linux-kernel - Re: [PATCH] sanitize task->comm to avoid leaking escape codes

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Message-ID: <20100623212831.GA4809@outflux.net>
Date:	Wed, 23 Jun 2010 14:28:31 -0700
From:	Kees Cook <kees.cook@...onical.com>
To:	Alexey Dobriyan <adobriyan@...il.com>
Cc:	Oleg Nesterov <oleg@...hat.com>, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Neil Horman <nhorman@...driver.com>,
	Roland McGrath <roland@...hat.com>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] sanitize task->comm to avoid leaking escape codes

On Wed, Jun 23, 2010 at 11:23:35PM +0300, Alexey Dobriyan wrote:
> On Wed, Jun 23, 2010 at 09:41:45PM +0200, Oleg Nesterov wrote:
> > On 06/23, Kees Cook wrote:
>  
> > > -extern char *get_task_comm(char *to, struct task_struct *tsk);
> > > +#define get_task_comm(buf, task) get_task_comm_size(buf, sizeof(buf), task)
> > > +extern char *get_task_comm_size(char *to, size_t len, struct task_struct *tsk);
> > 
> > Oh, but this means that get_task_comm(ptr, task) doesn't work?
> 
> The number of users is so small, and everyone uses TASK_COMM_LEN,
> so maybe nothing should be done or "char buf[TASK_COMM_LEN]"?

I couldn't handle the pathological use of strncpy(dest, src, sizeof(src))
that is currently in get_task_comm; that's just asking for trouble.

If someone wants to use a ptr for get_task_comm, they would get to call
get_task_comm_size() instead?

-Kees

-- 
Kees Cook
Ubuntu Security Team
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