linux-kernel - Re: [RFC PATCH 01/17] virtio_ring: Avoid reading unneeded used length

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 17 May 2021 11:11:59 +0200
From:   Johannes Berg <johannes@...solutions.net>
To:     Xie Yongji <xieyongji@...edance.com>, mst@...hat.com,
        jasowang@...hat.com, stefanha@...hat.com
Cc:     amit@...nel.org, arei.gonglei@...wei.com, airlied@...ux.ie,
        kraxel@...hat.com, dan.j.williams@...el.com, ohad@...ery.com,
        bjorn.andersson@...aro.org, david@...hat.com, vgoyal@...hat.com,
        miklos@...redi.hu, sgarzare@...hat.com,
        virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 01/17] virtio_ring: Avoid reading unneeded used
 length

On Mon, 2021-05-17 at 17:08 +0800, Xie Yongji wrote:
> If device driver doesn't need used length, it can pass a NULL
> len in virtqueue_get_buf()/virtqueue_get_buf_ctx().
> 

Well, actually, it can't right now?

You should probably rephrase this, saying something like

   Allow passing NULL to len in ... if the device driver doesn't need
   the length, and don't read it in that case.

or so?

>  Then
> we can avoid reading and validating the len value in used
> ring entries.

Not sure what that "validating" is about, I only see reading?

johannes