From 62caf1b8cc3625fa208bddb35d3ae7bda6123440 Mon Sep 17 00:00:00 2001 Message-Id: <62caf1b8cc3625fa208bddb35d3ae7bda6123440.1334225653.git.minovotn@redhat.com> From: Luiz Capitulino Date: Mon, 9 Apr 2012 19:31:24 +0200 Subject: [PATCH] qapi: fix double free in qmp_output_visitor_cleanup() RH-Author: Luiz Capitulino Message-id: <20120409163124.07e70ca1@doriath.home> Patchwork-id: 39136 O-Subject: [RHEL6.3 qemu-kvm PATCH] qapi: fix double free in qmp_output_visitor_cleanup() Bugzilla: 810983 RH-Acked-by: Laszlo Ersek RH-Acked-by: Paolo Bonzini RH-Acked-by: Jeffrey Cody Bugzilla: 810983 Upstream-status: Merged 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 (cherry picked from commit f24582d6ad8a080e008974c000bf0ae635d036ac) Conflicts: qapi/qmp-output-visitor.c Signed-off-by: Luiz Capitulino --- NOTE: I'm not backporting the test-case that was merged along with this patch (upstream commit 9e9eace89e) because the qapi test suite we have in 6.3 is outdated. Actually, it doesn't even build :( qapi/qmp-output-visitor.c | 8 +++++--- 1 files changed, 5 insertions(+), 3 deletions(-) Signed-off-by: Michal Novotny --- 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 4441511..9873bc9 100644 --- a/qapi/qmp-output-visitor.c +++ b/qapi/qmp-output-visitor.c @@ -217,14 +217,16 @@ 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); - } qemu_free(e); } + qobject_decref(root); qemu_free(v); } -- 1.7.7.6