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 DB943A04B4; Tue, 19 Nov 2019 14:19:26 +0100 (CET) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 2D0F427D; Tue, 19 Nov 2019 14:19:26 +0100 (CET) Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by dpdk.org (Postfix) with ESMTP id 76529237; Tue, 19 Nov 2019 14:19:24 +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 fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 19 Nov 2019 05:19:23 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.68,324,1569308400"; d="scan'208";a="209417384" 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 05:19:22 -0800 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> From: Ferruh Yigit 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] [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 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. >>> >>> 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) >>> >