From mboxrd@z Thu Jan  1 00:00:00 1970
From: =?UTF-8?Q?Simon_K=c3=a5gstr=c3=b6m?= <simon.kagstrom@netinsight.net>
Subject: Re: Unsafe array accesses in rte_sched.c
Date: Fri, 16 Oct 2015 15:50:55 +0200
Message-ID: <562100BF.9010107@netinsight.net>
References: <5620BA12.9060702@netinsight.net>
 <3EB4FA525960D640B5BDFFD6A3D89126478F0C50@IRSMSX108.ger.corp.intel.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
To: "Dumitrescu, Cristian" <cristian.dumitrescu@intel.com>,
 "dev@dpdk.org" <dev@dpdk.org>
Return-path: <dev-bounces@dpdk.org>
Received: from ernst.netinsight.se (ernst.netinsight.se [194.16.221.21])
 by dpdk.org (Postfix) with SMTP id CB7DE8E5B
 for <dev@dpdk.org>; Fri, 16 Oct 2015 15:50:59 +0200 (CEST)
In-Reply-To: <3EB4FA525960D640B5BDFFD6A3D89126478F0C50@IRSMSX108.ger.corp.intel.com>
List-Id: patches and discussions about DPDK <dev.dpdk.org>
List-Unsubscribe: <http://dpdk.org/ml/options/dev>,
 <mailto:dev-request@dpdk.org?subject=unsubscribe>
List-Archive: <http://dpdk.org/ml/archives/dev/>
List-Post: <mailto:dev@dpdk.org>
List-Help: <mailto:dev-request@dpdk.org?subject=help>
List-Subscribe: <http://dpdk.org/ml/listinfo/dev>,
 <mailto:dev-request@dpdk.org?subject=subscribe>
Errors-To: dev-bounces@dpdk.org
Sender: "dev" <dev-bounces@dpdk.org>

On 2015-10-16 15:39, Dumitrescu, Cristian wrote:
>>         port->qsize_add[12] = port->qsize_add[11] + port->qsize[2];
>>         port->qsize_add[13] = port->qsize_add[12] + port->qsize[3];
>>         port->qsize_add[14] = port->qsize_add[13] + port->qsize[3];
>>         port->qsize_add[15] = port->qsize_add[14] + port->qsize[3];
>>
>>         port->qsize_sum = port->qsize_add[15] + port->qsize[3];
>>   }
>>
>> but port->qsize is actually defined as
>>
>>   uint16_t qsize[RTE_SCHED_TRAFFIC_CLASSES_PER_PIPE];
>>
> 
> Not sure what you see "unsafe" here: qsize is an array of 4 elements, while qsize_add is a different array of 16 elements? Please explain.

Sorry, I should have been more explicit: What I mean that the code
should loop over RTE_SCHED_TRAFFIC_CLASSES_PER_PIPE instead of
hard-coding the numbers.

It certainly works with the current RTE_SCHED_TRAFFIC_CLASSES_PER_PIPE,
but it would be safer (and in my opinion more clear) if it would not
assume RTE_SCHED_TRAFFIC_CLASSES_PER_PIPE == 4.

// Simon