[dpdk-dev] [PATCH 5/6] vhost: fix possible dead loop in vector filling

[Tiwei Bie]

Fix a possible dead loop which may happen, e.g. when driver
created a loop in the desc list and lens in descs are zero.

Fixes: fd68b4739d2c ("vhost: use buffer vectors in dequeue path")
Fixes: 2f3225a7d69b ("vhost: add vector filling support for packed ring")
Cc: sta...@dpdk.org

Signed-off-by: Tiwei Bie <tiwei....@intel.com>
---
 lib/librte_vhost/virtio_net.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
index d64c355b9..0893a1d04 100644
--- a/lib/librte_vhost/virtio_net.c
+++ b/lib/librte_vhost/virtio_net.c
@@ -309,6 +309,7 @@ fill_vec_buf_split(struct virtio_net *dev, struct 
vhost_virtqueue *vq,
        uint16_t vec_id = *vec_idx;
        uint32_t len    = 0;
        uint64_t dlen;
+       uint32_t nr_descs = vq->size;
        struct vring_desc *descs = vq->desc;
        struct vring_desc *idesc = NULL;
 
@@ -319,6 +320,10 @@ fill_vec_buf_split(struct virtio_net *dev, struct 
vhost_virtqueue *vq,
 
        if (vq->desc[idx].flags & VRING_DESC_F_INDIRECT) {
                dlen = vq->desc[idx].len;
+               nr_descs = dlen / sizeof(struct vring_desc);
+               if (unlikely(nr_descs > vq->size))
+                       return -1;
+
                descs = (struct vring_desc *)(uintptr_t)
                        vhost_iova_to_vva(dev, vq, vq->desc[idx].addr,
                                                &dlen,
@@ -348,6 +353,11 @@ fill_vec_buf_split(struct virtio_net *dev, struct 
vhost_virtqueue *vq,
                        return -1;
                }
 
+               if (unlikely(nr_descs-- == 0)) {
+                       free_ind_table(idesc);
+                       return -1;
+               }
+
                len += descs[idx].len;
 
                if (unlikely(map_one_desc(dev, vq, buf_vec, &vec_id,
@@ -510,6 +520,9 @@ fill_vec_buf_packed(struct virtio_net *dev, struct 
vhost_virtqueue *vq,
                if (unlikely(vec_id >= BUF_VECTOR_MAX))
                        return -1;
 
+               if (unlikely(*desc_count >= vq->size))
+                       return -1;
+
                *desc_count += 1;
                *buf_id = descs[avail_idx].id;
 
-- 
2.17.1