linux-kernel - Re: regression from commit b0ce9ce408b6 ("gpiolib: Do not unexport GPIO on freeing")

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 14 Aug 2023 09:39:34 +0200
From:   Marek Behún <kabel@...nel.org>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Bartosz Golaszewski <bartosz.golaszewski@...aro.org>,
        linux-gpio@...r.kernel.org,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-kernel@...r.kernel.org
Subject: Re: regression from commit b0ce9ce408b6 ("gpiolib: Do not unexport
 GPIO on freeing")

On Fri, 11 Aug 2023 13:16:46 +0300
Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:

> On Tue, Aug 08, 2023 at 10:28:28AM +0200, Marek Behún wrote:
> > Hi,
> > 
> > the commit b0ce9ce408b6 ("gpiolib: Do not unexport GPIO on freeing")
> > 
> >   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b0ce9ce408b6
> > 
> > causes a regression on my mvebu arm board (haven't tested on other
> > systems), wherein if I export a GPIO to sysfs and then unexport it, it
> > does not disasppear from the /sys/class/gpio directory, and subsequent
> > writes to the export and unexport files for the gpio fail.
> > 
> >   $ cd /sys/class/gpio
> >   $ ls
> >   export       gpiochip0    gpiochip32   gpiochip512  unexport
> >   $ echo 43 >export
> >   $ ls
> >   export       gpio43       gpiochip0    gpiochip32   gpiochip512
> >   unexport
> >   $ cat gpio43/value
> >   1
> >   $ echo 43 >unexport
> >   $ ls
> >   export       gpio43       gpiochip0    gpiochip32   gpiochip512
> >   unexport
> >   $ echo 43 >unexport
> >   ash: write error: Invalid argument
> >   $ echo 43 >export
> >   ash: write error: Operation not permitted  
> 
> Can you test the following change (I'll submit a formal patch if it works)?
> 
> diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
> index 530dfd19d7b5..b10a9b5598b2 100644
> --- a/drivers/gpio/gpiolib-sysfs.c
> +++ b/drivers/gpio/gpiolib-sysfs.c
> @@ -515,8 +515,9 @@ static ssize_t unexport_store(const struct class *class,
>  	 * they may be undone on its behalf too.
>  	 */
>  	if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
> +		gpiod_unexport(desc);
> +		gpiod_free(desc);
>  		status = 0;
> -		gpiod_free(desc);
>  	}
>  done:
>  	if (status)
> 

tested, works.

Please add Fixes tag when sending the patch