From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id ADE9DC4332B for ; Wed, 3 Mar 2021 22:57:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8B65F64EFD for ; Wed, 3 Mar 2021 22:57:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1449541AbhCCWwI (ORCPT ); Wed, 3 Mar 2021 17:52:08 -0500 Received: from mga17.intel.com ([192.55.52.151]:3026 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235921AbhCCQhG (ORCPT ); Wed, 3 Mar 2021 11:37:06 -0500 IronPort-SDR: 8d+yTfKVAXyAcR7jPBSU4BCbS1E17XnTE59WY3MTrt7cRRw/s6PnpIVsF1aklmvRAREl2qqveX gsoAHbUMjtcg== X-IronPort-AV: E=McAfee;i="6000,8403,9912"; a="167126992" X-IronPort-AV: E=Sophos;i="5.81,220,1610438400"; d="scan'208";a="167126992" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Mar 2021 08:33:20 -0800 IronPort-SDR: zvVoBXWCVPH7UasWm9ojZhJbOWpCUVfjlA0aYlqeeaJ5IvJVBWvlQwhR4j/JTpHY84KeTtcppc ahmigwhPHzeQ== X-IronPort-AV: E=Sophos;i="5.81,220,1610438400"; d="scan'208";a="407308383" Received: from jdibley-mobl1.ger.corp.intel.com (HELO btopel-mobl.ger.intel.com) ([10.252.61.121]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Mar 2021 08:33:17 -0800 Subject: Re: [PATCH bpf 3/3] libbpf: clear map_info before each bpf_obj_get_info_by_fd To: Maciej Fijalkowski , daniel@iogearbox.net, ast@kernel.org, bpf@vger.kernel.org Cc: magnus.karlsson@intel.com, john.fastabend@gmail.com References: <20210303155158.15953-1-maciej.fijalkowski@intel.com> <20210303155158.15953-4-maciej.fijalkowski@intel.com> From: =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= Message-ID: <9838f0ef-7430-e2b2-4146-5ec6c9c807bd@intel.com> Date: Wed, 3 Mar 2021 17:33:13 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <20210303155158.15953-4-maciej.fijalkowski@intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 2021-03-03 16:51, Maciej Fijalkowski wrote: > xsk_lookup_bpf_maps, based on prog_fd, looks whether current prog has a > reference to XSKMAP. BPF prog can include insns that work on various BPF > maps and this is covered by iterating through map_ids. > > The bpf_map_info that is passed to bpf_obj_get_info_by_fd for filling > needs to be cleared at each iteration, so that it doesn't contain any > outdated fields and that is currently missing in the function of > interest. > > To fix that, zero-init map_info via memset before each > bpf_obj_get_info_by_fd call. > > Also, since the area of this code is touched, in general strcmp is > considered harmful, so let's convert it to strncmp and provide the > length of the array name from current map_info. > > Last but not least, do s/continue/break/ once we have found the xsks_map > to terminate the search. > > Fixes: 5750902a6e9b ("libbpf: proper XSKMAP cleanup") > Signed-off-by: Maciej Fijalkowski > --- > tools/lib/bpf/xsk.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c > index ffbb588724d8..e56b2d76efc2 100644 > --- a/tools/lib/bpf/xsk.c > +++ b/tools/lib/bpf/xsk.c > @@ -610,15 +610,16 @@ static int xsk_lookup_bpf_maps(struct xsk_socket *xsk) > if (fd < 0) > continue; > > + memset(&map_info, 0, map_len); > err = bpf_obj_get_info_by_fd(fd, &map_info, &map_len); > if (err) { > close(fd); > continue; > } > > - if (!strcmp(map_info.name, "xsks_map")) { > + if (!strncmp(map_info.name, "xsks_map", strlen(map_info.name))) { This should be sizeof(map_info.name) and not strlen, otherwise it's kind of useless! :-P Björn > ctx->xsks_map_fd = fd; > - continue; > + break; > } > > close(fd); >