[PATCH] vdpa net: zero vhost_vdpa iova_tree pointer at cleanup

["Eugenio Pérez" <eperezma@redhat.com>]

Not zeroing it causes a SIGSEGV if the live migration is cancelled, at
net device restart.

This is caused because CVQ tries to reuse the iova_tree that is present
in the first vhost_vdpa device at the end of vhost_vdpa_net_cvq_start.
As a consequence, it tries to access an iova_tree that has been already
free.

Fixes: 00ef422e9fbf ("vdpa net: move iova tree creation from init to start")
Reported-by: Yanhui Ma <yama@redhat.com>
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 net/vhost-vdpa.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index 34202ca009..1714ff4b11 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -385,6 +385,8 @@ static void vhost_vdpa_net_client_stop(NetClientState *nc)
     dev = s->vhost_vdpa.dev;
     if (dev->vq_index + dev->nvqs == dev->vq_index_end) {
         g_clear_pointer(&s->vhost_vdpa.iova_tree, vhost_iova_tree_delete);
+    } else {
+        s->vhost_vdpa.iova_tree = NULL;
     }
 }
 
-- 
2.39.3