bugfix: hostmem: Free host_nodes list right after visited

In host_memory_backend_get_host_nodes, we build host_nodes
list and output it to v (a StringOutputVisitor) but forget
to free the list. This fixes the memory leak.

The memory leak stack:

 Direct leak of 32 byte(s) in 2 object(s) allocated from:
    #0 0xfffda30b3393 in __interceptor_calloc (/usr/lib64/libasan.so.4+0xd3393)
    #1 0xfffda1d28b9b in g_malloc0 (/usr/lib64/libglib-2.0.so.0+0x58b9b)
    #2 0xaaab05ca6e43 in host_memory_backend_get_host_nodes backends/hostmem.c:94
    #3 0xaaab061ddf83 in object_property_get_uint16List qom/object.c:1478
    #4 0xaaab05866513 in query_memdev hw/core/machine-qmp-cmds.c:312
    #5 0xaaab061d980b in do_object_child_foreach qom/object.c:1001
    #6 0xaaab0586779b in qmp_query_memdev hw/core/machine-qmp-cmds.c:328
    #7 0xaaab0615ed3f in qmp_marshal_query_memdev qapi/qapi-commands-machine.c:327
    #8 0xaaab0632d647 in do_qmp_dispatch qapi/qmp-dispatch.c:147
    #9 0xaaab0632d647 in qmp_dispatch qapi/qmp-dispatch.c:190
    #10 0xaaab0610f74b in monitor_qmp_dispatch monitor/qmp.c:120
    #11 0xaaab0611074b in monitor_qmp_bh_dispatcher monitor/qmp.c:209
    #12 0xaaab063caefb in aio_bh_poll util/async.c:117
    #13 0xaaab063d30fb in aio_dispatch util/aio-posix.c:459
    #14 0xaaab063cac8f in aio_ctx_dispatch util/async.c:268
    qemu#15 0xfffda1d22a6b in g_main_context_dispatch (/usr/lib64/libglib-2.0.so.0+0x52a6b)
    qemu#16 0xaaab063d0e97 in glib_pollfds_poll util/main-loop.c:218
    qemu#17 0xaaab063d0e97 in os_host_main_loop_wait util/main-loop.c:241
    qemu#18 0xaaab063d0e97 in main_loop_wait util/main-loop.c:517
    qemu#19 0xaaab05c8bfa7 in main_loop /root/rpmbuild/BUILD/qemu-4.1.0/vl.c:1791
    qemu#20 0xaaab05713bc3 in main /root/rpmbuild/BUILD/qemu-4.1.0/vl.c:4473
    qemu#21 0xfffda0a83ebf in __libc_start_main (/usr/lib64/libc.so.6+0x23ebf)
    qemu#22 0xaaab0571ed5f  (aarch64-softmmu/qemu-system-aarch64+0x88ed5f)
 SUMMARY: AddressSanitizer: 32 byte(s) leaked in 2 allocation(s).

Fixes: 4cf1b76 (hostmem: add properties for NUMA memory policy)
Reported-by: Euler Robot <euler.robot@huawei.com>
Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
Tested-by: Chen Qun <kuhn.chenqun@huawei.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20201210075226.20196-1-zhukeqian1@huawei.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

backends/hostmem.c

@@ -105,6 +105,7 @@ host_memory_backend_get_host_nodes(Object *obj, Visitor *v, const char *name,
 
 ret:
     visit_type_uint16List(v, name, &host_nodes, errp);
+    qapi_free_uint16List(host_nodes);
 }
 
 static void