ID: 36267
User updated by: mikeb at tracersinfo dot com
Reported By: mikeb at tracersinfo dot com
-Status: Feedback
+Status: Open
Bug Type: PCRE related
Operating System: Linux
PHP Version: 5.1.2
New Comment:
I recompiled PHP 5.1.2 with --enable-debug added to my config options
on my home machine from the available sources on your site. Despite
this, I wasn't able to get a core file as described in your
documentation on backtrace. However, running the CLI under gdb, I did
get the following:
-------------------------------------
(gdb) run testpregfault2.txt
Starting program: /usr/local/bin/php testpregfault2.txt
[Thread debugging using libthread_db enabled]
[New Thread -1215732032 (LWP 18908)]
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -1215732032 (LWP 18908)]
0x080a293c in match (
eptr=0x85f480f "vv wwwww xxxxx yyyyy zzzzz\naaaaa bbbbb ccccc ddddd
eeeee fffff ggggg <hhh> iiiii jjjjj kkkkk lllll mmmmm\nnnnnn ooooo ppppp
qqqqq rrrrr sssss ttttt uuuuu vvvvv wwwww xxxxx yyyyy zzzzz\naaaaa bbbbb
ccccc"...,
ecode=0x858121a "\027<A", offset_top=2, md=0xbfb7d274, ims=5,
eptrb=0xbf3803d0, flags=2)
at /home/mikeb/src/php-5.1.2/ext/pcre/pcrelib/pcre_exec.c:357
357 {
--------------------------------------
Attempts to bt from here yielded thousands (I killed it sometime after
5000) frames similar to:
---------------------------------------
#5835 0x080a67bd in match (
eptr=0x85f3145 "llll mmmmm\nnnnnn ooooo ppppp qqqqq rrrrr sssss
ttttt uuuuu vvvvv wwwww xxxxx yyyyy zzzzz\naaaaa bbbbb ccccc ddddd
eeeee fffff ggggg <hhh> iiiii jjjjj kkkkk lllll mmmmm\nnnnnn ooooo
ppppp qqqqq rrrrr sss"...,
ecode=0x8581217 "J", offset_top=2, md=0xbfb7d274, ims=5,
eptrb=0xbf726970,
flags=Variable "flags" is not available.
) at /home/mikeb/src/php-5.1.2/ext/pcre/pcrelib/pcre_exec.c:975
--------------------------------
with the subject string growing one character at a time to the left
(next was 'lllll', etc.)
The final commands listed at the bottom of your "generating a gdb
backtrace" page yielded the following results:
----------------------------
(gdb) print (char
*)(executor_globals.function_state_ptr->function)->common.function_name
$1 = 0x8372d23 "preg_replace"
(gdb) print (char *)executor_globals.active_op_array->function_name
$2 = 0x0
(gdb) print (char *)executor_globals.active_op_array->filename
$3 = 0x8584bfc "/home/mikeb/temp/testpregfault2.txt"
-----------------------------------------
I'll be happy to do anything I can to give you more information on
this, but there's no telling how many more thousands of match() frames
there were, and it seems pretty clear that the last execute() was
preg_replace.
Frankly, I'm most puzzled by the fact that this works properly on every
Windows machine I've tried it on, and fails consistently identically on
at least three separately-compiled Linux machines.
Thanks for your help.
Mike
Previous Comments:
------------------------------------------------------------------------
[2006-02-02 21:18:48] [EMAIL PROTECTED]
Thank you for this bug report. To properly diagnose the problem, we
need a backtrace to see what is happening behind the scenes. To
find out how to generate a backtrace, please read
http://bugs.php.net/bugs-generating-backtrace.php for *NIX and
http://bugs.php.net/bugs-generating-backtrace-win32.php for Win32
Once you have generated a backtrace, please submit it to this bug
report and change the status back to "Open". Thank you for helping
us make PHP better.
This is all I can get with valgrind and I can't reproduce the segfault
without it.
==3882== Process terminating with default action of signal 11
(SIGSEGV)
==3882== Access not within mapped region at address 0xBE7FFF24
==3882== at 0x806D2FD: match (pcre_exec.c:517)
==3882== Stack overflow in thread 1: can't grow stack to 0xBE7FFEAC
------------------------------------------------------------------------
[2006-02-02 21:15:49] [EMAIL PROTECTED]
the url you refer above doesn't work (error 403). please change the
permissions.
------------------------------------------------------------------------
[2006-02-02 21:06:42] mikeb at tracersinfo dot com
Description:
------------
I use PCRE's every day to harvest information from webpages (i.e., not
a newbie, and I use many very complex expressions regularly).
I recently ran into a problem with an expression I needed to use
(essentially, to select a particular <table>, its contents, and
everything that follows it on page full of tables -- specifically
without allowing an intervening <table> or </table> tag) that worked
perfectly throughout my development under Windows XP Home SP2. As soon
as I ported the script to GNU/Linux (3 different machines: Mandrake 10
[2.6.8 kernel]; 2 Ubuntu 5.10 [2.6.12 kernel]), it segfaults both under
the CLI and Apache (1.3.33) SAPI. (The use of once-only subpattern is
not significant -- same result is obtained using merely non-matching
subpattern.)
I've simplified the referenced script to what it takes to reproduce the
problem, and I note that significant reduction in size of the two <tag>
sections can allow this to function properly under Linux, but I do not
have that luxury with arbitrary incoming webpages that must be parsed
without advance knowledge of their contents.
The same symptom obtains if I attempt to use preg_match instead of
preg_replace.
One of the failing PHP's config lines: --disable-cgi
--with-apxs=/www/bin/apxs --enable-magic-quotes --with-openssl
--with-zlib --enable-bcmath --with-bz2 --enable-calendar --with-curl
--with-curlwrappers --enable-ftp --with-gd --with-mysql --with-mysqli
--with-pdo-mysql --with-readline --enable-soap --enable-sockets
--with-xsl
Fails with stock php.ini-dist.
Reproduce code:
---------------
http://home.tampabay.rr.com/greenorb/testpregfault2.txt
Expected result:
----------------
I expect to see the first <tag> tag echoed to my screen with a legend
that "Stripfootpat worked". (Note that this IS the result obtained
under Win32 [Windows XP Pro/Home SP2].)
Actual result:
--------------
Segmentation fault
------------------------------------------------------------------------
--
Edit this bug report at http://bugs.php.net/?id=36267&edit=1
