netdev - Re: [PATCH net-next v9] virtio/vsock: replace virtio_vsock_pkt with sk

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Date:   Thu, 22 Dec 2022 06:12:29 +0000
From:   Bobby Eshleman <bobbyeshleman@...il.com>
To:     Paolo Abeni <pabeni@...hat.com>
Cc:     Bobby Eshleman <bobby.eshleman@...edance.com>,
        Cong Wang <cong.wang@...edance.com>, kvm@...r.kernel.org,
        "Michael S. Tsirkin" <mst@...hat.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        Eric Dumazet <edumazet@...gle.com>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH net-next v9] virtio/vsock: replace virtio_vsock_pkt with
 sk_buff

On Tue, Jan 10, 2023 at 03:45:32PM +0100, Paolo Abeni wrote:
> On Tue, 2023-01-10 at 09:36 +0100, Paolo Abeni wrote:
> > On Sat, 2023-01-07 at 00:29 +0000, Bobby Eshleman wrote:
> > > This commit changes virtio/vsock to use sk_buff instead of
> > > virtio_vsock_pkt. Beyond better conforming to other net code, using
> > > sk_buff allows vsock to use sk_buff-dependent features in the future
> > > (such as sockmap) and improves throughput.
> > > 
> > > This patch introduces the following performance changes:
> > > 
> > > Tool/Config: uperf w/ 64 threads, SOCK_STREAM
> > > Test Runs: 5, mean of results
> > > Before: commit 95ec6bce2a0b ("Merge branch 'net-ipa-more-endpoints'")
> > > 
> > > Test: 64KB, g2h
> > > Before: 21.63 Gb/s
> > > After: 25.59 Gb/s (+18%)
> > > 
> > > Test: 16B, g2h
> > > Before: 11.86 Mb/s
> > > After: 17.41 Mb/s (+46%)
> > > 
> > > Test: 64KB, h2g
> > > Before: 2.15 Gb/s
> > > After: 3.6 Gb/s (+67%)
> > > 
> > > Test: 16B, h2g
> > > Before: 14.38 Mb/s
> > > After: 18.43 Mb/s (+28%)
> > > 
> > > Signed-off-by: Bobby Eshleman <bobby.eshleman@...edance.com>
> > > Reviewed-by: Stefano Garzarella <sgarzare@...hat.com>
> > > Acked-by: Paolo Abeni <pabeni@...hat.com>
> > > ---
> > > 
> > > Tested using vsock_test g2h and h2g.  I'm not sure if it is standard
> > > practice here to carry Acks and Reviews forward to future versions, but
> > > I'm doing that here to hopefully make life easier for maintainers.
> > > Please let me know if it is not standard practice.
> > 
> > As Jakub noted, there is no clear rule for tag passing across different
> > patch revisions.
> > 
> > Here, given the complexity of the patch and the not trivial list of
> > changes, I would have preferred you would have dropped my tag.
> > 
> > > Changes in v9:
> > > - check length in rx header
> > > - guard alloactor from small requests
> > > - squashed fix for v8 bug reported by syzbot:
> > >     syzbot+30b72abaa17c07fe39dd@...kaller.appspotmail.com
> > 
> > It's not clear to me what/where is the fix exactly, could you please
> > clarify?
> 
> Reading the syzkaller report, it looks like iov_length() in
> vhost_vsock_alloc_pkt() can not be trusted to carry a reasonable value.
> 
> As such, don't you additionally need to ensure/check that iov_length()
> is greater or equal to sizeof(virtio_vsock_hdr) ?

Yep, the check is in virtio_vsock_alloc_skb() (a good central point that
both vhost/virtio call into), returning NULL and allocating nothing if
the size is nonsense.

Thanks,
Bobby