Re: [Qemu-devel] [PATCH] vhost-scsi: prevent using uninitialized vqs

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Oct 23, 2018 at 01:49:16AM +0200, Philippe Mathieu-Daudé wrote:
> On 22/10/18 4:17, yuchenlin via Qemu-devel wrote:
> > Ping?
> > 
> > On 2018-10-12 17:07, yuchenlin@synology.com wrote:
> > > From: yuchenlin <yuchenlin@synology.com>
> > > 
> > > There are 3 virtqueues (ctrl, event and cmd) for virtio scsi device,
> > > but seabios will only set the physical address for the 3rd one (cmd).
> > > Then in vhost_virtqueue_start(), virtio_queue_get_desc_addr()
> > > will be 0 for ctrl and event vq.
> > > 
> > > In this case, ctrl and event vq are not initialized.
> > > vhost_verify_ring_mappings may use uninitialized vhost_virtqueue
> > > such that vhost_verify_ring_part_mapping returns ENOMEM.
> > > 
> > > When encountered this problem, we got the following logs:
> > > 
> > >     qemu-system-x86_64: Unable to map available ring for ring 0
> > >     qemu-system-x86_64: Verify ring failure on region 0
> > > 
> > > Signed-off-by: Forrest Liu <forrestl@synology.com>
> > > Signed-off-by: yuchenlin <yuchenlin@synology.com>
> 
> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

Thanks I will queue this.

> > > ---
> > >  hw/scsi/vhost-scsi.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/hw/scsi/vhost-scsi.c b/hw/scsi/vhost-scsi.c
> > > index becf550085..7f21b4f9d6 100644
> > > --- a/hw/scsi/vhost-scsi.c
> > > +++ b/hw/scsi/vhost-scsi.c
> > > @@ -183,7 +183,7 @@ static void vhost_scsi_realize(DeviceState *dev,
> > > Error **errp)
> > >      }
> > > 
> > >      vsc->dev.nvqs = VHOST_SCSI_VQ_NUM_FIXED + vs->conf.num_queues;
> > > -    vsc->dev.vqs = g_new(struct vhost_virtqueue, vsc->dev.nvqs);
> > > +    vsc->dev.vqs = g_new0(struct vhost_virtqueue, vsc->dev.nvqs);
> > >      vsc->dev.vq_index = 0;
> > >      vsc->dev.backend_features = 0;
> > 
> >