[dpdk-stable] [PATCH 17.11 2/3] vhost: fix potential use-after-free for zero copy mbuf

[Tiwei Bie <tiwei.bie@intel.com>]

[ backported from upstream commit d767436ee5d26d1d417ae17d1a2a47879bf632a6 ]

Don't free the zero copy mbufs before they have been consumed,
otherwise there could be use-after-free.

Fixes: b0a985d1f340 ("vhost: add dequeue zero copy")

Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
 lib/librte_vhost/vhost.h      | 12 ++++++++++++
 lib/librte_vhost/vhost_user.c |  3 +++
 lib/librte_vhost/virtio_net.c | 12 ------------
 3 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
index c9e86a2c9..ccd6c015c 100644
--- a/lib/librte_vhost/vhost.h
+++ b/lib/librte_vhost/vhost.h
@@ -529,4 +529,16 @@ restore_mbuf(struct rte_mbuf *m)
 	}
 }
 
+static __rte_always_inline bool
+mbuf_is_consumed(struct rte_mbuf *m)
+{
+	while (m) {
+		if (rte_mbuf_refcnt_read(m) > 1)
+			return false;
+		m = m->next;
+	}
+
+	return true;
+}
+
 #endif /* _VHOST_NET_CDEV_H_ */
diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index 7c0d8c6e4..63b200127 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -888,6 +888,9 @@ free_zmbufs(struct vhost_virtqueue *vq)
 	     zmbuf != NULL; zmbuf = next) {
 		next = TAILQ_NEXT(zmbuf, next);
 
+		while (!mbuf_is_consumed(zmbuf->mbuf))
+			usleep(1000);
+
 		restore_mbuf(zmbuf->mbuf);
 		rte_pktmbuf_free(zmbuf->mbuf);
 		TAILQ_REMOVE(&vq->zmbuf_list, zmbuf, next);
diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
index e3d50c96b..71d3d9c5b 100644
--- a/lib/librte_vhost/virtio_net.c
+++ b/lib/librte_vhost/virtio_net.c
@@ -1454,18 +1454,6 @@ get_zmbuf(struct vhost_virtqueue *vq)
 	return NULL;
 }
 
-static __rte_always_inline bool
-mbuf_is_consumed(struct rte_mbuf *m)
-{
-	while (m) {
-		if (rte_mbuf_refcnt_read(m) > 1)
-			return false;
-		m = m->next;
-	}
-
-	return true;
-}
-
 uint16_t
 rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
 	struct rte_mempool *mbuf_pool, struct rte_mbuf **pkts, uint16_t count)
-- 
2.17.1