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

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

[Antonio Quartulli]

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@mandelbit.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

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

[Bartosz Golaszewski]

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


On Mon, 23 Jun 2025 00:02:21 +0200, Antonio Quartulli wrote:
> 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`.
> 
> [...]

Thanks for the catch. I tweaked the commit message and added the Fixes: tag.
Applied, thanks!

[1/1] gpiolib-sysfs: fix use-after-free in error path
      https://git.kernel.org/brgl/linux/c/e6bb78570f7d531622ec572ef9ddbe6e66ff16ce

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