[Qemu-devel] [PATCH 2/4] qapi: output visitor crashes qemu if it encounters a NULL value

[Marcel Apfelbaum <marcel.a@redhat.com>]

A NULL value is not added to visitor's stack, but there
is no check for that when the visitor tries to return
that value, leading to Qemu crash.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Marcel Apfelbaum <marcel.a@redhat.com>
---
 qapi/qmp-output-visitor.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
index 74a5684..0562f49 100644
--- a/qapi/qmp-output-visitor.c
+++ b/qapi/qmp-output-visitor.c
@@ -66,6 +66,11 @@ static QObject *qmp_output_pop(QmpOutputVisitor *qov)
 static QObject *qmp_output_first(QmpOutputVisitor *qov)
 {
     QStackEntry *e = QTAILQ_LAST(&qov->stack, QStack);
+
+    if (!e) {
+        return NULL;
+    }
+
     return e->value;
 }
 
-- 
1.8.3.1