Doc #77218 [Com]: password_hash returns null on failure instead of false as of PHP 7.4

From: Date: Sun, 17 Feb 2019 04:08:44 +0000
Subject: Doc #77218 [Com]: password_hash returns null on failure instead of false as of PHP 7.4
References: 1  Groups: php.doc.bugs 
Request: Send a blank email to doc-bugs+get-16414@lists.php.net to get a copy of this message 
Edit report at https://bugs.php.net/bug.php?id=77218&edit=1

 ID:                 77218
 Comment by:         weirdan at gmail dot com
 Reported by:        magnar at myrtveit dot com
 Summary:            password_hash returns null on failure instead of
                     false as of PHP 7.4
 Status:             Open
 Type:               Documentation Problem
 Package:            *Encryption and hash functions
 PHP Version:        7.3.0
 Block user comment: N
 Private report:     N

 New Comment:

> the behavioral change does not affect PHP 7.3, but master only. 

If there's a behavioral change, it should be mentioned in UPGRADING. 
7.4 branch seems to be missing such a note.


Previous Comments:
------------------------------------------------------------------------
[2019-01-24 19:09:04] cmb@php.net

Correction: the behavioral change does not affect PHP 7.3, but
master only.  The cases which return NULL in PHP 7.3 and before,
are according to the general note regarding return values for
invalid/unsuitable parameters[1].

In my opinion, password_hash() should *throw* on failure for the
same reasons random_bytes() does.

[1] <http://php.net/manual/en/functions.internal.php>

------------------------------------------------------------------------
[2019-01-24 18:45:48] cmb@php.net

I think that might need discussion on internals@.

Anyhow, the status “feedback” is for requesting feedback from the
reporter – if no feedback is given after a week, the ticket will
automatically be closed with status “no feedback”.

------------------------------------------------------------------------
[2019-01-24 18:10:59] girgias@php.net

Is this going to be reverted or should I write a documentation patch?

------------------------------------------------------------------------
[2019-01-02 14:32:38] cmb@php.net

@nikic This is true for master, but the code has recently been
changed[1], and apparently older versions would have returned
FALSE if the underlying hash function failed[2][3]][4]].  So
basically, for PHP ≤ 7.3, the function returned FALSE for a
failing implementation, and NULL for invalid parameters in
combination with a warning (the latter likely according to the
general convention to return NULL on ZPP failures).

This behavioral change looks rather dangerous to me, since
formerly developers who had carefully made sure that they pass
valid arguments might have checked for a FALSE return to signal
failure.  Now they'd get a NULL, which might pass their check.

[1] <https://github.com/php/php-src/commit/534df87c9e3c28001986e70844e0ad04e5708d3d>
[2] <https://github.com/php/php-src/blob/php-7.3.0/ext/standard/password.c#L492>
[3] <https://github.com/php/php-src/blob/php-7.3.0/ext/standard/password.c#L497>
[4] <https://github.com/php/php-src/blob/php-7.3.0/ext/standard/password.c#L585>

------------------------------------------------------------------------
[2019-01-02 13:55:02] nikic@php.net

password_hash() does indeed consistently use null for errors, so this should be adjusted in the
docs, not implementation.

------------------------------------------------------------------------


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