do not accept "kernel messages" from userspace

diff --git a/message.c b/message.c
index 16db583768eef879290f4becc1657a17f7c66adb..94cfc2cd06465072b0b9f125d5ec4bd9794459af 100644 (file)
--- a/message.c
+++ b/message.c
@@ -269,6 +269,12 @@ int kdbus_kmsg_new_from_user(struct kdbus_conn *conn,
                goto exit_free;
        }
 
+       /* do not accept kernel-generated messages */
+       if (m->msg.payload_type == 0) {
+               ret = -EINVAL;
+               goto exit_free;
+       }
+
        /* requests for replies need a timeout */
        if (m->msg.flags & KDBUS_MSG_FLAGS_EXPECT_REPLY &&
            m->msg.timeout_ns == 0) {