Fixed security vulnerability if writing unterminated max length string.

20160425/chardev-1write.c

@@ -183,7 +183,7 @@ device_write(struct file *filp, const char *buff, size_t len, loff_t * off)
 	/* Since nobody wants to read I have to correct the already told you
 	   counter! */
 	told_you_counter--;
-	if(len > USERBUF_LEN) {
+	if(len >= USERBUF_LEN) {
 		printk(	KERN_WARNING 
 			"%s: Sorry, your input is too long. Max %d allowed!\n",
 			DEVICE_NAME,