[Qemu-devel] [PULL 2/5] hostmem: fix crash when querying empty host-nodes property via QMP

[Eduardo Habkost]

From: Igor Mammedov <address@hidden>

QEMU will crashes with
 qapi/qobject-output-visitor.c:210: qobject_output_complete: Assertion 
`qov->root && ((&qov->stack)->slh_first == ((void *)0))' failed
when trying to get value of not set hostmem's "host-nodes"
property, HostMemoryBackend::host_nodes bitmap doesn't have
any bits set in it, which leads to find_first_bit() returning
MAX_NODES and consequently to an early return from
host_memory_backend_get_host_nodes() without calling visitor.

Fix it by calling visitor even if "host-nodes" property wasn't
set before exiting from property getter to return valid empty
list.

Signed-off-by: Igor Mammedov <address@hidden>
Message-Id: <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
Reviewed-by: Stefano Garzarella <address@hidden>
Signed-off-by: Eduardo Habkost <address@hidden>
---
 backends/hostmem.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/backends/hostmem.c b/backends/hostmem.c
index 87b19d2111..04baf479a1 100644
--- a/backends/hostmem.c
+++ b/backends/hostmem.c
@@ -88,7 +88,7 @@ host_memory_backend_get_host_nodes(Object *obj, Visitor *v, 
const char *name,
 
     value = find_first_bit(backend->host_nodes, MAX_NODES);
     if (value == MAX_NODES) {
-        return;
+        goto ret;
     }
 
     *node = g_malloc0(sizeof(**node));
@@ -106,6 +106,7 @@ host_memory_backend_get_host_nodes(Object *obj, Visitor *v, 
const char *name,
         node = &(*node)->next;
     } while (true);
 
+ret:
     visit_type_uint16List(v, name, &host_nodes, errp);
 }
 
-- 
2.18.0.rc1.1.g3f1ff2140