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=-17.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 1966CC433DB for ; Mon, 8 Feb 2021 04:15:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CD13964E60 for ; Mon, 8 Feb 2021 04:15:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229703AbhBHEPJ (ORCPT ); Sun, 7 Feb 2021 23:15:09 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:58659 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229669AbhBHEPG (ORCPT ); Sun, 7 Feb 2021 23:15:06 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612757618; 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=OwbGbSWL1LBJv8uhMlfeoPlfAVlcGee31SXrkqRKFhU=; b=cv9sH2uH5lFecs9zfWEPTsU6gEbRlxhOjMvgLKkv9LX2Bd4OpPKAjqywD4oB/tnsC/WxCz G6OPnMMv+sdtpmtIWtYrNXeKm76WjnOkVnMzlYMUV4FlISi12pT07oy1Qe0IiZEM4jjhKh 58P7LXDdGFuYtO1VfLES327ieNZs5WU= 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-432-Ncn5d9ULMziacd2DWrxyRg-1; Sun, 07 Feb 2021 23:13:35 -0500 X-MC-Unique: Ncn5d9ULMziacd2DWrxyRg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id CC93A427C1; Mon, 8 Feb 2021 04:13:33 +0000 (UTC) Received: from [10.72.13.185] (ovpn-13-185.pek2.redhat.com [10.72.13.185]) by smtp.corp.redhat.com (Postfix) with ESMTP id 97DF262A22; Mon, 8 Feb 2021 04:13:24 +0000 (UTC) Subject: Re: [PATCH v3 09/13] vhost/vdpa: remove vhost_vdpa_config_validate() To: Stefano Garzarella , "Michael S. Tsirkin" Cc: virtualization@lists.linux-foundation.org, Xie Yongji , kvm@vger.kernel.org, Laurent Vivier , Stefan Hajnoczi , Max Gurtovoy , linux-kernel@vger.kernel.org References: <20210204172230.85853-1-sgarzare@redhat.com> <20210204172230.85853-10-sgarzare@redhat.com> <6919d2d4-cc8e-2b67-2385-35803de5e38b@redhat.com> <20210205091651.xfcdyuvwwzew2ufo@steredhat> <20210205083108-mutt-send-email-mst@kernel.org> <20210205141707.clbckauxnrzd7nmv@steredhat> From: Jason Wang Message-ID: Date: Mon, 8 Feb 2021 12:13:23 +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: <20210205141707.clbckauxnrzd7nmv@steredhat> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/2/5 下午10:17, Stefano Garzarella wrote: > On Fri, Feb 05, 2021 at 08:32:37AM -0500, Michael S. Tsirkin wrote: >> On Fri, Feb 05, 2021 at 10:16:51AM +0100, Stefano Garzarella wrote: >>> On Fri, Feb 05, 2021 at 11:27:32AM +0800, Jason Wang wrote: >>> > >>> > On 2021/2/5 上午1:22, Stefano Garzarella wrote: >>> > > get_config() and set_config() callbacks in the 'struct >>> vdpa_config_ops' >>> > > usually already validated the inputs. Also now they can return >>> an error, >>> > > so we don't need to validate them here anymore. >>> > > >>> > > Let's use the return value of these callbacks and return it in >>> case of >>> > > error in vhost_vdpa_get_config() and vhost_vdpa_set_config(). >>> > > >>> > > Originally-by: Xie Yongji >>> > > Signed-off-by: Stefano Garzarella >>> > > --- >>> > >  drivers/vhost/vdpa.c | 41 >>> +++++++++++++---------------------------- >>> > >  1 file changed, 13 insertions(+), 28 deletions(-) >>> > > >>> > > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c >>> > > index ef688c8c0e0e..d61e779000a8 100644 >>> > > --- a/drivers/vhost/vdpa.c >>> > > +++ b/drivers/vhost/vdpa.c >>> > > @@ -185,51 +185,35 @@ static long vhost_vdpa_set_status(struct >>> vhost_vdpa *v, u8 __user *statusp) >>> > >      return 0; >>> > >  } >>> > > -static int vhost_vdpa_config_validate(struct vhost_vdpa *v, >>> > > -                      struct vhost_vdpa_config *c) >>> > > -{ >>> > > -    long size = 0; >>> > > - >>> > > -    switch (v->virtio_id) { >>> > > -    case VIRTIO_ID_NET: >>> > > -        size = sizeof(struct virtio_net_config); >>> > > -        break; >>> > > -    } >>> > > - >>> > > -    if (c->len == 0) >>> > > -        return -EINVAL; >>> > > - >>> > > -    if (c->len > size - c->off) >>> > > -        return -E2BIG; >>> > > - >>> > > -    return 0; >>> > > -} >>> > > - >>> > >  static long vhost_vdpa_get_config(struct vhost_vdpa *v, >>> > >                    struct vhost_vdpa_config __user *c) >>> > >  { >>> > >      struct vdpa_device *vdpa = v->vdpa; >>> > >      struct vhost_vdpa_config config; >>> > >      unsigned long size = offsetof(struct vhost_vdpa_config, buf); >>> > > +    long ret; >>> > >      u8 *buf; >>> > >      if (copy_from_user(&config, c, size)) >>> > >          return -EFAULT; >>> > > -    if (vhost_vdpa_config_validate(v, &config)) >>> > > +    if (config.len == 0) >>> > >          return -EINVAL; >>> > >      buf = kvzalloc(config.len, GFP_KERNEL); >>> > >>> > >>> > Then it means usersapce can allocate a very large memory. >>> >>> Good point. >>> >>> > >>> > Rethink about this, we should limit the size here (e.g PAGE_SIZE) or >>> > fetch the config size first (either through a config ops as you >>> > suggested or a variable in the vdpa device that is initialized during >>> > device creation). >>> >>> Maybe PAGE_SIZE is okay as a limit. >>> >>> If instead we want to fetch the config size, then better a config >>> ops in my >>> opinion, to avoid adding a new parameter to __vdpa_alloc_device(). >>> >>> I vote for PAGE_SIZE, but it isn't a strong opinion. >>> >>> What do you and @Michael suggest? >>> >>> Thanks, >>> Stefano >> >> Devices know what the config size is. Just have them provide it. >> > > Okay, I'll add get_config_size() callback in vdpa_config_ops and I'll > leave vhost_vdpa_config_validate() that will use that callback instead > of 'virtio_id' to get the config size from the device. > > At this point I think I can remove the "vdpa: add return value to > get_config/set_config callbacks" patch and leave void return to > get_config/set_config callbacks. > > Does this make sense? > > Thanks, > Stefano Yes I think so. Thanks