From 25461d8eac80c0f1242150f7316ec58ac14c5d39 Mon Sep 17 00:00:00 2001
From: Andrey Andreev <narf@devilix.net>
Date: Thu, 19 Jan 2017 15:42:43 +0200
Subject: hash_pbkdf2() byte-safety

---
 system/core/compat/hash.php         | 17 +++++++++++++----
 user_guide_src/source/changelog.rst |  2 +-
 2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/system/core/compat/hash.php b/system/core/compat/hash.php
index ba0198e10..7eb292188 100644
--- a/system/core/compat/hash.php
+++ b/system/core/compat/hash.php
@@ -173,7 +173,9 @@ if ( ! function_exists('hash_pbkdf2'))
 			return FALSE;
 		}
 
-		$hash_length = strlen(hash($algo, NULL, TRUE));
+		$hash_length = defined('MB_OVERLOAD_STRING')
+			? mb_strlen(hash($algo, NULL, TRUE))
+			: strlen(hash($algo, NULL, TRUE));
 		empty($length) && $length = $hash_length;
 
 		// Pre-hash password inputs longer than the algorithm's block size
@@ -221,14 +223,14 @@ if ( ! function_exists('hash_pbkdf2'))
 			'whirlpool' => 64
 		);
 
-		if (isset($block_sizes[$algo]) && strlen($password) > $block_sizes[$algo])
+		if (isset($block_sizes[$algo], $password[$block_sizes[$algo]]))
 		{
 			$password = hash($algo, $password, TRUE);
 		}
 
 		$hash = '';
 		// Note: Blocks are NOT 0-indexed
-		for ($bc = ceil($length / $hash_length), $bi = 1; $bi <= $bc; $bi++)
+		for ($bc = (int) ceil($length / $hash_length), $bi = 1; $bi <= $bc; $bi++)
 		{
 			$key = $derived_key = hash_hmac($algo, $salt.pack('N', $bi), $password, TRUE);
 			for ($i = 1; $i < $iterations; $i++)
@@ -240,6 +242,13 @@ if ( ! function_exists('hash_pbkdf2'))
 		}
 
 		// This is not RFC-compatible, but we're aiming for natural PHP compatibility
-		return substr($raw_output ? $hash : bin2hex($hash), 0, $length);
+		if ( ! $raw_output)
+		{
+			$hash = bin2hex($hash);
+		}
+
+		return defined('MB_OVERLOAD_STRING')
+			? mb_substr($hash, 0, $length)
+			: substr($hash, 0, $length);
 	}
 }
diff --git a/user_guide_src/source/changelog.rst b/user_guide_src/source/changelog.rst
index 7d1302b3a..ce82f071c 100644
--- a/user_guide_src/source/changelog.rst
+++ b/user_guide_src/source/changelog.rst
@@ -12,7 +12,7 @@ Release Date: Not Released
    -  Updated :doc:`Encrypt Library <libraries/encrypt>` (DEPRECATED) to call ``mcrypt_create_iv()`` with ``MCRYPT_DEV_URANDOM``.
    -  Fixed byte-safety issues in :doc:`Encrypt Library <libraries/encrypt>` (DEPRECATED) when ``mbstring.func_overload`` is enabled.
    -  Fixed byte-safety issues in :doc:`Encryption Library <libraries/encryption>` when ``mbstring.func_overload`` is enabled.
-   -  Fixed byte-safety issues in :doc:`compatibility function <general/compatibility_functions>` ``password_hash()`` when ``mbstring.func_overload`` is enabled.
+   -  Fixed byte-safety issues in :doc:`compatibility functions <general/compatibility_functions>` ``password_hash()``, ``hash_pbkdf2()`` when ``mbstring.func_overload`` is enabled.
 
 -  General Changes
 
-- 
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