AES GCM mode and the message is the same as the password In a case of using a password and get AES key using KDF to encrypt the same password (The password and the message is the same), How secure is that algorithm ?
From Wikipedia Key Derivation Function (KDF):


  In cryptography, a key derivation function (KDF) derives one or more secret keys from a secret value such as a master key, a password, or a passphrase using a pseudorandom function


You have a password $p$, and you are using a KDF $k=KDF(p)$ to derive the key $k$ and then you encrypt the $p$ as $c=E_k(p)$, where $E$ is AES. 

There is a problem here. How are you going to remember the $k$, if you keep the $p$, then what is the aim of encrypting it?

If you look at password manager you will see that;


  Password managers typically require a user to generate and remember one "master" password to unlock and access any information stored in their databases. 


One of the benefits of KDF is we input to KDF a human rememberable password to generate cryptographic keys.

You have to use some way to store the $k$ if you delete/forget $p$ and input whenever necessary. Also, $k$ is generated what is the aim of encrypting the $p$? Just delete it?




and remember AES-GCM is authenticated encryption mode.