Re: [PATCH 1/1] vhost: Protect the virtqueue from being cleared whilst still in use

Lee Jones
2022-03-02T10:08:04Z

On Wed, 02 Mar 2022, Stefano Garzarella wrote:

> On Wed, Mar 02, 2022 at 07:54:21AM +0000, Lee Jones wrote:
> > vhost_vsock_handle_tx_kick() already holds the mutex during its call
> > to vhost_get_vq_desc(). All we have to do is take the same lock
> > during virtqueue clean-up and we mitigate the reported issues.
> >
> > Link: https://syzkaller.appspot.com/bug?extid=279432d30d825e63ba00
>
> This issue is similar to [1] that should be already fixed upstream by [2].
>
> However I think this patch would have prevented some issues, because
> vhost_vq_reset() sets vq->private to NULL, preventing the worker from
> running.
>
> Anyway I think that when we enter in vhost_dev_cleanup() the worker should
> be already stopped, so it shouldn't be necessary to take the mutex. But in
> order to prevent future issues maybe it's better to take them, so:

> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

Thanks for the analysis and the review Stefano.

--
Lee Jones [李琼斯]
Principal Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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