linux-kernel - Re: [PATCH v3 1/4] gpiolib: Never return internal error codes to user space

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Date:   Tue, 8 Feb 2022 10:34:56 +0100
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Bartosz Golaszewski <bgolaszewski@...libre.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Suresh Balakrishnan <suresh.balakrishnan@...el.com>
Subject: Re: [PATCH v3 1/4] gpiolib: Never return internal error codes to user space

On Tue, Feb 1, 2022 at 4:28 PM Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> wrote:
>
> Currently it's possible that character device interface may return
> the error codes which are not supposed to be seen by user space.
> In this case it's EPROBE_DEFER.
>
> Wrap it to return -ENODEV instead as sysfs does.
>
> Fixes: d7c51b47ac11 ("gpio: userspace ABI for reading/writing GPIO lines")
> Fixes: 61f922db7221 ("gpio: userspace ABI for reading GPIO line events")
> Fixes: 3c0d9c635ae2 ("gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and GPIO_V2_LINE_GET_VALUES_IOCTL")
> Reported-by: Suresh Balakrishnan <suresh.balakrishnan@...el.com>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  drivers/gpio/gpiolib-cdev.c  |  6 +++---
>  drivers/gpio/gpiolib-sysfs.c |  7 ++-----
>  drivers/gpio/gpiolib.h       | 12 ++++++++++++
>  3 files changed, 17 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
> index c7b5446d01fd..ffa0256cad5a 100644
> --- a/drivers/gpio/gpiolib-cdev.c
> +++ b/drivers/gpio/gpiolib-cdev.c
> @@ -330,7 +330,7 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
>                         goto out_free_lh;
>                 }
>
> -               ret = gpiod_request(desc, lh->label);
> +               ret = gpiod_request_user(desc, lh->label);
>                 if (ret)
>                         goto out_free_lh;
>                 lh->descs[i] = desc;
> @@ -1378,7 +1378,7 @@ static int linereq_create(struct gpio_device *gdev, void __user *ip)
>                         goto out_free_linereq;
>                 }
>
> -               ret = gpiod_request(desc, lr->label);
> +               ret = gpiod_request_user(desc, lr->label);
>                 if (ret)
>                         goto out_free_linereq;
>
> @@ -1764,7 +1764,7 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
>                 }
>         }
>
> -       ret = gpiod_request(desc, le->label);
> +       ret = gpiod_request_user(desc, le->label);
>         if (ret)
>                 goto out_free_le;
>         le->desc = desc;
> diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
> index 4098bc7f88b7..44c1ad51b3fe 100644
> --- a/drivers/gpio/gpiolib-sysfs.c
> +++ b/drivers/gpio/gpiolib-sysfs.c
> @@ -475,12 +475,9 @@ static ssize_t export_store(struct class *class,
>          * they may be undone on its behalf too.
>          */
>
> -       status = gpiod_request(desc, "sysfs");
> -       if (status) {
> -               if (status == -EPROBE_DEFER)
> -                       status = -ENODEV;
> +       status = gpiod_request_user(desc, "sysfs");
> +       if (status)
>                 goto done;
> -       }
>
>         status = gpiod_set_transitory(desc, false);
>         if (!status) {
> diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
> index 30bc3f80f83e..c31f4626915d 100644
> --- a/drivers/gpio/gpiolib.h
> +++ b/drivers/gpio/gpiolib.h
> @@ -135,6 +135,18 @@ struct gpio_desc {
>
>  int gpiod_request(struct gpio_desc *desc, const char *label);
>  void gpiod_free(struct gpio_desc *desc);
> +
> +static inline int gpiod_request_user(struct gpio_desc *desc, const char *label)
> +{
> +       int ret;
> +
> +       ret = gpiod_request(desc, label);
> +       if (ret == -EPROBE_DEFER)
> +               ret = -ENODEV;
> +
> +       return ret;
> +}
> +
>  int gpiod_configure_flags(struct gpio_desc *desc, const char *con_id,
>                 unsigned long lflags, enum gpiod_flags dflags);
>  int gpio_set_debounce_timeout(struct gpio_desc *desc, unsigned int debounce);
> --
> 2.34.1
>

Queued for fixes, thanks!

Bart