Bug #73483 [Com]: Segmentation fault
Edit report at https://bugs.php.net/bug.php?id=73483&edit=1
ID: 73483
Comment by: alex at buayacorp dot com
Reported by: alex at buayacorp dot com
Summary: Segmentation fault
Status: Verified
Type: Bug
Package: PCRE related
Operating System: debian wheezy
PHP Version: 7.0.12
Assigned To: dmitry
Block user comment: N
Private report: N
New Comment:
I added a naive patch that uses a combination of regex+locale (if available) which seems to fix this
issue.
Previous Comments:
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[2016-11-10 15:30:31] alex at buayacorp dot com
After looking a little bit more into this issue I think this happens because the update logic of
already cached items doesn't really take into account locale changes.
For example, if a regex A was cached with locale X, then pcre_get_compiled_regex_cache
will store it as H(x, compiled(A)). If this cached value is still in use (i.e.
preg_replace_callback in the provided script) AND the locale changes to Y, then
pcre_get_compiled_regex_cache will update the entry H(x, compiled(B)) (via
zend_hash_update_mem), this will override the refere that's still in use for H(x,
compiled(A)).
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[2016-11-09 15:33:35] cmb@php.net
This issue is apparently locale related. For instance, the script works
fine if the locale is "C", see <https://3v4l.org/4IVgb>. Alternatively,
commenting out line 58[1] will also let the script succeed.
Anyhow, the behavioral change had been introduced with commit
4514ba01[2].
Dmitry, can you please have a look at this issue?
[1] <https://gist.github.com/xknown/b0bdcfa87edf039e995822d86cfde441#file-segfault-php-L58>
[2] <http://git.php.net/?p=php-src.git;a=commit;h=4514ba016ff158cd113deef1a215fcdcb6913b48>
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[2016-11-09 12:06:47] alex at buayacorp dot com
Description:
------------
We've noticed a few segmentation faults in some of our servers. I am able to consistently
reproduce it in a debian wheezy vm with the test script below.
alex@atoq-wheezy:~/php-7.0.12$ uname -a
Linux atoq-wheezy 3.2.0-4-amd64 #1 SMP Debian 3.2.82-1 x86_64 GNU/Linux
alex@atoq-wheezy:~/php-7.0.12$ locale
LANG=en_US.UTF-8
LANGUAGE=en_US:en
LC_CTYPE="en_US.UTF-8"
LC_NUMERIC="en_US.UTF-8"
LC_TIME="en_US.UTF-8"
LC_COLLATE="en_US.UTF-8"
LC_MONETARY="en_US.UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_PAPER="en_US.UTF-8"
LC_NAME="en_US.UTF-8"
LC_ADDRESS="en_US.UTF-8"
LC_TELEPHONE="en_US.UTF-8"
LC_MEASUREMENT="en_US.UTF-8"
LC_IDENTIFICATION="en_US.UTF-8"
LC_ALL=
# PHP compiled with --disable-all flag.
alex@atoq-wheezy:~/php-7.0.12$ sapi/cli/php -v
PHP 7.0.12 (cli) (built: Nov 9 2016 11:29:49) ( NTS )
Copyright (c) 1997-2016 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies
The script works fine in the same VM under PHP 5.6.27.
# PHP compiled with --disable-all flag.
alex@atoq-wheezy:~/php-5.6.27$ sapi/cli/php ../segfault.php
string(22) "<p>hola</p><p>hola</p>"
Test script:
---------------
https://gist.github.com/xknown/b0bdcfa87edf039e995822d86cfde441
Expected result:
----------------
string(22) "<p>hola</p><p>hola</p>"
Actual result:
--------------
alex@atoq-wheezy:~/php-7.0.12$ sapi/cli/php -dpcre.jit=0 ../segfault.php
NULL
alex@atoq-wheezy:~/php-7.0.12$ sapi/cli/php -dpcre.jit=1 ../segfault.php
NULL
Segmentation fault
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