linux-kernel - Re: [PATCH 1/2] remove all uses of printf's %n

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Date:	Thu, 19 Sep 2013 21:53:40 -0700
From:	Kees Cook <keescook@...omium.org>
To:	Joe Perches <joe@...ches.com>
Cc:	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
	Jiri Slaby <jslaby@...e.cz>, Al Viro <viro@...iv.linux.org.uk>,
	Pavel Emelyanov <xemul@...nvz.org>,
	remi.denis-courmont@...ia.com, LKML <linux-kernel@...r.kernel.org>,
	netdev@...r.kernel.org, linux-sctp@...r.kernel.org,
	George Spelvin <linux@...izon.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dan Carpenter <dan.carpenter@...cle.com>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Jan Beulich <JBeulich@...e.com>,
	Motohiro KOSAKI <kosaki.motohiro@...il.com>
Subject: Re: [PATCH 1/2] remove all uses of printf's %n

On Thu, Sep 19, 2013 at 9:23 PM, Joe Perches <joe@...ches.com> wrote:
> On Fri, 2013-09-20 at 13:09 +0900, Tetsuo Handa wrote:
>> Hello.
>
> Tetsuo-san:
>
>> We are discussing about removal of %n support from vsnprintf() at
>> https://lkml.org/lkml/2013/9/16/52 , and you are using %n in seq_printf().
>
> Well, I'm not using (mere alcohol isn't using, right?)
> but I still have the same question for Al.
>
> Are there any races here?

All the call sites I examined were linear. FWIW, I didn't see any races.

-Kees

>
>> I posted https://lkml.org/lkml/diff/2013/9/19/53/1 which introduces
>> seq_setwidth() / seq_pad() which can avoid use of %n in seq_printf().
>
> I still think adding last_len, last_rtn
> is sensible.
>
>



-- 
Kees Cook
Chrome OS Security
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