linux-kernel - Re: [PATCH v8 12/12] zram: use ATTRIBUTE_GROUPS to fix sysfs deadlock module removal

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: <YWSCWInXaXEpFQGc@bombadil.infradead.org>
Date:   Mon, 11 Oct 2021 11:28:40 -0700
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     Kees Cook <keescook@...omium.org>
Cc:     tj@...nel.org, gregkh@...uxfoundation.org,
        akpm@...ux-foundation.org, minchan@...nel.org, jeyu@...nel.org,
        shuah@...nel.org, bvanassche@....org, dan.j.williams@...el.com,
        joe@...ches.com, tglx@...utronix.de, rostedt@...dmis.org,
        linux-spdx@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-block@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 12/12] zram: use ATTRIBUTE_GROUPS to fix sysfs
 deadlock module removal

On Tue, Oct 05, 2021 at 01:57:00PM -0700, Kees Cook wrote:
> On Mon, Sep 27, 2021 at 09:38:05AM -0700, Luis Chamberlain wrote:
> > The ATTRIBUTE_GROUPS is typically used to avoid boiler plate
> > code which is used in many drivers. Embracing ATTRIBUTE_GROUPS was
> > long due on the zram driver, however a recent fix for sysfs allows
> > users of ATTRIBUTE_GROUPS to also associate a module to the group
> > attribute.
> 
> Does this mean that other modules using sysfs but _not_
> ATTRIBUTE_GROUPS() are still vulnerable to potential use-after-free of
> the kernfs fops?

The issue is not UAF, its the possible deadlock, but in that sense, yes.
If they don't use ATTRIBUTE_GROUPS() then there is no information being
provided to sysfs about the module owner.

  Luis