[PATCH v2 2/7] vhost: fix missing check on virtqueue access

[Maxime Coquelin]

Acquiring the access lock is not enough to ensure
virtqueue's metadata such as vring pointers are valid.

The access status must also be checked.

Fixes: 4e0de8dac853 ("vhost: protect vring access done by application")
Cc: sta...@dpdk.org

Signed-off-by: Maxime Coquelin <maxime.coque...@redhat.com>
---
 lib/vhost/vhost.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c
index 0d2bc1a48b..446bca1574 100644
--- a/lib/vhost/vhost.c
+++ b/lib/vhost/vhost.c
@@ -1418,7 +1418,10 @@ rte_vhost_avail_entries(int vid, uint16_t queue_id)
 
        rte_rwlock_write_lock(&vq->access_lock);
 
-       if (unlikely(!vq->enabled || vq->avail == NULL))
+       if (unlikely(!vq->access_ok))
+               goto out;
+
+       if (unlikely(!vq->enabled))
                goto out;
 
        ret = *(volatile uint16_t *)&vq->avail->idx - vq->last_used_idx;
@@ -1510,9 +1513,15 @@ rte_vhost_enable_guest_notification(int vid, uint16_t 
queue_id, int enable)
 
        rte_rwlock_write_lock(&vq->access_lock);
 
+       if (unlikely(!vq->access_ok)) {
+               ret = -1;
+               goto out_unlock;
+       }
+
        vq->notif_enable = enable;
        ret = vhost_enable_guest_notification(dev, vq, enable);
 
+out_unlock:
        rte_rwlock_write_unlock(&vq->access_lock);
 
        return ret;
@@ -1605,7 +1614,10 @@ rte_vhost_rx_queue_count(int vid, uint16_t qid)
 
        rte_rwlock_write_lock(&vq->access_lock);
 
-       if (unlikely(!vq->enabled || vq->avail == NULL))
+       if (unlikely(!vq->access_ok))
+               goto out;
+
+       if (unlikely(!vq->enabled))
                goto out;
 
        ret = *((volatile uint16_t *)&vq->avail->idx) - vq->last_avail_idx;
-- 
2.41.0