Re: [dpdk-dev] [PATCH v3 2/7] vhost: make gpa to hpa failure an error

[Tiwei Bie <tiwei.bie@intel.com>]

On Wed, Jun 27, 2018 at 04:49:54PM +0200, Maxime Coquelin wrote:
> CVE-2018-1059 fix makes sure gpa contiguous memory is
> also contiguous in hva space. Incidentally, it also makes
> sure it is contiguous in hpa space.
> 
> So we can simplify the code by making gpa contiguous memory
> discontiguous in hpa space an error.

Does it mean that when guest virtio driver using
gpa contiguous but hpa discontiguous memory, vhost
won't be able to process the corresponding desc?
And in this case, should vhost skip this desc?

Best regards,
Tiwei Bie

> 
> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> ---
>  lib/librte_vhost/virtio_net.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
> index 7e70a927f..ec4bcc400 100644
> --- a/lib/librte_vhost/virtio_net.c
> +++ b/lib/librte_vhost/virtio_net.c
> @@ -884,13 +884,13 @@ copy_desc_to_mbuf(struct virtio_net *dev, struct vhost_virtqueue *vq,
>  
>  		cpy_len = RTE_MIN(desc_chunck_len, mbuf_avail);
>  
> -		/*
> -		 * A desc buf might across two host physical pages that are
> -		 * not continuous. In such case (gpa_to_hpa returns 0), data
> -		 * will be copied even though zero copy is enabled.
> -		 */
> -		if (unlikely(dev->dequeue_zero_copy && (hpa = gpa_to_hpa(dev,
> -					desc_gaddr + desc_offset, cpy_len)))) {
> +		if (unlikely(dev->dequeue_zero_copy)) {
> +			hpa = gpa_to_hpa(dev,
> +					desc_gaddr + desc_offset, cpy_len);
> +			if (unlikely(!hpa)) {
> +				error = -1;
> +				goto out;
> +			}
>  			cur->data_len = cpy_len;
>  			cur->data_off = 0;
>  			cur->buf_addr = (void *)(uintptr_t)(desc_addr
> -- 
> 2.14.4
>