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

Greg KH
2011-06-23T21:44:21Z

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