linux-kernel - Re: [PATCH] sysctl: terminate strings also on \r

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Message-ID: <20141022133919.GS4977@linux.vnet.ibm.com>
Date:	Wed, 22 Oct 2014 06:39:19 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	Kees Cook <keescook@...omium.org>
Cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...nel.org>, Rik van Riel <riel@...hat.com>,
	David Rientjes <rientjes@...gle.com>,
	Aaron Tomlin <atomlin@...hat.com>,
	Dario Faggioli <raistlin@...ux.it>,
	Andi Kleen <ak@...ux.intel.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Jens Axboe <axboe@...com>
Subject: Re: [PATCH] sysctl: terminate strings also on \r

On Tue, Oct 21, 2014 at 01:21:37PM -0700, Kees Cook wrote:
> From: Paul Wise <pabs3@...edaddy.net>
> 
> This partially mitigates a common strategy used by attackers for hiding
> the full contents of strings in procfs from naive sysadmins who use cat,
> more or sysctl to inspect the contents of strings in procfs.
> 
> References: http://www.jakoblell.com/blog/2014/05/07/hacking-contest-hiding-stuff-from-the-terminal/
> Signed-off-by: Paul Wise <pabs3@...edaddy.net>
> Signed-off-by: Kees Cook <keescook@...omium.org>

Acked-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>

> ---
>  kernel/sysctl.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index 4aada6d9fe74..c34c9414caac 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -1739,7 +1739,7 @@ static int _proc_do_string(char *data, int maxlen, int write,
>  		while ((p - buffer) < *lenp && len < maxlen - 1) {
>  			if (get_user(c, p++))
>  				return -EFAULT;
> -			if (c == 0 || c == '\n')
> +			if (c == 0 || c == '\n' || c == '\r')
>  				break;
>  			data[len++] = c;
>  		}
> -- 
> 1.9.1
> 
> 
> -- 
> Kees Cook
> Chrome OS Security
> 

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