PHP 8.4.17 RC 1: #71527 Buffer over-write in finfo_open with malformed magic file

[ArchMaster2024]

Description

The following code:

    $finfo = finfo_open(FILEINFO_NONE, __DIR__ . DIRECTORY_SEPARATOR . "bug71527私はガラスを食べられます.magic");
    var_dump($finfo);
<?php

Resulted in this output:

Warning: finfo_open(/test_php/source/php/ext/fileinfo/tests/bug71527私はガラスを食べられます.magic): Failed to open stream: No such file or directory in /test_php/source/php/ext/fileinfo/tests/bug71527-mb.php on line 2

Warning: finfo_open(/test_php/source/php/ext/fileinfo/tests/bug71527私はガラスを食べられます.magic): Failed to open stream: No such file or directory in /test_php/source/php/ext/fileinfo/tests/bug71527-mb.php on line 2

Warning: finfo_open(): Failed to load magic database at "/test_php/source/php/ext/fileinfo/tests/bug71527私はガラスを食べられます.magic" in /test_php/source/php/ext/fileinfo/tests/bug71527-mb.php on line 2
bool(false)

But I expected this output instead:

Warning: finfo_open(): Failed to load magic database at "%sbug71527私はガラスを食べられます.magic" in %sbug71527-mb.php on line %d
bool(false)

PHP Version

PHP 8.4.17RC1 (cli) (built: Jan 25 2026 21:18:17) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.4.17RC1, Copyright (c) Zend Technologies

Operating System

Debian GNU/Linux 12 (bookworm) x86_64 (container run with podman)

[ndossche]

It will give the right output if you place this file in ext/fileinfo/tests. I also don't see any buffer overwrite. Could you please clarify?

[ArchMaster2024]

I don't have an idea of I need to put that file on that location, I simply compile rc version and run test suite and see that fail and report it. I show you the messages I get when I run the test suite.

I made a mistake in reporting this, if that's the case, I'm really sorry, I have no idea this was misreported or not, I just saw that they gave me the errors and came to report it.

[iluuu1994]

The diff is not clear from your screenshot. Can you upload the result file?

[ArchMaster2024]

php_test_results_20260125_2121.txt

That's the file I get it after run make TEST_PHP_ARGS=-j8 test.