERR(data->cdev_base);
 		kfree(data);
-		return PTR_ERR(data->cdev_base);
+		return err;
 	}
 
 	return 0;
-- 
2.49.0