Commit f24582d6 authored by Laszlo Ersek's avatar Laszlo Ersek Committed by Luiz Capitulino
Browse files

qapi: fix double free in qmp_output_visitor_cleanup() 

Stack entries in QmpOutputVisitor are navigation links (weak references),
except the bottom (ie. least recently added) entry, which owns the root
QObject [1]. Make qmp_output_visitor_cleanup() drop the stack entries,
then release the QObject tree by the root.

Attempting to serialize an invalid enum inside a dictionary is an example
for triggering the double free.

[1] http://lists.nongnu.org/archive/html/qemu-devel/2012-03/msg03276.html



Signed-off-by: default avatarLaszlo Ersek <lersek@redhat.com>
Signed-off-by: default avatarLuiz Capitulino <lcapitulino@redhat.com>
parent 8a22565b

qapi/qmp-output-visitor.c

+5 −3
Original line number Diff line number Diff line
@@ -199,14 +199,16 @@ void qmp_output_visitor_cleanup(QmpOutputVisitor *v) 
{

    QStackEntry *e, *tmp;



    /* The bottom QStackEntry, if any, owns the root QObject. See the

     * qmp_output_push_obj() invocations in qmp_output_add_obj(). */

    QObject *root = QTAILQ_EMPTY(&v->stack) ? NULL : qmp_output_first(v);



    QTAILQ_FOREACH_SAFE(e, &v->stack, node, tmp) {

        QTAILQ_REMOVE(&v->stack, e, node);

        if (e->value) {

            qobject_decref(e->value);

        }

        g_free(e);

    }



    qobject_decref(root);

    g_free(v);

}