[dpdk-stable] [v17.11 PATCH v2 1/4] vhost: validate virtqueue size

[Maxime Coquelin <maxime.coquelin@redhat.com>]

From: Stefan Hajnoczi <stefanha@redhat.com>

[ backported from upstream commit eb7c574b21cc92792ea5a1f219ddf6dd3cf3b1e1 ]

Check the virtqueue size constraints so that invalid values don't cause
bugs later on in the code.  For example, sometimes the virtqueue size is
stored as unsigned int and sometimes as uint16_t, so bad things happen
if it is ever larger than 65535.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
 lib/librte_vhost/vhost_user.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index bb39999aa4..93e871c5bb 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -247,6 +247,17 @@ vhost_user_set_vring_num(struct virtio_net *dev,
 
 	vq->size = msg->payload.state.num;
 
+	/* VIRTIO 1.0, 2.4 Virtqueues says:
+	 *
+	 *   Queue Size value is always a power of 2. The maximum Queue Size
+	 *   value is 32768.
+	 */
+	if ((vq->size & (vq->size - 1)) || vq->size > 32768) {
+		RTE_LOG(ERR, VHOST_CONFIG,
+			"invalid virtqueue size %u\n", vq->size);
+		return -1;
+	}
+
 	if (dev->dequeue_zero_copy) {
 		vq->nr_zmbuf = 0;
 		vq->last_zmbuf_idx = 0;
-- 
2.21.0