netdev - Re: [syzbot] [kvm?] [net?] [virt?] general protection fault in vhost_work

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: Tue, 30 May 2023 11:09:09 -0500
From: Mike Christie <michael.christie@...cle.com>
To: Stefano Garzarella <sgarzare@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>
Cc: syzbot <syzbot+d0d442c22fa8db45ff0e@...kaller.appspotmail.com>,
        jasowang@...hat.com, kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, syzkaller-bugs@...glegroups.com,
        virtualization@...ts.linux-foundation.org, stefanha@...hat.com
Subject: Re: [syzbot] [kvm?] [net?] [virt?] general protection fault in
 vhost_work_queue

On 5/30/23 11:00 AM, Stefano Garzarella wrote:
> I think it is partially related to commit 6e890c5d5021 ("vhost: use
> vhost_tasks for worker threads") and commit 1a5f8090c6de ("vhost: move
> worker thread fields to new struct"). Maybe that commits just
> highlighted the issue and it was already existing.

See my mail about the crash. Agree with your analysis about worker->vtsk
not being set yet. It's a bug from my commit where I should have not set
it so early or I should be checking for

if (dev->worker && worker->vtsk)

instead of 

if (dev->worker)

One question about the behavior before my commit though and what we want in
the end going forward. Before that patch we would just drop work if
vhost_work_queue was called before VHOST_SET_OWNER. Was that correct/expected?

The call to vhost_work_queue in vhost_vsock_start was only seeing the
works queued after VHOST_SET_OWNER. Did you want works queued before that?