Bug #71659 [Com]: segmentation fault in pcre running twig tests

From: Date: Tue, 08 Mar 2016 23:00:40 +0000
Subject: Bug #71659 [Com]: segmentation fault in pcre running twig tests
References: 1  Groups: php.bugs 
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Edit report at https://bugs.php.net/bug.php?id=71659&edit=1

 ID:                 71659
 Comment by:         nish dot aravamudan at canonical dot com
 Reported by:        nish dot aravamudan at canonical dot com
 Summary:            segmentation fault in pcre running twig tests
 Status:             Open
 Type:               Bug
 Package:            Reproducible crash
 Operating System:   Ubuntu 16.04
 PHP Version:        7.0.3
 Block user comment: N
 Private report:     N

 New Comment:

If I understand this right, that should rather be:

+       extra->mark = NULL;


Previous Comments:
------------------------------------------------------------------------
[2016-03-08 22:48:35] nish dot aravamudan at canonical dot com

I'm going to test a new version of PHP7.0 that has a small adjustment to php_

--- php7.0-7.0.3.orig/ext/pcre/php_pcre.c
+++ php7.0-7.0.3/ext/pcre/php_pcre.c
@@ -1761,6 +1761,7 @@ PHPAPI void php_pcre_split_impl(pcre_cac
        extra->match_limit = (unsigned long)PCRE_G(backtrack_limit);
        extra->match_limit_recursion = (unsigned long)PCRE_G(recursion_limit);
 #ifdef PCRE_EXTRA_MARK
+       extra->mark = &mark;
        extra->flags &= ~PCRE_EXTRA_MARK;
 #endif


Commit https://github.com/php/php-src/commit/376ab3b7873ca04142185d8c08dbb4c4be152474
(and presumably others based upon the current state of the code) modified the other functions to
avoid ->mark corruption. I don't know why this only shows up with JIT, but perhaps the
->mark value is not clobbered except if JIT is used.

------------------------------------------------------------------------
[2016-03-02 21:22:39] inefedor at gmail dot com

Probably when phpunit runs tests in different process, it uses another php binary or another set of
php.ini settings.

------------------------------------------------------------------------
[2016-03-02 16:45:14] nish dot aravamudan at canonical dot com

https://bugs.exim.org/show_bug.cgi?id=1803
filed.

However, two updates from my testing last night.

1) The twig testsuite is run using phpunit. phpunit has a parameter --process-isolation. When the
tests are run with that parameter, the tests pass (even with pcre.jit left on). This, I think,
points to a PHP bug, but I'm not sure.

2) When I tried to just run the failing twig tests on their own (split_utf8.test and
length_utf8.test are the two input files), I could not recreate the segmentation fault. This again,
it feels like, points to a fault somewhere in the php logic due to some corrupt state, perhaps?

------------------------------------------------------------------------
[2016-02-28 08:38:43] pajoye@php.net

One of the JIT bugs in pcre. It should be reported upstream.

------------------------------------------------------------------------
[2016-02-26 21:34:38] nish dot aravamudan at canonical dot com

Adding pcre.jit=0 to the invocation of the tests (-d parameter to phpunit) allows the test to
succeed.

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


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