Commit message: vhost: fix translated address not checked

Malicious guest can construct desc with invalid address and zero buffer
length. That will request vhost to check both translated address and
translated data length. This patch will add missed address check.

CVE-2020-10725
Fixes: 75ed51697820 ("vhost: add packed ring batch dequeue")
Fixes: ef861692c398 ("vhost: add packed ring batch enqueue")
Cc: stable@dpdk.org

Signed-off-by: Marvin Liu <yong.liu@intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
CVE: CVE-2020-10725
CWE: CWE-665
Vulnerability description: A flaw was found in DPDK version 19.11 and above that allows a malicious guest to cause a segmentation fault of the vhost-user backend application running on the host, which could result in a loss of connectivity for the other guests running on that host. This is caused by a missing validity check of the descriptor address in the function `virtio_dev_rx_batch_packed()`.

Project: dpdk
File: virtio_net.c

virtio_dev_rx_batch_packed(struct virtio_net *dev,
			   struct vhost_virtqueue *vq,
			   struct rte_mbuf **pkts)
{
	bool wrap_counter = vq->avail_wrap_counter;
	struct vring_packed_desc *descs = vq->desc_packed;
	uint16_t avail_idx = vq->last_avail_idx;
	uint64_t desc_addrs[PACKED_BATCH_SIZE];
	struct virtio_net_hdr_mrg_rxbuf *hdrs[PACKED_BATCH_SIZE];
	uint32_t buf_offset = dev->vhost_hlen;
	uint64_t lens[PACKED_BATCH_SIZE];
	uint16_t ids[PACKED_BATCH_SIZE];
	uint16_t i;

	if (unlikely(avail_idx & PACKED_BATCH_MASK))
		return -1;

	if (unlikely((avail_idx + PACKED_BATCH_SIZE) > vq->size))
		return -1;

	vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE) {
		if (unlikely(pkts[i]->next != NULL))
			return -1;
		if (unlikely(!desc_is_avail(&descs[avail_idx + i],
					    wrap_counter)))
			return -1;
	}

	rte_smp_rmb();

	vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE)
		lens[i] = descs[avail_idx + i].len;

	vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE) {
		if (unlikely(pkts[i]->pkt_len > (lens[i] - buf_offset)))
			return -1;
	}

	vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE)
		desc_addrs[i] = vhost_iova_to_vva(dev, vq,
						  descs[avail_idx + i].addr,
						  &lens[i],
						  VHOST_ACCESS_RW);

	vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE) {
		if (unlikely(lens[i] != descs[avail_idx + i].len))
			return -1;
	}

	vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE) {
		rte_prefetch0((void *)(uintptr_t)desc_addrs[i]);
		hdrs[i] = (struct virtio_net_hdr_mrg_rxbuf *)
					(uintptr_t)desc_addrs[i];
		lens[i] = pkts[i]->pkt_len + dev->vhost_hlen;
	}

	vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE)
		virtio_enqueue_offload(pkts[i], &hdrs[i]->hdr);

	vq_inc_last_avail_packed(vq, PACKED_BATCH_SIZE);

	vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE) {
		rte_memcpy((void *)(uintptr_t)(desc_addrs[i] + buf_offset),
			   rte_pktmbuf_mtod_offset(pkts[i], void *, 0),
			   pkts[i]->pkt_len);
	}

	vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE)
		vhost_log_cache_write_iova(dev, vq, descs[avail_idx + i].addr,
					   lens[i]);

	vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE)
		ids[i] = descs[avail_idx + i].id;

	vhost_flush_enqueue_batch_packed(dev, vq, lens, ids);

	return 0;
}