[Stable-8.1.2 53/57] vdpa net: zero vhost_vdpa iova_tree pointer at cleanup

[Michael Tokarev]

From: 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>
Message-Id: <20230913123408.2819185-1-eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Si-Wei Liu <si-wei.liu@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
(cherry picked from commit 0a7a164bc37b4ecbf74466e1e5243d72a768ad06)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index 9795306742..977faeb44b 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;
     }
 }
 
-- 
2.39.2