We miss call to unmap in cases when vhost_memory_map() returns
lenght less than requested (still we consider such cases as an
error). Let's fix it in vhost_memory_map().

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Raphael Norwitz <raphael.s.norwitz@gmail.com>
---
 hw/virtio/vhost.c | 27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index b89670e385..fed7c0f4ec 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -454,11 +454,20 @@ static inline void vhost_dev_log_resize(struct vhost_dev *dev, uint64_t size)
 }
 
 static void *vhost_memory_map(struct vhost_dev *dev, hwaddr addr,
-                              hwaddr *plen, bool is_write)
+                              hwaddr len, bool is_write)
 {
     if (!vhost_dev_has_iommu(dev)) {
-        return address_space_map(dev->vdev->dma_as, addr, plen, is_write,
-                                 MEMTXATTRS_UNSPECIFIED);
+        hwaddr mapped_len = len;
+        void *res = address_space_map(dev->vdev->dma_as, addr, &mapped_len,
+                                      is_write, MEMTXATTRS_UNSPECIFIED);
+        if (!res) {
+            return NULL;
+        }
+        if (len != mapped_len) {
+            address_space_unmap(dev->vdev->dma_as, res, mapped_len, 0, 0);
+            return NULL;
+        }
+        return res;
     } else {
         return (void *)(uintptr_t)addr;
     }
@@ -1314,22 +1323,22 @@ int vhost_virtqueue_start(struct vhost_dev *dev,
     }
 
     l = vq->desc_size;
-    vq->desc = vhost_memory_map(dev, vq->desc_phys, &l, false);
-    if (!vq->desc || l != vq->desc_size) {
+    vq->desc = vhost_memory_map(dev, vq->desc_phys, l, false);
+    if (!vq->desc) {
         r = -ENOMEM;
         goto fail_alloc_desc;
     }
 
     l = vq->avail_size;
-    vq->avail = vhost_memory_map(dev, vq->avail_phys, &l, false);
-    if (!vq->avail || l != vq->avail_size) {
+    vq->avail = vhost_memory_map(dev, vq->avail_phys, l, false);
+    if (!vq->avail) {
         r = -ENOMEM;
         goto fail_alloc_avail;
     }
 
     l = vq->used_size;
-    vq->used = vhost_memory_map(dev, vq->used_phys, &l, true);
-    if (!vq->used || l != vq->used_size) {
+    vq->used = vhost_memory_map(dev, vq->used_phys, l, true);
+    if (!vq->used) {
         r = -ENOMEM;
         goto fail_alloc_used;
     }
-- 
2.52.0