block: Don't attach inactive child to active node

An active node makes unrestricted use of its children and would possibly
run into assertion failures when it operates on an inactive child node.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20250204211407.381505-6-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/block.c b/block.c
index 9458c5e..66a99e8 100644
--- a/block.c
+++ b/block.c
@@ -3183,6 +3183,11 @@ bdrv_attach_child_noperm(BlockDriverState *parent_bs,
                    child_bs->node_name, child_name, parent_bs->node_name);
         return NULL;
     }
+    if (bdrv_is_inactive(child_bs) && !bdrv_is_inactive(parent_bs)) {
+        error_setg(errp, "Inactive '%s' can't be a %s child of active '%s'",
+                   child_bs->node_name, child_name, parent_bs->node_name);
+        return NULL;
+    }
 
     bdrv_get_cumulative_perm(parent_bs, &perm, &shared_perm);
     bdrv_child_perm(parent_bs, child_bs, NULL, child_role, NULL,