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Date: Thu, 14 Oct 2021 10:32:32 +0800 From: Jason Wang <jasowang@...hat.com> To: "Michael S. Tsirkin" <mst@...hat.com> Cc: virtualization <virtualization@...ts.linux-foundation.org>, linux-kernel <linux-kernel@...r.kernel.org>, "Hetzelt, Felicitas" <f.hetzelt@...berlin.de>, "kaplan, david" <david.kaplan@....com>, Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>, Paolo Bonzini <pbonzini@...hat.com>, Stefan Hajnoczi <stefanha@...hat.com>, Stefano Garzarella <sgarzare@...hat.com> Subject: Re: [PATCH V2 01/12] virtio-blk: validate num_queues during probe On Wed, Oct 13, 2021 at 6:04 PM Michael S. Tsirkin <mst@...hat.com> wrote: > > On Tue, Oct 12, 2021 at 02:52:16PM +0800, Jason Wang wrote: > > If an untrusted device neogitates BLK_F_MQ but advertises a zero > > num_queues, the driver may end up trying to allocating zero size > > buffers where ZERO_SIZE_PTR is returned which may pass the checking > > against the NULL. This will lead unexpected results. > > > > Fixing this by using single queue if num_queues is zero. > > > > Cc: Paolo Bonzini <pbonzini@...hat.com> > > Cc: Stefan Hajnoczi <stefanha@...hat.com> > > Cc: Stefano Garzarella <sgarzare@...hat.com> > > Reviewed-by: Stefan Hajnoczi <stefanha@...hat.com> > > Signed-off-by: Jason Wang <jasowang@...hat.com> > > I'd rather fail probe so we don't need to support that. I think we should be consistent among all virtio drivers. E.g without this patch, we stick to 1 if virtio_create_feature() fail. Do we need to fix that? And we do something similar at least for the virtio-net and a lot of other places. /* We need at least 2 queue's */ if (err || max_queue_pairs < VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MIN || max_queue_pairs > VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MAX || !virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ)) max_queue_pairs = 1; Thanks > > > --- > > drivers/block/virtio_blk.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c > > index 9b3bd083b411..9deff01a38cb 100644 > > --- a/drivers/block/virtio_blk.c > > +++ b/drivers/block/virtio_blk.c > > @@ -495,7 +495,8 @@ static int init_vq(struct virtio_blk *vblk) > > err = virtio_cread_feature(vdev, VIRTIO_BLK_F_MQ, > > struct virtio_blk_config, num_queues, > > &num_vqs); > > - if (err) > > + /* We need at least one virtqueue */ > > + if (err || !num_vqs) > > num_vqs = 1; > > > > num_vqs = min_t(unsigned int, nr_cpu_ids, num_vqs); > > -- > > 2.25.1 >
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