[dpdk-dev] [PATCH 3/4] vhost: fix potential use-after-free for memory region

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

Reclaim outstanding zmbufs first before freeing memory regions,
otherwise there could be use-after-free.

Fixes: b0a985d1f340 ("vhost: add dequeue zero copy")
Cc: stable@dpdk.org

Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
---
 lib/librte_vhost/vhost.h      |  6 +++++
 lib/librte_vhost/vhost_user.c | 46 +++++++++++++++++++++++++----------
 lib/librte_vhost/virtio_net.c |  6 -----
 3 files changed, 39 insertions(+), 19 deletions(-)

diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
index 044651b19..f008ec43b 100644
--- a/lib/librte_vhost/vhost.h
+++ b/lib/librte_vhost/vhost.h
@@ -769,4 +769,10 @@ mbuf_is_consumed(struct rte_mbuf *m)
 	return true;
 }
 
+static __rte_always_inline void
+put_zmbuf(struct zcopy_mbuf *zmbuf)
+{
+	zmbuf->in_use = 0;
+}
+
 #endif /* _VHOST_NET_CDEV_H_ */
diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index 6d8253514..36c0c676d 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -93,15 +93,47 @@ get_blk_size(int fd)
 	return ret == -1 ? (uint64_t)-1 : (uint64_t)stat.st_blksize;
 }
 
+/*
+ * Reclaim all the outstanding zmbufs for a virtqueue.
+ */
+static void
+drain_zmbuf_list(struct vhost_virtqueue *vq)
+{
+	struct zcopy_mbuf *zmbuf, *next;
+
+	for (zmbuf = TAILQ_FIRST(&vq->zmbuf_list);
+	     zmbuf != NULL; zmbuf = next) {
+		next = TAILQ_NEXT(zmbuf, next);
+
+		while (!mbuf_is_consumed(zmbuf->mbuf))
+			usleep(1000);
+
+		TAILQ_REMOVE(&vq->zmbuf_list, zmbuf, next);
+		restore_mbuf(zmbuf->mbuf);
+		rte_pktmbuf_free(zmbuf->mbuf);
+		put_zmbuf(zmbuf);
+		vq->nr_zmbuf -= 1;
+	}
+}
+
 static void
 free_mem_region(struct virtio_net *dev)
 {
 	uint32_t i;
 	struct rte_vhost_mem_region *reg;
+	struct vhost_virtqueue *vq;
 
 	if (!dev || !dev->mem)
 		return;
 
+	if (dev->dequeue_zero_copy) {
+		for (i = 0; i < dev->nr_vring; i++) {
+			vq = dev->virtqueue[i];
+			if (vq)
+				drain_zmbuf_list(vq);
+		}
+	}
+
 	for (i = 0; i < dev->mem->nregions; i++) {
 		reg = &dev->mem->regions[i];
 		if (reg->host_user_addr) {
@@ -1212,19 +1244,7 @@ vhost_user_set_vring_kick(struct virtio_net **pdev, struct VhostUserMsg *msg,
 static void
 free_zmbufs(struct vhost_virtqueue *vq)
 {
-	struct zcopy_mbuf *zmbuf, *next;
-
-	for (zmbuf = TAILQ_FIRST(&vq->zmbuf_list);
-	     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);
-	}
+	drain_zmbuf_list(vq);
 
 	rte_free(vq->zmbufs);
 }
diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
index 40a292364..a6a33a101 100644
--- a/lib/librte_vhost/virtio_net.c
+++ b/lib/librte_vhost/virtio_net.c
@@ -1063,12 +1063,6 @@ vhost_dequeue_offload(struct virtio_net_hdr *hdr, struct rte_mbuf *m)
 	}
 }
 
-static __rte_always_inline void
-put_zmbuf(struct zcopy_mbuf *zmbuf)
-{
-	zmbuf->in_use = 0;
-}
-
 static __rte_always_inline int
 copy_desc_to_mbuf(struct virtio_net *dev, struct vhost_virtqueue *vq,
 		  struct buf_vector *buf_vec, uint16_t nr_vec,
-- 
2.17.1