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=-12.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,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 13533C433DF for ; Mon, 27 Jul 2020 10:25:08 +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 CDD5D2075A for ; Mon, 27 Jul 2020 10:25:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="QnwPMr8V" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CDD5D2075A 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]:34198 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1k00Je-0000Av-N2 for qemu-devel@archiver.kernel.org; Mon, 27 Jul 2020 06:25:06 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60044) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1k00H4-0005bt-N4 for qemu-devel@nongnu.org; Mon, 27 Jul 2020 06:22:26 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:24030 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 1k00H0-0004jC-3U for qemu-devel@nongnu.org; Mon, 27 Jul 2020 06:22:26 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1595845341; 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=AXUoc73tFVeWY96IQhCmu3WbzbPbhMePM1FSz1Ifw2Q=; b=QnwPMr8VVzMB2q7lROlfOltDiLwXpjTXD145bSfbLmKTEku4gAIgrMq5DA7H9NZAdmNisH ezYS/jKxbpB5ltQTxYD1BSEO0UwHPcyq3p9+TntCDTw08B5ypWuMqyLU6KFqLbeE8QYQtG x1gUNPD+ngmoS4Go983Tt1eHJ2jqxNg= 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-43-LVlLX7A8NUa7xR7h3JflOA-1; Mon, 27 Jul 2020 06:22:19 -0400 X-MC-Unique: LVlLX7A8NUa7xR7h3JflOA-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 44AE1101C8A9 for ; Mon, 27 Jul 2020 10:22:18 +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 A02CE5FC30; Mon, 27 Jul 2020 10:22:13 +0000 (UTC) Subject: Re: [PATCH] virtio-net: check the existence of peer before accesing its config To: "Michael S. Tsirkin" References: <20200727074328.2279-1-jasowang@redhat.com> <20200727053954-mutt-send-email-mst@kernel.org> <20200727061623-mutt-send-email-mst@kernel.org> From: Jason Wang Message-ID: Date: Mon, 27 Jul 2020 18:22:12 +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: <20200727061623-mutt-send-email-mst@kernel.org> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=jasowang@redhat.com 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=207.211.31.120; envelope-from=jasowang@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/27 00:16:29 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 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_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, 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: Cornelia Huck , 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6:17, Michael S. Tsirkin wrote: > On Mon, Jul 27, 2020 at 05:49:47PM +0800, Jason Wang wrote: >> On 2020/7/27 下午5:41, 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? >> >> With no peer, it just work as in the past (read from the qemu's own emulated >> config space). With a vDPA as its peer, it tries to read it from vhost-vDPA. > Are these scenarios where guest would sometimes get one and > sometimes another? E.g. does it happen on disconnect? > If yes that might become a problem ... For disconnecting yes, but I wonder if we need to care about that case anyway. Thanks > >>> A code comment might be helpful here. >> >> Does something like above help? >> >> Thanks >> >> >>>> --- >>>> hw/net/virtio-net.c | 22 +++++++++++----------- >>>> 1 file changed, 11 insertions(+), 11 deletions(-) >>>> >>>> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c >>>> index 4895af1cbe..935b9ef5c7 100644 >>>> --- a/hw/net/virtio-net.c >>>> +++ b/hw/net/virtio-net.c >>>> @@ -125,6 +125,7 @@ static void virtio_net_get_config(VirtIODevice *vdev, uint8_t *config) >>>> { >>>> VirtIONet *n = VIRTIO_NET(vdev); >>>> struct virtio_net_config netcfg; >>>> + NetClientState *nc = qemu_get_queue(n->nic); >>>> int ret = 0; >>>> memset(&netcfg, 0 , sizeof(struct virtio_net_config)); >>>> @@ -142,13 +143,12 @@ static void virtio_net_get_config(VirtIODevice *vdev, uint8_t *config) >>>> VIRTIO_NET_RSS_SUPPORTED_HASHES); >>>> memcpy(config, &netcfg, n->config_size); >>>> - NetClientState *nc = qemu_get_queue(n->nic); >>>> - if (nc->peer->info->type == NET_CLIENT_DRIVER_VHOST_VDPA) { >>>> + if (nc->peer && nc->peer->info->type == NET_CLIENT_DRIVER_VHOST_VDPA) { >>>> ret = vhost_net_get_config(get_vhost_net(nc->peer), (uint8_t *)&netcfg, >>>> - n->config_size); >>>> - if (ret != -1) { >>>> - memcpy(config, &netcfg, n->config_size); >>>> - } >>>> + n->config_size); >>>> + if (ret != -1) { >>>> + memcpy(config, &netcfg, n->config_size); >>>> + } >>>> } >>>> } >>>> @@ -156,6 +156,7 @@ static void virtio_net_set_config(VirtIODevice *vdev, const uint8_t *config) >>>> { >>>> VirtIONet *n = VIRTIO_NET(vdev); >>>> struct virtio_net_config netcfg = {}; >>>> + NetClientState *nc = qemu_get_queue(n->nic); >>>> memcpy(&netcfg, config, n->config_size); >>>> @@ -166,11 +167,10 @@ static void virtio_net_set_config(VirtIODevice *vdev, const uint8_t *config) >>>> qemu_format_nic_info_str(qemu_get_queue(n->nic), n->mac); >>>> } >>>> - NetClientState *nc = qemu_get_queue(n->nic); >>>> - if (nc->peer->info->type == NET_CLIENT_DRIVER_VHOST_VDPA) { >>>> - vhost_net_set_config(get_vhost_net(nc->peer), (uint8_t *)&netcfg, >>>> - 0, n->config_size, >>>> - VHOST_SET_CONFIG_TYPE_MASTER); >>>> + if (nc->peer && nc->peer->info->type == NET_CLIENT_DRIVER_VHOST_VDPA) { >>>> + vhost_net_set_config(get_vhost_net(nc->peer), >>>> + (uint8_t *)&netcfg, 0, n->config_size, >>>> + VHOST_SET_CONFIG_TYPE_MASTER); >>>> } >>>> } >>>> -- >>>> 2.20.1