PHP - variables not comparing to one another - php

Question

I am doing a password reset page for my website and when a user puts a new password on the <form method="post" action="passVerif.php"> it goes to the PHP with this code:
Until now I cannot make the php compare the two new entered passwords to verify if they are equal or not, it simply jumps over that part.
P.S. don't mind the $senha = md5($password) it is like this for easy troubleshoot on localhost (MAMP).
<?php
session_start();
include("connectivity.php");
$user_id = $_SESSION['ResetUtilizadorID'];
$password1 = $_POST['password1'];
$password2 = $_POST['password2'];
$sql = mysqli_query($conn, "SELECT FROM usuarios WHERE id =".$user_id."");
$password = $password1;
$senha = md5($password);
$adminID = $_SESSION['usuarioNiveisAcessoId'];
if (strcmp($user_id,$adminID) == 0) {
$_SESSION['avisoReset'] = "not possible to change admin password.";
header('Location: ../login/reset_password.php');
} else {
while ($row = mysqli_fetch_array($query)) {
if ($senha == $row['senha']){
$_SESSION['avisoReset'] = "password taken";
header('Location: ../login/reset_password.php');
}
}
if ($password1 == $password2){
mysqli_query($conn, "UPDATE usuarios SET senha = '".$senha."' WHERE id='".$user_id."'");
$sql = 'SELECT * FROM usuarios';
$query = mysqli_query($conn, $sql);
if (!$query) {
die ('SQL Error: ' . mysqli_error($conn));
}
$_SESSION['avisoReset'] = "new passoword set";
//header('Location: ../login/reset_password.php');
} else {
$_SESSION['avisoReset'] = "Passwords not equal!";
header('Location: ../login/reset_password.php');
}
}
?>

Answer 1

Why are you using strpos? strpos finds the position of the first occurrence of a substring in a string. So the password could be a subset of another string (the stored password) and still evaluate to true for your use case.
if (strpos($user_id,$adminID) == true)
You should instead use strcmp (Binary safe string comparison):
if (strcmp($user_id,$adminID) == 0)

Answer 2

I solved the problem by adding a username and then comparing the user input data to the DB. So the problem of multiple users by any chance use the same password it is all good.