In vhost datapath, descriptor's length are mostly used in two coherent
operations. First step is used for address translation, second step is
used for memory transaction from guest to host. But the iterval between
two steps will give a window for malicious guest, in which can change
descriptor length after vhost calcuated buffer size. Thus may lead to
buffer overflow in vhost side. This potential risk can be eliminated by
accessing the descriptor length once.
Fixes: 1be4ebb1c464 ("vhost: support indirect descriptor in mergeable Rx")
Cc: [email protected]
Signed-off-by: Marvin Liu <[email protected]>
Reviewed-by: Maxime Coquelin <[email protected]>
diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
index 583bf379c6..576a0a20c0 100644
--- a/lib/librte_vhost/virtio_net.c
+++ b/lib/librte_vhost/virtio_net.c
@@ -548,10 +548,11 @@ fill_vec_buf_split(struct virtio_net *dev, struct
vhost_virtqueue *vq,
return -1;
}
- len += descs[idx].len;
+ dlen = descs[idx].len;
+ len += dlen;
if (unlikely(map_one_desc(dev, vq, buf_vec, &vec_id,
- descs[idx].addr, descs[idx].len,
+ descs[idx].addr, dlen,
perm))) {
free_ind_table(idesc);
return -1;
--
2.17.1
