[Qemu-devel] [PATCH v4 06/29] vhost: fix cleanup on not fully initialized device

[marcandre . lureau]

From: Marc-André Lureau <address@hidden>

If vhost_dev_init() failed, caller may still call vhost_dev_cleanup()
later. However, vhost_dev_cleanup() tries to remove the device from the
list even if it wasn't yet added, which may lead to crashes. Similarly
for the memory listener.

Signed-off-by: Marc-André Lureau <address@hidden>
---
 hw/virtio/vhost.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index b229efd..08fb336 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -1011,7 +1011,6 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
         r = -1;
         goto fail;
     }
-    QLIST_INSERT_HEAD(&vhost_devices, hdev, entry);
 
     r = hdev->vhost_ops->vhost_set_owner(hdev);
     if (r < 0) {
@@ -1070,6 +1069,7 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
     hdev->started = false;
     hdev->memory_changed = false;
     memory_listener_register(&hdev->memory_listener, &address_space_memory);
+    QLIST_INSERT_HEAD(&vhost_devices, hdev, entry);
     return 0;
 fail_vq:
     while (--i >= 0) {
@@ -1088,7 +1088,11 @@ void vhost_dev_cleanup(struct vhost_dev *hdev)
     for (i = 0; i < hdev->nvqs; ++i) {
         vhost_virtqueue_cleanup(hdev->vqs + i);
     }
-    memory_listener_unregister(&hdev->memory_listener);
+    if (hdev->mem) {
+        /* those are only safe after successful init */
+        memory_listener_unregister(&hdev->memory_listener);
+        QLIST_REMOVE(hdev, entry);
+    }
     if (hdev->migration_blocker) {
         migrate_del_blocker(hdev->migration_blocker);
         error_free(hdev->migration_blocker);
@@ -1097,7 +1101,6 @@ void vhost_dev_cleanup(struct vhost_dev *hdev)
     g_free(hdev->mem_sections);
     hdev->vhost_ops->vhost_backend_cleanup(hdev);
     assert(!hdev->log);
-    QLIST_REMOVE(hdev, entry);
 }
 
 /* Stop processing guest IO notifications in qemu.
-- 
2.9.0