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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 56C86C43382 for ; Thu, 27 Sep 2018 17:05:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1767421582 for ; Thu, 27 Sep 2018 17:05:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1767421582 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728706AbeI0XYe (ORCPT ); Thu, 27 Sep 2018 19:24:34 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41406 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727587AbeI0XYe (ORCPT ); Thu, 27 Sep 2018 19:24:34 -0400 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.24]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 723AF80F79; Thu, 27 Sep 2018 17:05:21 +0000 (UTC) Received: from redhat.com (ovpn-123-154.rdu2.redhat.com [10.10.123.154]) by smtp.corp.redhat.com (Postfix) with SMTP id 6572B30918A5; Thu, 27 Sep 2018 17:04:59 +0000 (UTC) Date: Thu, 27 Sep 2018 13:04:58 -0400 From: "Michael S. Tsirkin" To: Jason Wang Cc: stefanha@redhat.com, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, sergei.shtylyov@cogentembedded.com Subject: Re: [PATCH net V2] vhost-vsock: fix use after free Message-ID: <20180927123539-mutt-send-email-mst@kernel.org> References: <20180927122204.4188-1-jasowang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180927122204.4188-1-jasowang@redhat.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.24 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Thu, 27 Sep 2018 17:05:21 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 27, 2018 at 08:22:04PM +0800, Jason Wang wrote: > The access of vsock is not protected by vhost_vsock_lock. This may > lead to use after free since vhost_vsock_dev_release() may free the > pointer at the same time. > > Fix this by holding the lock during the access. > > Reported-by: syzbot+e3e074963495f92a89ed@syzkaller.appspotmail.com > Fixes: 16320f363ae1 ("vhost-vsock: add pkt cancel capability") > Fixes: 433fc58e6bf2 ("VSOCK: Introduce vhost_vsock.ko") > Cc: Stefan Hajnoczi > Signed-off-by: Jason Wang Wow is that really the best we can do? A global lock on a data path operation? Granted use after free is nasty but Stefan said he sees a way to fix it using a per socket refcount. He's on vacation until Oct 4 though ... > --- > - V2: fix typos > - The patch is needed for -stable. > --- > drivers/vhost/vsock.c | 26 +++++++++++++++++++------- > 1 file changed, 19 insertions(+), 7 deletions(-) > > diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c > index 34bc3ab40c6d..7d0b292867fd 100644 > --- a/drivers/vhost/vsock.c > +++ b/drivers/vhost/vsock.c > @@ -210,21 +210,27 @@ vhost_transport_send_pkt(struct virtio_vsock_pkt *pkt) > struct vhost_vsock *vsock; > int len = pkt->len; > > + spin_lock_bh(&vhost_vsock_lock); > + > /* Find the vhost_vsock according to guest context id */ > - vsock = vhost_vsock_get(le64_to_cpu(pkt->hdr.dst_cid)); > + vsock = __vhost_vsock_get(le64_to_cpu(pkt->hdr.dst_cid)); > if (!vsock) { > virtio_transport_free_pkt(pkt); > + spin_unlock_bh(&vhost_vsock_lock); > return -ENODEV; > } > > if (pkt->reply) > atomic_inc(&vsock->queued_replies); > > - spin_lock_bh(&vsock->send_pkt_list_lock); > + spin_lock(&vsock->send_pkt_list_lock); > list_add_tail(&pkt->list, &vsock->send_pkt_list); > - spin_unlock_bh(&vsock->send_pkt_list_lock); > + spin_unlock(&vsock->send_pkt_list_lock); > > vhost_work_queue(&vsock->dev, &vsock->send_pkt_work); > + > + spin_unlock_bh(&vhost_vsock_lock); > + > return len; > } > > @@ -236,18 +242,22 @@ vhost_transport_cancel_pkt(struct vsock_sock *vsk) > int cnt = 0; > LIST_HEAD(freeme); > > + spin_lock_bh(&vhost_vsock_lock); > + > /* Find the vhost_vsock according to guest context id */ > - vsock = vhost_vsock_get(vsk->remote_addr.svm_cid); > - if (!vsock) > + vsock = __vhost_vsock_get(vsk->remote_addr.svm_cid); > + if (!vsock) { > + spin_unlock_bh(&vhost_vsock_lock); > return -ENODEV; > + } > > - spin_lock_bh(&vsock->send_pkt_list_lock); > + spin_lock(&vsock->send_pkt_list_lock); > list_for_each_entry_safe(pkt, n, &vsock->send_pkt_list, list) { > if (pkt->vsk != vsk) > continue; > list_move(&pkt->list, &freeme); > } > - spin_unlock_bh(&vsock->send_pkt_list_lock); > + spin_unlock(&vsock->send_pkt_list_lock); > > list_for_each_entry_safe(pkt, n, &freeme, list) { > if (pkt->reply) > @@ -265,6 +275,8 @@ vhost_transport_cancel_pkt(struct vsock_sock *vsk) > vhost_poll_queue(&tx_vq->poll); > } > > + spin_unlock_bh(&vhost_vsock_lock); > + > return 0; > } > > -- > 2.17.1