linux-kernel - Re: [PATCH] kernel: escape non-ASCII and control characters in printk()

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Message-ID: <20110623214421.GC7184@suse.de>
Date:	Thu, 23 Jun 2011 14:44:21 -0700
From:	Greg KH <gregkh@...e.de>
To:	Matthew Garrett <mjg59@...f.ucam.org>
Cc:	Vasiliy Kulikov <segoon@...nwall.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	James Morris <jmorris@...ei.org>, Ingo Molnar <mingo@...e.hu>,
	Namhyung Kim <namhyung@...il.com>,
	kernel-hardening@...ts.openwall.com, linux-kernel@...r.kernel.org,
	security@...nel.org
Subject: Re: [PATCH] kernel: escape non-ASCII and control characters in
 printk()

On Thu, Jun 23, 2011 at 02:36:05PM +0100, Matthew Garrett wrote:
> On Wed, Jun 22, 2011 at 08:37:42AM -0700, Greg KH wrote:
> > On Wed, Jun 22, 2011 at 01:53:41PM +0400, Vasiliy Kulikov wrote:
> > > This patch escapes all characters outside of allowed '\n' plus 0x20-0x7E
> > > charset passed to printk().
> > > 
> > > There are numerous printk() instances with user supplied input as "%s"
> > > data, and unprivileged user may craft log messages with substrings
> > > containing control characters via these printk()s.  Control characters
> > > might fool root viewing the logs via tty.
> > 
> > There are "numerous" places this could happen?
> 
> USB product identifiers?

That's one, sure, but the ability to overwrite something else that you
don't want someone to see based on plugging in a USB device is pretty
slim.  If I can plug any type of USB device I want into the system, odds
are I just owned it anyway...

greg k-h
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