linux-kernel - Re: [PATCH v2] gpiolib: fix reference leaks when removing GPIO chips still in use

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]

Message-ID: <ZNX7etYJrCuERn8/@smile.fi.intel.com>
Date:   Fri, 11 Aug 2023 12:12:26 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Bartosz Golaszewski <brgl@...ev.pl>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Kent Gibson <warthog618@...il.com>, linux-gpio@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v2] gpiolib: fix reference leaks when removing GPIO chips
 still in use

On Thu, Aug 10, 2023 at 08:48:46PM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> 
> After we remove a GPIO chip that still has some requested descriptors,
> gpiod_free_commit() will fail and we will never put the references to the
> GPIO device and the owning module in gpiod_free().
> 
> Rework this function to:
> - not warn on desc == NULL as this is a use-case on which most free
>   functions silently return
> - put the references to desc->gdev and desc->gdev->owner unconditionally
>   so that the release callback actually gets called when the remaining
>   references are dropped by external GPIO users

...

> +	/*
> +	 * We must not use VALIDATE_DESC_VOID() as the underlying gdev->chip
> +	 * may already be NULL but we still want to put the references.
> +	 */

Clear now!

...

> +	if (!gpiod_free_commit(desc))
>  		WARN_ON(extra_checks);

	/* Always call gpiod_free_commit() */
	WARN_ON(!gpiod_free_commit(desc) && extra_checks);

?

-- 
With Best Regards,
Andy Shevchenko