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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 AE557C6787D for ; Mon, 8 Oct 2018 02:20:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 31160206B2 for ; Mon, 8 Oct 2018 02:20:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 31160206B2 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 S1726511AbeJHJ3y (ORCPT ); Mon, 8 Oct 2018 05:29:54 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40290 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725760AbeJHJ3y (ORCPT ); Mon, 8 Oct 2018 05:29:54 -0400 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 mx1.redhat.com (Postfix) with ESMTPS id C5BA943A21; Mon, 8 Oct 2018 02:20:35 +0000 (UTC) Received: from [10.72.12.136] (ovpn-12-136.pek2.redhat.com [10.72.12.136]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 780DB72307; Mon, 8 Oct 2018 02:20:26 +0000 (UTC) Subject: Re: [PATCH net V2] vhost-vsock: fix use after free To: "Michael S. Tsirkin" 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 References: <20180927122204.4188-1-jasowang@redhat.com> <20180927123539-mutt-send-email-mst@kernel.org> <588ed28b-7e4b-9dc8-92ce-d75692836c9e@redhat.com> <20180927194734-mutt-send-email-mst@kernel.org> From: Jason Wang Message-ID: <9ea5d616-8a78-b3c4-2a96-cbb6abb85c2c@redhat.com> Date: Mon, 8 Oct 2018 10:20:24 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180927194734-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Mon, 08 Oct 2018 02:20:35 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018年09月28日 07:50, Michael S. Tsirkin wrote: > On Fri, Sep 28, 2018 at 07:37:37AM +0800, Jason Wang wrote: >> >> On 2018年09月28日 01:04, Michael S. Tsirkin wrote: >>> 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? >> For net/stable, probably yes. >> >>> A global lock on a data path >>> operation? >> It's already there, > &vhost_vsock_lock? were is it takes on data path? Ok, but the current code use list which means a global lock is needed anyway here. > >> and the patch only increase the critical section. >> >>> 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 ... >>> >> Stefan has acked the pacth, so I think it's ok? We can do optimization for >> -next on top. >> >> Thanks > > Well on high SMP serializing can drop performance as much as x100 so I'm > not sure it's appropriate - seems to fix a bug but can introduce a > regression. Let's see how does a proper fix look first? > It looks to me hlist + RCU is better. But I'm not sure it's suitable for -net/-stable. Thanks