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=-9.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable 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 0548CC433E8 for ; Mon, 27 Jul 2020 10:31:32 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C1A392075A for ; Mon, 27 Jul 2020 10:31:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="LECjzwFA" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C1A392075A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:58032 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1k00Pr-0002oe-2x for qemu-devel@archiver.kernel.org; Mon, 27 Jul 2020 06:31:31 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:34532) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1k00LJ-0003bf-B1 for qemu-devel@nongnu.org; Mon, 27 Jul 2020 06:26:49 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:30824 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1k00LH-000671-Mk for qemu-devel@nongnu.org; Mon, 27 Jul 2020 06:26:49 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1595845606; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=7ygbq+txfC7KfLip4hu8EuUSnXN4O/uzF5z5V9+UkYk=; b=LECjzwFA3mTlzH5w6EUgsRiCpzhE8OplNNgjfWWSe/C5C/hdMnLLfNeCcPqKmJEBtnh187 TwCRqEuZ47OvLlVJO+R1NZsY0PX9ufEb38qJDCcVlkgUU0/mIikoL7ORTu+C579d/Zws0m 9XHAhIZK1leJV0APKFW2T0vDIUwIfD4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-440-tfkRWJzHMuWx9yZCuuBquQ-1; Mon, 27 Jul 2020 06:26:44 -0400 X-MC-Unique: tfkRWJzHMuWx9yZCuuBquQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1F996100CCC1 for ; Mon, 27 Jul 2020 10:26:44 +0000 (UTC) Received: from [10.72.12.200] (ovpn-12-200.pek2.redhat.com [10.72.12.200]) by smtp.corp.redhat.com (Postfix) with ESMTP id A7D3069328; Mon, 27 Jul 2020 10:26:39 +0000 (UTC) Subject: Re: [PATCH] virtio-net: check the existence of peer before accesing its config To: "Michael S. Tsirkin" , Cornelia Huck References: <20200727074328.2279-1-jasowang@redhat.com> <20200727053954-mutt-send-email-mst@kernel.org> <20200727115322.4e7fe1aa.cohuck@redhat.com> <20200727061112-mutt-send-email-mst@kernel.org> From: Jason Wang Message-ID: <0cad868a-7f64-47e0-f4bf-014a5fc1bcf6@redhat.com> Date: Mon, 27 Jul 2020 18:26:37 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200727061112-mutt-send-email-mst@kernel.org> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=205.139.110.120; envelope-from=jasowang@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/27 01:44:14 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -40 X-Spam_score: -4.1 X-Spam_bar: ---- X-Spam_report: (-4.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org, Cindy Lu Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 2020/7/27 下午6:13, Michael S. Tsirkin wrote: > On Mon, Jul 27, 2020 at 11:53:22AM +0200, Cornelia Huck wrote: >> On Mon, 27 Jul 2020 05:41:17 -0400 >> "Michael S. Tsirkin" wrote: >> >>> On Mon, Jul 27, 2020 at 03:43:28PM +0800, Jason Wang wrote: >>>> We try to get config from peer unconditionally which may lead NULL >>>> pointer dereference. Add a check before trying to access the config. >>>> >>>> Fixes: 108a64818e69b ("vhost-vdpa: introduce vhost-vdpa backend") >>>> Cc: Cindy Lu >>>> Tested-by: Cornelia Huck >>>> Signed-off-by: Jason Wang >>> I am a bit lost here. Isn't this invoked >>> when guest attempts to read the config? >>> With no peer, what do we return to guest? >> Same as with a non-vdpa peer? It's the dereference that needs to be >> guarded. > So vdpa has a GET_CONFIG ioctl which to me hints that a peer needs to be > notified on get config calls. > If we return config from qemu memory here, then I guess we > need to call GET_CONFIG on connect and validate it - > does this make sense? > > Cindy, Jason? For "connect" you meant connecting virtio-net to its peer (vDPA)? AFAIK, if we start with no peer, there's no way to set a peer afterwards. Thanks > >>> A code comment might be helpful here. >>> >>>> --- >>>> hw/net/virtio-net.c | 22 +++++++++++----------- >>>> 1 file changed, 11 insertions(+), 11 deletions(-)