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Date:   Mon, 24 Jul 2023 05:16:25 -0400
From:   "Michael S. Tsirkin" <mst@redhat.com>
To:     Dragos Tatulea <dtatulea@nvidia.com>
Cc:     "jasowang@redhat.com" <jasowang@redhat.com>,
        "virtualization@lists.linux-foundation.org" 
        <virtualization@lists.linux-foundation.org>,
        "linma@zju.edu.cn" <linma@zju.edu.cn>, Eli Cohen <elic@nvidia.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "xuanzhuo@linux.alibaba.com" <xuanzhuo@linux.alibaba.com>,
        Parav Pandit <parav@nvidia.com>
Subject: Re: [PATCH v1] vdpa: Complement vdpa_nl_policy for nlattr length
 check
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On Mon, Jul 24, 2023 at 08:38:04AM +0000, Dragos Tatulea wrote:
> 
> On Mon, 2023-07-24 at 15:11 +0800, Jason Wang wrote:
> > On Sun, Jul 23, 2023 at 6:02 PM Michael S. Tsirkin <mst@redhat.com> wrote:
> > > 
> > > On Sun, Jul 23, 2023 at 05:48:46PM +0800, Lin Ma wrote:
> > > > 
> > > > > Sure, that is another undergoing task I'm working on. If the nlattr is
> > > > > parsed with
> > > > > NL_VALIDATE_UNSPEC, any forgotten nlattr will be rejected, therefore
> > > > > (which is the default
> > > > > for modern nla_parse).
> > > > 
> > > > For the general netlink interface, the deciding flag should be
> > > > genl_ops.validate defined in
> > > > each ops. The default validate flag is strict, while the developer can
> > > > overwrite the flag
> > > > with GENL_DONT_VALIDATE_STRICT to ease the validation. That is to say,
> > > > safer code should
> > > > enforce NL_VALIDATE_STRICT by not overwriting the validate flag.
> > > > 
> > > > Regrads
> > > > Lin
> > > 
> > > 
> > > Oh I see.
> > > 
> > > It started here:
> > > 
> > > commit 33b347503f014ebf76257327cbc7001c6b721956
> > > Author: Parav Pandit <parav@nvidia.com>
> > > Date:   Tue Jan 5 12:32:00 2021 +0200
> > > 
> > >     vdpa: Define vdpa mgmt device, ops and a netlink interface
> > > 
> > > which did:
> > > 
> > > +               .validate = GENL_DONT_VALIDATE_STRICT |
> > > GENL_DONT_VALIDATE_DUMP,
> > > 
> > > 
> > > which was most likely just a copy paste from somewhere, right Parav?
> > > 
> > > and then everyone kept copying this around.
> > > 
> > > Parav, Eli can we drop these? There's a tiny chance of breaking something
> > > but I feel there aren't that many users outside mlx5 yet, so if you
> > > guys can test on mlx5 and confirm no breakage, I think we are good.
> > 
> > Adding Dragos.
> > 
> I will check. Just to make sure I understand correctly: you want me to drop the
> .validate flags all together in all vdpa ops and check, right?
> 
> Thanks,
> Dragos

yes - I suspect you will then need this patch to make things work.

-- 
MST