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 14166C433DF for ; Mon, 27 Jul 2020 09:51:09 +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 D19CE20672 for ; Mon, 27 Jul 2020 09:51:08 +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="ZLqq1VAX" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D19CE20672 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]:35302 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jzzmm-0000ZW-65 for qemu-devel@archiver.kernel.org; Mon, 27 Jul 2020 05:51:08 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39576) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jzzlf-00085l-D9 for qemu-devel@nongnu.org; Mon, 27 Jul 2020 05:49:59 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:44166 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 1jzzld-0006Rs-OR for qemu-devel@nongnu.org; Mon, 27 Jul 2020 05:49:59 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1595843397; 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=COGym/nbml5D3yPiSuh3NU5NBGAzuqHHeWZXFQuOHEY=; b=ZLqq1VAXUTJHQ82KE2gg+7EKtwd+fA37+0dqekM7WUM81d2jA6aQHtfNDSPyR7paLLiRvG rzLlzjYpwy2DKJxqTzhoalij10TM8Gsd5JweZVpqF8FTcNDUC8nQ+tEwTsvTq/lu+DLSid ruuUz17Js+VqUDFFg99yxQrLJPM/Qkc= 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-44-GOHVvdy-P32vBw1Nh493uA-1; Mon, 27 Jul 2020 05:49:55 -0400 X-MC-Unique: GOHVvdy-P32vBw1Nh493uA-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 7CA59106B248 for ; Mon, 27 Jul 2020 09:49:54 +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 40DD85FC36; Mon, 27 Jul 2020 09:49:48 +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> From: Jason Wang Message-ID: Date: Mon, 27 Jul 2020 17:49:47 +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: <20200727053954-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=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: 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. > 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