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Subject: Re: unsafe printk
From: Albert Cahalan <albert@users.sf.net>
To: Pavel Machek <pavel@ucw.cz>
Cc: linux-kernel mailing list <linux-kernel@vger.kernel.org>
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	 <20031017095240.GB7738@elf.ucw.cz>
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On Fri, 2003-10-17 at 05:52, Pavel Machek wrote:
> Hi!
> 
> > Suppose I name an executable this:
> > "\n<0>Oops: EIP=0"
> > 
> > That comes out as a KERN_EMERG log message,
> > hitting the console and maybe a pager even.
> > 
> > There seem to be a number of places in the
> > kernel that printk current->comm without
> > concern for what it may contain.
> > 
> > Escape codes and non-ASCII can make for some
> > interesting log messages as well. Terminals
> > may have some programmable keys or answerback
> > messages. So one day root is using grep on
> > the log files, and they program the answerback
> > string to contain a "\r\nrm -r /\r\n"...
> 
> Or at least you can make his terminal pink ;-). Unfortunately same
> problem is with userland programs; root does ps and his terminal goes
> pink. Sanitizing kernel messages would be good start, but ps&friends
> and ls&friends need to be sanitized, too.

Both ps and ls are protected. At least with the
procps-3.1.xx code, w and top are also protected.

So anyway, what to do about the kernel messages?
One option is to just mangle comm up front. Another
option is to provide a formatting function for
safe printing.