[perl #24382] qr((??{})) causes runaway perl process

# New Ticket Created by  D Wollmann 
# Please include the string:  [perl #24382]
# in the subject line of all future correspondence about this issue. 
# <URL: http://rt.perl.org/rt2/Ticket/Display.html?id=24382 >


This is a bug report for perl from boss@thumper.puttybox.local,
generated with the help of perlbug 1.34 running under perl v5.8.0.


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[Please enter your report here]

Recursive regular expression definition using qr// expression with
paren delimiters and a postponed regular subexpression (??{})
causes the perl process to run away, consuming resources until
OOM kill.

$p = qr/(??{$p})/x; /$p/        # works as expected

$p = qr((??{$p}))x; /$p/        # causes a runaway perl

This behavior occurs with perl versions 5.6.0, 5.6.1 and 5.8.0.

Limiting the user's stack size via ulimit -s 8192 (for example)
prevents the runaway, resulting in a segfault instead.


[Please do not change anything below this line]
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---
Flags:
    category=core
    severity=medium
---
Site configuration information for perl v5.8.0:

Configured by boss at Tue Jul 29 00:56:33 CDT 2003.

Summary of my perl5 (revision 5.0 version 8 subversion 0) configuration:
  Platform:
    osname=linux, osvers=2.4.20-gentoo-r5, archname=i686-linux
    uname='linux thumper 2.4.20-gentoo-r5 #1 tue may 20 00:25:16 cdt 2003 i686 
pentium iii (coppermine) genuineintel gnulinux '
    config_args='-des -Darchname=i686-linux -Dcc=gcc -Dprefix=/usr 
-Dvendorprefix=/usr -Dsiteprefix=/usr -Dlocincpth=  
-Doptimize=-march=pentium3 -O3 -pipe -Duselargefiles -Dd_dosuid 
-Dd_semctl_semun -Dscriptdir=/usr/bin -Dman3ext=3pm -Dcf_by=Gentoo -Ud_csh 
-Di_gdbm -Di_db -Di_ndbm'
    hint=recommended, useposix=true, d_sigaction=define
    usethreads=undef use5005threads=undef useithreads=undef 
usemultiplicity=undef
    useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
    use64bitint=undef use64bitall=undef uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='gcc', ccflags ='-DPERL5 -fno-strict-aliasing -D_LARGEFILE_SOURCE 
-D_FILE_OFFSET_BITS=64',
    optimize='-march=pentium3 -O3 -pipe',
    cppflags='-DPERL5 -DPERL5 -fno-strict-aliasing'
    ccversion='', gccversion='3.2.2', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', 
lseeksize=8
    alignbytes=4, prototype=define
  Linker and Libraries:
    ld='gcc', ldflags =' -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib
    libs=-lpthread -lnsl -lndbm -lgdbm -ldb -ldl -lm -lc -lcrypt -lutil
    perllibs=-lpthread -lnsl -ldl -lm -lc -lcrypt -lutil
    libc=/lib/libc-2.3.1.so, so=so, useshrplib=false, libperl=libperl.a
    gnulibc_version='2.3.1'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynamic'
    cccdlflags='-fpic', lddlflags='-shared -L/usr/local/lib'

Locally applied patches:
    

---
@INC for perl v5.8.0:
    /home/boss/perllib
    /etc/perl
    /usr/lib/perl5/site_perl/5.8.0/i686-linux
    /usr/lib/perl5/site_perl/5.8.0
    /usr/lib/perl5/site_perl/5.6.1
    /usr/lib/perl5/site_perl
    /usr/lib/perl5/vendor_perl/5.8.0/i686-linux
    /usr/lib/perl5/vendor_perl/5.8.0
    /usr/lib/perl5/vendor_perl
    /usr/lib/perl5/5.8.0/i686-linux
    /usr/lib/perl5/5.8.0
    /usr/local/lib/site_perl
    /usr/lib/perl5/site_perl/5.6.1
    .

---
Environment for perl v5.8.0:
    HOME=/home/boss
    LANG=en_US
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    
PATH=/home/boss/bin:/bin:/usr/bin:/usr/local/bin:/opt/bin:/usr/i686-pc-linux-gnu/gcc-bin/3.2:/opt/Acrobat5:/usr/X11R6/bin:/opt/sun-jdk-1.4.2.01/bin:/opt/sun-jdk-1.4.2.01/jre/bin:/opt/sun-jdk-1.4.2.01/jre/javaws:/usr/qt/3/bin:/usr/kde/3.1/bin:/usr/kde/3.1/bin:/usr/qt/2/bin:/usr/kde/3/bin:/usr/games/bin:/opt/sun-jdk-1.4.2.01/bin:/opt/sun-jdk-1.4.2.01/jre/bin:/opt/sun-jdk-1.4.2.01/jre/javaws
    PERL5LIB=/home/boss/perllib
    PERL5TESTLIB=/home/boss/perltestlib
    PERL_BADLANG (unset)
    SHELL=/bin/bash

• [perl #24382] qr((??{})) causes runaway perl process by D Wollmann
• Re: [perl #24382] qr((??{})) causes runaway perl process by Slaven Rezic
• Re: [perl #24382] qr((??{})) causes runaway perl process by David Wollmann