From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id 598CCA04B4; Tue, 19 Nov 2019 14:37:13 +0100 (CET) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 0F711235; Tue, 19 Nov 2019 14:37:12 +0100 (CET) Received: from mga06.intel.com (mga06.intel.com [134.134.136.31]) by dpdk.org (Postfix) with ESMTP id 4FA431F5; Tue, 19 Nov 2019 14:37:10 +0100 (CET) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 19 Nov 2019 05:37:09 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.68,324,1569308400"; d="scan'208";a="209420271" Received: from fyigit-mobl.ger.corp.intel.com (HELO [10.237.221.96]) ([10.237.221.96]) by orsmga006.jf.intel.com with ESMTP; 19 Nov 2019 05:37:07 -0800 From: Ferruh Yigit To: Andrew Rybchenko , Thomas Monjalon Cc: dev@dpdk.org, stable@dpdk.org References: <1574151770-25925-1-git-send-email-arybchenko@solarflare.com> <92cd3fb9-ae97-37cc-79ec-8b01e341504a@intel.com> <34e94334-931f-cd89-dc76-ce3a73f34b1a@solarflare.com> Openpgp: preference=signencrypt Autocrypt: addr=ferruh.yigit@intel.com; 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charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Subject: Re: [dpdk-dev] [dpdk-stable] [PATCH] ethdev: avoid undefined behaviour on configuration copying X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 11/19/2019 1:19 PM, Ferruh Yigit wrote: > On 11/19/2019 12:36 PM, Andrew Rybchenko wrote: >> On 11/19/19 3:24 PM, Ferruh Yigit wrote: >>> On 11/19/2019 8:22 AM, Andrew Rybchenko wrote: >>>> memcpy() source and destination areas must not overlap and equal >>>> pointers is the case which is really met, so handle it. >>> Agree providing same config as input can cause problem with current >>> implementation, but it is the limitation of the memcpy, the API doesn't request >>> this. >>> >>> We can fix as you suggested, in this case we should document this in API >>> documentation I think, >> >> Basically the patch solves it and there is nothing to document. >> If pointers are equal there is nothing to do, no copying required. > > You are right, scratch my comment. I overlooked as just overlapping memory issue. > >> >>> we can also solve this by updating the implementation to let this, using an >>> interim buffer in the simplest measure, not sure which one is better. >> >> I don't think that interim buffer is required, 'if' perfectly does the job. >> >>> Any practical reason to prevent this other than 'memcpy' limitation? >> >> Nothing except application should not play with dev->data, > > +1. > Bonding PMD though not exactly an application, not sure to let or not it to > update 'dev->data' > >> but I'm not sure if it is the right place to forbid it. >> >> Alternative solution is to fix bonding and return error if dev_conf is >> equal to &dev->data->dev_conf since usecase is unclear and callers >> should not use dev->data. >> >>>> Fixes: 68b931bff287 ("ethdev: eliminate interim variable") >>>> Cc: stable@dpdk.org >>>> >>>> Signed-off-by: Andrew Rybchenko >>>> --- >>>> slave_configure() in drivers/net/bonding calls rte_eth_dev_configure() >>>> with &slave_eth_dev->data->dev_conf. >>>> >>>> Alternative solution is to fix bonding and return error if dev_conf is >>>> equal to &dev->data->dev_conf since usecase is unclear and callers >>>> should not use dev->data. Right now each application should have a copy of each port config in application, and as we discussed before there is a chance that the application copy and the PMD copy can diverge here or there. What do you think having an API to get a copy/clone of the config from the PMD, later we can introduce the check you mentioned above, use case becomes: - Get the config from PMD - Update it - Configure PMD back with it This can prevent both application keeping copy and application updating config directly. Does it make sense? >>>> >>>> lib/librte_ethdev/rte_ethdev.c | 4 +++- >>>> 1 file changed, 3 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c >>>> index 8f48e8d659..8d2ce31a81 100644 >>>> --- a/lib/librte_ethdev/rte_ethdev.c >>>> +++ b/lib/librte_ethdev/rte_ethdev.c >>>> @@ -1245,7 +1245,9 @@ rte_eth_dev_configure(uint16_t port_id, uint16_t nb_rx_q, uint16_t nb_tx_q, >>>> * Copy the dev_conf parameter into the dev structure. >>>> * rte_eth_dev_info_get() requires dev_conf, copy it before dev_info get >>>> */ >>>> - memcpy(&dev->data->dev_conf, dev_conf, sizeof(dev->data->dev_conf)); >>>> + if (dev_conf != &dev->data->dev_conf) >>>> + memcpy(&dev->data->dev_conf, dev_conf, >>>> + sizeof(dev->data->dev_conf)); >>>> >>>> ret = rte_eth_dev_info_get(port_id, &dev_info); >>>> if (ret != 0) >>>> >> >