> -----Original Message-----
> From: Yuanhan Liu [mailto:yuanhan.liu at linux.intel.com]
> Sent: Wednesday, November 18, 2015 10:57 AM
> To: Rich Lane <rich.lane at bigswitch.com>
> Cc: dev at dpdk.org; Xie, Huawei <huawei.xie at intel.com>; Wang, Zhihong
> <zhihong.wang at intel.com>; Richardson, Bruce <bruce.richardson at intel.com>
> Subject: Re: [PATCH] vhost: avoid buffer overflow in update_secure_len
>
> On Tue, Nov 17, 2015 at 08:39:30AM -0800, Rich Lane wrote:
> >
> > I don't think that adding a SIGINT handler is the right solution,
> > though. The guest app could be killed with another signal (SIGKILL).
>
> Good point.
>
> > Worse, a malicious or
> > buggy guest could write to just that field. vhost should not crash no
> > matter what the guest writes into the virtqueues.
>
> Yeah, I agree with you: though we could fix this issue in the source side, we
> also
> should do some defend here.
>
Exactly, DPDK should be able to take care of both ends:
# Provide interface for resource cleanup
# Be prepared if the app doesn't shutdown properly
> How about following patch then?
>
> Note that the vec_id overflow check should be done before referencing it, but
> not after. Hence I moved it ahead.
>
> --yliu
>
> ---
> diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c
> index
> 9322ce6..08f5942 100644
> --- a/lib/librte_vhost/vhost_rxtx.c
> +++ b/lib/librte_vhost/vhost_rxtx.c
> @@ -132,6 +132,8 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
>
> /* Get descriptor from available ring */
> desc = &vq->desc[head[packet_success]];
> + if (desc->len == 0)
> + break;
>
> buff = pkts[packet_success];
>
> @@ -153,6 +155,8 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
> /* Buffer address translation. */
> buff_addr = gpa_to_vva(dev, desc->addr);
> } else {
> + if (desc->len < vq->vhost_hlen)
> + break;
> vb_offset += vq->vhost_hlen;
> hdr = 1;
> }
> @@ -446,6 +450,9 @@ update_secure_len(struct vhost_virtqueue *vq, uint32_t
> id,
> uint32_t vec_id = *vec_idx;
>
> do {
> + if (vec_id >= BUF_VECTOR_MAX)
> + break;
> +
> next_desc = 0;
> len += vq->desc[idx].len;
> vq->buf_vec[vec_id].buf_addr = vq->desc[idx].addr; @@ -519,6
> +526,8 @@ virtio_dev_merge_rx(struct virtio_net *dev, uint16_t queue_id,
> goto merge_rx_exit;
> } else {
> update_secure_len(vq, res_cur_idx,
> &secure_len,
> &vec_idx);
> + if (secure_len == 0)
> + goto merge_rx_exit;
> res_cur_idx++;
> }
> } while (pkt_len > secure_len);
> @@ -631,6 +640,8 @@ rte_vhost_dequeue_burst(struct virtio_net *dev,
> uint16_t queue_id,
> uint8_t alloc_err = 0;
>
> desc = &vq->desc[head[entry_success]];
> + if (desc->len == 0)
> + break;
>
> /* Discard first buffer as it is the virtio header */
> if (desc->flags & VRING_DESC_F_NEXT) { @@ -638,6 +649,8 @@
> rte_vhost_dequeue_burst(struct virtio_net *dev, uint16_t queue_id,
> vb_offset = 0;
> vb_avail = desc->len;
> } else {
> + if (desc->len < vq->vhost_hlen)
> + break;
> vb_offset = vq->vhost_hlen;
> vb_avail = desc->len - vb_offset;
> }
