From: =?ISO-8859-1?Q?Nicolas_de_Peslo=FCan?= 
	<nicolas.2p.debian@gmail.com>
Subject: Re: [PATCH] core: dev: don't call BUG() on bad input
Date: Mon, 14 Feb 2011 14:01:44 +0100
Lines: 40
Message-ID: <4D5927B8.2070704@gmail.com>
References: <1297680967-11893-1-git-send-email-segoon@openwall.com> <4D591D04.4050000@gmail.com> <20110214122313.GA10062@albatros>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1;
	format=flowed
Content-Transfer-Encoding: QUOTED-PRINTABLE
Cc: linux-kernel@vger.kernel.org,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <eric.dumazet@gmail.com>,
	Tom Herbert <therbert@google.com>,
	Changli Gao <xiaosuo@gmail.com>,
	Jesse Gross <jesse@nicira.com>, netdev@vger.kernel.org
To: Vasiliy Kulikov <segoon@openwall.com>
X-From: netdev-owner@vger.kernel.org Mon Feb 14 14:02:23 2011
Return-path: <netdev-owner@vger.kernel.org>
Envelope-to: linux-netdev-2@lo.gmane.org
Received: from vger.kernel.org ([209.132.180.67])
	by lo.gmane.org with esmtp (Exim 4.69)
	(envelope-from <netdev-owner@vger.kernel.org>)
	id 1Poy4M-0006df-J5
	for linux-netdev-2@lo.gmane.org; Mon, 14 Feb 2011 14:02:22 +0100
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1754233Ab1BNNBu convert rfc822-to-quoted-printable (ORCPT
	<rfc822;linux-netdev-2@m.gmane.org>); Mon, 14 Feb 2011 08:01:50 -0500
Received: from mail-fx0-f46.google.com ([209.85.161.46]:54545 "EHLO
	mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1753647Ab1BNNBs (ORCPT
	<rfc822;netdev@vger.kernel.org>); Mon, 14 Feb 2011 08:01:48 -0500
Received: by fxm20 with SMTP id 20so5178314fxm.19
        for <multiple recipients>; Mon, 14 Feb 2011 05:01:47 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=gmail.com; s=gamma;
        h=domainkey-signature:message-id:date:from:user-agent:mime-version:to
         :cc:subject:references:in-reply-to:content-type
         :content-transfer-encoding;
        bh=AbxlHNh3L+hBj6Vij/+GRK5xyYUXmvKoB1QZLa2ZBj0=;
        b=b/GQO7FpiFoh6WrR9d9qEW2Q1ZOK0YtYzl/fLoXZS49QbuYiuExhWkohPnHsdH/n7s
         liu8crpx1n3Ajna/7GX1mHBP6V4lfhH+NyF0Rmw3w+fx154lFiY9dbyPX7H9MZNdW60a
         8TmPRR356gmV+7bijgKwyMN1FRVMPNV0Zg0i8=
DomainKey-Signature: a=rsa-sha1; c=nofws;
        d=gmail.com; s=gamma;
        h=message-id:date:from:user-agent:mime-version:to:cc:subject
         :references:in-reply-to:content-type:content-transfer-encoding;
        b=C+hWB2Aof37xOLi8SWuN+D3QsDtf/f4yCxcLrNGhRYytyr/7CUmq/rS7PpgnfvBVBr
         yaKwVZXs7QRxIWbPnzmV38e1K+eUwZ+dd9XuEFN1dnXd5KJVv4CjWr2N84NIHx/NvOBL
         7QYK5+DuuRaccybcS4xWMNK8mujh9ebSBXTgM=
Received: by 10.223.87.1 with SMTP id u1mr4464553fal.112.1297688507260;
        Mon, 14 Feb 2011 05:01:47 -0800 (PST)
Received: from [192.168.0.101] (eab95-4-88-175-177-37.fbx.proxad.net [88.175.177.37])
        by mx.google.com with ESMTPS id y3sm1031898fai.38.2011.02.14.05.01.45
        (version=SSLv3 cipher=OTHER);
        Mon, 14 Feb 2011 05:01:46 -0800 (PST)
User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.16) Gecko/20101226 Icedove/3.0.11
In-Reply-To: <20110214122313.GA10062@albatros>
Sender: netdev-owner@vger.kernel.org
Precedence: bulk
List-ID: <netdev.vger.kernel.org>
X-Mailing-List: netdev@vger.kernel.org
Archived-At: <http://permalink.gmane.org/gmane.linux.kernel/1099723>

Le 14/02/2011 13:23, Vasiliy Kulikov a =E9crit :
> Hi Nicolas,

Hi Vasiliy,

> On Mon, Feb 14, 2011 at 13:16 +0100, Nicolas de Peslo=FCan wrote:
>>> -	BUG_ON(strlen(name)>=3D sizeof(dev->name));
>>> +	if (strnlen(name, sizeof(dev->name))>=3D sizeof(dev->name)) {
>
> Ehh...  Space after ")" is needed :)

:-D

>> "size_t strnlen(const char *s, size_t maxlen) : The strnlen()
>> function returns strlen(s), if that is less than maxlen, or maxlen
>> if there is no '\0' character among the first maxlen characters
>> pointed to by s."
>>
>> How can strnlen(name, sizeof(dev->name)) be greater than sizeof(dev-=
>name)?
>>
>> Shouldn't it be "if (strnlen(name, sizeof(dev->name)) =3D=3D sizeof(=
dev->name))" instead?
>
> Not a big deal, but MO it's better to guard from everything that
> is not a good input by negating the check.  strnlen()<  sizeof() is O=
K,
> strnlen()>=3D sizeof() is bad.  Is "=3D=3D" more preferable for net/ =
coding style?

Agreed, both cannot cause any troubles. =3D=3D is supposed to be better=
 from the API point of view, but=20
 >=3D is probably more readable.

	Nicolas.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html