From a436f53ebfeb5a76df1e2248db8064e9dab8e739 Mon Sep 17 00:00:00 2001
From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Date: Thu, 10 Mar 2016 12:32:46 +0800
Subject: [PATCH] vhost: avoid dead loop chain
If a malicious guest forges a dead loop chain, it could lead to a dead
loop of copying the desc buf to mbuf, which results to all mbuf being
exhausted.
Add a var nr_desc to avoid such case.
Suggested-by: Huawei Xie <huawei.xie@intel.com>
Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
---
lib/librte_vhost/vhost_rxtx.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c
index b0d0dff288..ca939d6601 100644
--- a/lib/librte_vhost/vhost_rxtx.c
+++ b/lib/librte_vhost/vhost_rxtx.c
@@ -745,6 +745,8 @@ copy_desc_to_mbuf(struct virtio_net *dev, struct vhost_virtqueue *vq,
uint32_t cpy_len;
struct rte_mbuf *cur = m, *prev = m;
struct virtio_net_hdr *hdr;
+ /* A counter to avoid desc dead loop chain */
+ uint32_t nr_desc = 1;
desc = &vq->desc[desc_idx];
if (unlikely(desc->len < vq->vhost_hlen))
@@ -763,7 +765,8 @@ copy_desc_to_mbuf(struct virtio_net *dev, struct vhost_virtqueue *vq,
while (desc_avail != 0 || (desc->flags & VRING_DESC_F_NEXT) != 0) {
/* This desc reaches to its end, get the next one */
if (desc_avail == 0) {
- if (unlikely(desc->next >= vq->size))
+ if (unlikely(desc->next >= vq->size ||
+ ++nr_desc >= vq->size))
return -1;
desc = &vq->desc[desc->next];
--
2.39.5