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[Qemu-devel] [PATCH] qmp_output_visitor_cleanup(): fix double free
From: |
Laszlo Ersek |
Subject: |
[Qemu-devel] [PATCH] qmp_output_visitor_cleanup(): fix double free |
Date: |
Fri, 16 Mar 2012 20:16:12 +0100 |
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: Laszlo Ersek <address@hidden>
---
qapi/qmp-output-visitor.c | 8 +++++---
1 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
index e0697b0..2bce9d5 100644
--- a/qapi/qmp-output-visitor.c
+++ b/qapi/qmp-output-visitor.c
@@ -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);
}
--
1.7.1