Regex times out and crashes Apache when pcre.jit is enabled

[JackJohansson]

Recently I've installed PHP8.1.0RC6 and Laravel 9 to try out some of the new features. I was unable to load any pages using Laravel, as Apache would crash and I would get a connection reset message.

I've posted a bug report on Laravel's repository here. We've tracked down the issue to a regex. I was suggested to post the bug on php.net, which I did submit. After further investigation, it appears that the issue is related to a recent patch to this repository.

The detailed bug description can be found in the links below, but just as a short explanation, the following piece of code will crash Apache ( using 2.4.51 ) when pcre.jit = 1 but does not cause a problem when it's executed via CLI:

var_dump(
	preg_match(
		'(([\\r\\n]{1,1000})|([^\\S\\r\\n]{1,1000})|(\\\\)|(\')|(")|(\\#)|(\\$)|(([^(\\s\\\\\'"\\#\\$)]|\\(|\\)){1,1000}))A',
		'Laravel',
		$matches
	)
);

Bug report on Laravel repository:
laravel/framework#39716

Bug report on bugs.php.net:
https://bugs.php.net/bug.php?id=81647

[zherczeg]

Thank you for the report. There was a follow-up fix for that: 51ec2c9
Is this fix your issue?

[JackJohansson]

Thanks for the quick response! Unfortunately I don't have the tools to compile the latest version on Windows, so I'll wait a few days for the new PHP release, which most likely has PCRE 10.39 bundled :)

[cmb69]

@zherczeg, PHP already has that patch applied (php/php-src@788a701), but the stack overflow occurs nonetheless. I'll try with a clean PCRE2 10.39, and report back.

@JackJohansson, it is rather unlikely that PHP 8.1.0 will ship with PCRE2 10.39. It is still on a slightly patched 10.37, and 8.1.0 is going to be tagged today.

[cmb69]

I'll try with a clean PCRE2 10.39, and report back.

Same issue, namely a stack overflow during compilation.

[zherczeg]

Hm, it looks like when I updated the code I changed a != to ==
0dd0283 line 1619

[zherczeg]

Please check if #58 fixes the issue. I am doing too many typos these days.

[cmb69]

Yes, that fixes the issue (and the rest of PHP's pcre test suite still passes). Thank you!

[zherczeg]

@PhilipHazel if you are ok with this patch, please land it. Thank you.

[PhilipHazel]

I have done the merge of #58.