From: "Michael S. Tsirkin" <mst@redhat.com>
To: Jason Wang <jasowang@redhat.com>
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
Subject: Re: [PATCH net V2] vhost-vsock: fix use after free
Date: Thu, 27 Sep 2018 19:50:24 -0400 [thread overview]
Message-ID: <20180927194734-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <588ed28b-7e4b-9dc8-92ce-d75692836c9e@redhat.com>
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<stefanha@redhat.com>
> > > Signed-off-by: Jason Wang<jasowang@redhat.com>
> > 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?
> 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?
--
MST
next prev parent reply other threads:[~2018-09-27 23:50 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-27 12:22 [PATCH net V2] vhost-vsock: fix use after free Jason Wang
2018-09-27 15:33 ` Stefan Hajnoczi
2018-09-27 17:04 ` Michael S. Tsirkin
2018-09-27 23:37 ` Jason Wang
2018-09-27 23:50 ` Michael S. Tsirkin [this message]
2018-10-08 2:20 ` Jason Wang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180927194734-mutt-send-email-mst@kernel.org \
--to=mst@redhat.com \
--cc=jasowang@redhat.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=sergei.shtylyov@cogentembedded.com \
--cc=stefanha@redhat.com \
--cc=virtualization@lists.linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).