[dpdk-stable] [PATCH 1/3] vhost: fix split ring potential buffer overflow

Marvin Liu yong.liu at intel.com
Thu Mar 25 04:01:37 CET 2021


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: stable at dpdk.org

Signed-off-by: Marvin Liu <yong.liu at intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin at redhat.com>

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



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