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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 A70AFC04AB3 for ; Wed, 29 May 2019 03:22:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8A16D21019 for ; Wed, 29 May 2019 03:22:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726544AbfE2DWw (ORCPT ); Tue, 28 May 2019 23:22:52 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58200 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725856AbfE2DWw (ORCPT ); Tue, 28 May 2019 23:22:52 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D2D51308425C; Wed, 29 May 2019 03:22:51 +0000 (UTC) Received: from [10.72.12.48] (ovpn-12-48.pek2.redhat.com [10.72.12.48]) by smtp.corp.redhat.com (Postfix) with ESMTP id D46731972B; Wed, 29 May 2019 03:22:42 +0000 (UTC) Subject: Re: [PATCH 3/4] vsock/virtio: fix flush of works during the .remove() To: Stefano Garzarella , netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, Stefan Hajnoczi , "David S. Miller" , "Michael S . Tsirkin" References: <20190528105623.27983-1-sgarzare@redhat.com> <20190528105623.27983-4-sgarzare@redhat.com> From: Jason Wang Message-ID: <9ac9fc4b-5c39-2503-dfbb-660a7bdcfbfd@redhat.com> Date: Wed, 29 May 2019 11:22:40 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190528105623.27983-4-sgarzare@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.40]); Wed, 29 May 2019 03:22:51 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/5/28 下午6:56, Stefano Garzarella wrote: > We flush all pending works before to call vdev->config->reset(vdev), > but other works can be queued before the vdev->config->del_vqs(vdev), > so we add another flush after it, to avoid use after free. > > Suggested-by: Michael S. Tsirkin > Signed-off-by: Stefano Garzarella > --- > net/vmw_vsock/virtio_transport.c | 23 +++++++++++++++++------ > 1 file changed, 17 insertions(+), 6 deletions(-) > > diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c > index e694df10ab61..ad093ce96693 100644 > --- a/net/vmw_vsock/virtio_transport.c > +++ b/net/vmw_vsock/virtio_transport.c > @@ -660,6 +660,15 @@ static int virtio_vsock_probe(struct virtio_device *vdev) > return ret; > } > > +static void virtio_vsock_flush_works(struct virtio_vsock *vsock) > +{ > + flush_work(&vsock->loopback_work); > + flush_work(&vsock->rx_work); > + flush_work(&vsock->tx_work); > + flush_work(&vsock->event_work); > + flush_work(&vsock->send_pkt_work); > +} > + > static void virtio_vsock_remove(struct virtio_device *vdev) > { > struct virtio_vsock *vsock = vdev->priv; > @@ -668,12 +677,6 @@ static void virtio_vsock_remove(struct virtio_device *vdev) > mutex_lock(&the_virtio_vsock_mutex); > the_virtio_vsock = NULL; > > - flush_work(&vsock->loopback_work); > - flush_work(&vsock->rx_work); > - flush_work(&vsock->tx_work); > - flush_work(&vsock->event_work); > - flush_work(&vsock->send_pkt_work); > - > /* Reset all connected sockets when the device disappear */ > vsock_for_each_connected_socket(virtio_vsock_reset_sock); > > @@ -690,6 +693,9 @@ static void virtio_vsock_remove(struct virtio_device *vdev) > vsock->event_run = false; > mutex_unlock(&vsock->event_lock); > > + /* Flush all pending works */ > + virtio_vsock_flush_works(vsock); > + > /* Flush all device writes and interrupts, device will not use any > * more buffers. > */ > @@ -726,6 +732,11 @@ static void virtio_vsock_remove(struct virtio_device *vdev) > /* Delete virtqueues and flush outstanding callbacks if any */ > vdev->config->del_vqs(vdev); > > + /* Other works can be queued before 'config->del_vqs()', so we flush > + * all works before to free the vsock object to avoid use after free. > + */ > + virtio_vsock_flush_works(vsock); Some questions after a quick glance: 1) It looks to me that the work could be queued from the path of vsock_transport_cancel_pkt() . Is that synchronized here? 2) If we decide to flush after dev_vqs(), is tx_run/rx_run/event_run still needed? It looks to me we've already done except that we need flush rx_work in the end since send_pkt_work can requeue rx_work. Thanks > + > kfree(vsock); > mutex_unlock(&the_virtio_vsock_mutex); > }