Output of default values in device help is broken:
$ ./qemu-system-x86_64 -S -display none -monitor stdio
QEMU 5.2.50 monitor - type 'help' for more information
(qemu) device_add pvpanic,help
pvpanic options:
events=<uint8> - (default: (null))
ioport=<uint16> - (default: (null))
pvpanic[0]=<child<qemu:memory-region>>
The "(null)" is glibc printing a null pointer. Other systems crash
instead. Having a help request crash a running VM can really spoil
your day.
Root cause is a botched replacement of qstring_free() by
g_string_free(): to get the string back, we need to pass true to the
former, but false to the latter. Fix the argument.
Fixes: eab3a4678b07267c39e7290a6e9e7690b1d2a521
Reported-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
qom/object_interfaces.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/qom/object_interfaces.c b/qom/object_interfaces.c
index c3324b0f86..bd8a947a63 100644
--- a/qom/object_interfaces.c
+++ b/qom/object_interfaces.c
@@ -159,7 +159,7 @@ char *object_property_help(const char *name, const char
*type,
}
if (defval) {
g_autofree char *def_json = g_string_free(qobject_to_json(defval),
- true);
+ false);
g_string_append_printf(str, " (default: %s)", def_json);
}