[Qemu-devel] [PULL 4/8] qapi: Avoid output visitor crashing if it encounters a NULL value

[Andreas Färber]

From: Marcel Apfelbaum <address@hidden>

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 <address@hidden>
Acked-by: Luiz Capitulino <address@hidden>
Signed-off-by: Marcel Apfelbaum <address@hidden>
Acked-by: Michael S. Tsirkin <address@hidden>
Acked-by: Michael Roth <address@hidden>
Signed-off-by: Andreas Färber <address@hidden>
---
 qapi/qmp-output-visitor.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
index 74a5684..96b3384 100644
--- a/qapi/qmp-output-visitor.c
+++ b/qapi/qmp-output-visitor.c
@@ -66,6 +66,12 @@ static QObject *qmp_output_pop(QmpOutputVisitor *qov)
 static QObject *qmp_output_first(QmpOutputVisitor *qov)
 {
     QStackEntry *e = QTAILQ_LAST(&qov->stack, QStack);
+
+    /* FIXME - find a better way to deal with NULL values */
+    if (!e) {
+        return NULL;
+    }
+
     return e->value;
 }
 
-- 
1.8.4.5