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

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Date:	Wed, 22 Oct 2014 16:26:38 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Kees Cook <keescook@...omium.org>
Cc:	linux-kernel@...r.kernel.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>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: Re: [PATCH] sysctl: terminate strings also on \r

On Tue, 21 Oct 2014 13:21:37 -0700 Kees Cook <keescook@...omium.org> 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.
> 
> ...
>
> --- 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;
>  		}

There are no valid uses of \r in a procfs write?
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