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Subject: Re: [PATCH] lib/vsprintf: add %pT[C012] format specifier
From: Joe Perches <joe@perches.com>
To: Kees Cook <keescook@chromium.org>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
        Andrew Morton <akpm@linux-foundation.org>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Jiri Kosina <jkosina@suse.cz>, Al Viro <viro@zeniv.linux.org.uk>,
        "David S. Miller" <davem@davemloft.net>,
        LKML <linux-kernel@vger.kernel.org>
Date: Fri, 03 Jan 2014 09:39:08 -0800
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On Fri, 2014-01-03 at 09:08 -0800, Kees Cook wrote:
> I'm on board with the idea of embedding comm/pid/whatever,

I still think the space reduction isn't worth the
complication.

>  but I
> either missed or do not understand why a second format-start character
> is being added. I think this will complicate audits and maybe trigger
> weird info leaks (imagine printing a string that was %-escaped, but
> not 0x1A-escaped?)
> Why not use % followed by 0x1A to be the start code, instead of just 0x1A?

gcc would bleat an error for
	"unknown conversion type character 0x1a in format".