Commit b5a420cb113beeb84b4aa02fe5d22b49722d598a
2018-07-13T17:53:24
dbus: Deal with undefined behavior with va_args. Parse out a copy of the varargs ourselves to get to the reply portion, since the original passed to D-Bus might modify or not modify the caller's copy, depending on system ABI.
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diff --git a/src/core/linux/SDL_dbus.c b/src/core/linux/SDL_dbus.c
index ff4f0fe..e0d9972 100644
--- a/src/core/linux/SDL_dbus.c
+++ b/src/core/linux/SDL_dbus.c
@@ -173,17 +173,29 @@ SDL_DBus_CallMethodInternal(DBusConnection *conn, const char *node, const char *
if (conn) {
DBusMessage *msg = dbus.message_new_method_call(node, path, interface, method);
if (msg) {
- int firstarg = va_arg(ap, int);
+ int firstarg;
+ va_list ap_reply;
+ va_copy(ap_reply, ap); /* copy the arg list so we don't compete with D-Bus for it */
+ firstarg = va_arg(ap, int);
if ((firstarg == DBUS_TYPE_INVALID) || dbus.message_append_args_valist(msg, firstarg, ap)) {
DBusMessage *reply = dbus.connection_send_with_reply_and_block(conn, msg, 300, NULL);
if (reply) {
- firstarg = va_arg(ap, int);
- if ((firstarg == DBUS_TYPE_INVALID) || dbus.message_get_args_valist(reply, NULL, firstarg, ap)) {
+ /* skip any input args, get to output args. */
+ while ((firstarg = va_arg(ap_reply, int)) != DBUS_TYPE_INVALID) {
+ /* we assume D-Bus already validated all this. */
+ { void *dumpptr = va_arg(ap_reply, void*); (void) dumpptr; }
+ if (firstarg == DBUS_TYPE_ARRAY) {
+ { const int dumpint = va_arg(ap_reply, int); (void) dumpint; }
+ }
+ }
+ firstarg = va_arg(ap_reply, int);
+ if ((firstarg == DBUS_TYPE_INVALID) || dbus.message_get_args_valist(reply, NULL, firstarg, ap_reply)) {
retval = SDL_TRUE;
}
dbus.message_unref(reply);
}
}
+ va_end(ap_reply);
dbus.message_unref(msg);
}
}