diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c
index a260cde743e2..2db68dfe497d 100644
--- a/drivers/tty/serial/kgdboc.c
+++ b/drivers/tty/serial/kgdboc.c
@@ -133,6 +133,11 @@ static void kgdboc_unregister_kbd(void)
 
 static int kgdboc_option_setup(char *opt)
 {
+	if (!opt) {
+		pr_err("kgdboc: config string not provided\n");
+		return -EINVAL;
+	}
+
 	if (strlen(opt) >= MAX_CONFIG_LEN) {
 		printk(KERN_ERR "kgdboc: config string too long\n");
 		return -ENOSPC;