[PATCH 2/2] gdbus: Fix crash in g_dbus_create_error_valist

[Szymon Janc <szymon.janc@tieto.com>]

Passing NULL format parameter to vsnprintf results in invalid argument
error on glibc. But with some other libc libraries (musl and uClibc)
this results in dereferencing NULL pointer and crash due to
segmentation fault.
---
 gdbus/object.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/gdbus/object.c b/gdbus/object.c
index c3c137b..74e975b 100644
--- a/gdbus/object.c
+++ b/gdbus/object.c
@@ -1412,7 +1412,10 @@ DBusMessage *g_dbus_create_error_valist(DBusMessage *message, const char *name,
 {
 	char str[1024];
 
-	vsnprintf(str, sizeof(str), format, args);
+	if (format)
+		vsnprintf(str, sizeof(str), format, args);
+	else
+		str[0] = '\0';
 
 	return dbus_message_new_error(message, name, str);
 }
-- 
1.9.3