From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:50101) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SCVOQ-0000sC-NC for qemu-devel@nongnu.org; Tue, 27 Mar 2012 08:21:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SCVOK-0000IC-AE for qemu-devel@nongnu.org; Tue, 27 Mar 2012 08:20:54 -0400 Received: from mx1.redhat.com ([209.132.183.28]:7898) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SCVOK-0000Hn-27 for qemu-devel@nongnu.org; Tue, 27 Mar 2012 08:20:48 -0400 From: Luiz Capitulino Date: Tue, 27 Mar 2012 09:20:39 -0300 Message-Id: <1332850851-4059-2-git-send-email-lcapitulino@redhat.com> In-Reply-To: <1332850851-4059-1-git-send-email-lcapitulino@redhat.com> References: <1332850851-4059-1-git-send-email-lcapitulino@redhat.com> Subject: [Qemu-devel] [PATCH 01/13] qapi: fix double free in qmp_output_visitor_cleanup() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: aliguori@us.ibm.com Cc: Laszlo Ersek , qemu-devel@nongnu.org From: Laszlo Ersek 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 Signed-off-by: Luiz Capitulino --- qapi/qmp-output-visitor.c | 8 +++++--- 1 file 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); } -- 1.7.9.2.384.g4a92a