linux-kernel - Re: [PATCH 0/5] kallsyms: make kallsym APIs more safe with scnprintf

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] [day] [month] [year] [list]

Message-ID: <YqmR9ZeiwMQLyKDu@alley>
Date:   Wed, 15 Jun 2022 10:01:57 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     Kees Cook <keescook@...omium.org>
Cc:     Christoph Hellwig <hch@...radead.org>,
        Maninder Singh <maninder1.s@...sung.com>, bcain@...cinc.com,
        mpe@...erman.id.au, benh@...nel.crashing.org, paulus@...ba.org,
        hca@...ux.ibm.com, gor@...ux.ibm.com, agordeev@...ux.ibm.com,
        borntraeger@...ux.ibm.com, svens@...ux.ibm.com, satishkh@...co.com,
        sebaddel@...co.com, kartilak@...co.com, jejb@...ux.ibm.com,
        martin.petersen@...cle.com, mcgrof@...nel.org,
        jason.wessel@...driver.com, daniel.thompson@...aro.org,
        dianders@...omium.org, naveen.n.rao@...ux.ibm.com,
        anil.s.keshavamurthy@...el.com, davem@...emloft.net,
        mhiramat@...nel.org, peterz@...radead.org, mingo@...hat.com,
        will@...nel.org, longman@...hat.com, boqun.feng@...il.com,
        rostedt@...dmis.org, senozhatsky@...omium.org,
        andriy.shevchenko@...ux.intel.com, linux@...musvillemoes.dk,
        akpm@...ux-foundation.org, arnd@...db.de,
        linux-hexagon@...r.kernel.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org,
        linux-scsi@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-modules@...r.kernel.org,
        kgdb-bugreport@...ts.sourceforge.net, v.narang@...sung.com,
        onkarnath.1@...sung.com
Subject: Re: [PATCH 0/5] kallsyms: make kallsym APIs more safe with scnprintf

On Mon 2022-05-23 12:39:12, Kees Cook wrote:
> On Sat, May 21, 2022 at 11:07:52PM -0700, Christoph Hellwig wrote:
> > On Fri, May 20, 2022 at 02:06:56PM +0530, Maninder Singh wrote:
> > > kallsyms functionality depends on KSYM_NAME_LEN directly.
> > > but if user passed array length lesser than it, sprintf
> > > can cause issues of buffer overflow attack.
> > > 
> > > So changing *sprint* and *lookup* APIs in this patch set
> > > to have buffer size as an argument and replacing sprintf with
> > > scnprintf.
> > 
> > This is still a pretty horrible API.  Passing something like
> > a struct seq_buf seems like the much better API here.  Also with
> > the amount of arguments and by reference passing it might be worth
> > to pass them as a structure while you're at it.
> 
> Yeah, I agree. It really seems like seq_buf would be nicer.

There is a new patchset that is trying to use this kind of buffer
in vsprintf.

It introduces another buffer struct because vsprintf() needs a bit
different semantic than the one used in seq_buf. But it actually
replaces seq_buf() in the end. I am not sure if this is the right
approach.

Anyway, the initial API is very simple, see
https://lore.kernel.org/r/20220604193042.1674951-2-kent.overstreet@gmail.com

And it makes the internal vsprintf() API more sane, see
https://lore.kernel.org/r/20220604193042.1674951-4-kent.overstreet@gmail.com

It would eventually solve also concerns about the kallsysms API.
Any comments on the new printbuf API are much appreaciated.

Best Regards,
Petr