[perl #112962] bad assumption in Perl_reg_temp_copy

# New Ticket Created by  Francois PERRAD 
# Please include the string:  [perl #112962]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org:443/rt3/Ticket/Display.html?id=112962 >


This is a bug report for perl from perrad@cpan.org,
generated with the help of perlbug 1.39 running under perl 5.14.2.


-----------------------------------------------------------------
[Please describe your issue here]
When I update my module re::engine::Lua for Perl 5.12 & 5.14,
qr// segfaults in the function Perl_reg_temp_copy (regcomp.c).
Because this function assumes that the field offs of REGEXP
is always set by the method comp of the regex_engine.
But in re::engine::Lua, offs is set by the method exec.

re::engine::Lua 0.08 includes a workaround,
but I propose a patch.

[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
    category=core
    severity=low
---
Site configuration information for perl 5.14.2:

Configured by Debian Project at Fri Mar 23 17:28:34 UTC 2012.

Summary of my perl5 (revision 5 version 14 subversion 2) configuration:

  Platform:
    osname=linux, osvers=2.6.24-31-server,
archname=i686-linux-gnu-thread-multi-64int
    uname='linux palmer 2.6.24-31-server #1 smp tue feb 14 14:08:16
utc 2012 i686 i686 i386 gnulinux '
    config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN
-Dcccdlflags=-fPIC -Darchname=i686-linux-gnu -Dprefix=/usr
-Dprivlib=/usr/share/perl/5.14 -Darchlib=/usr/lib/perl/5.14
-Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5
-Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local
-Dsitelib=/usr/local/share/perl/5.14.2
-Dsitearch=/usr/local/lib/perl/5.14.2 -Dman1dir=/usr/share/man/man1
-Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1
-Dsiteman3dir=/usr/local/man/man3 -Duse64bitint -Dman1ext=1
-Dman3ext=3perl -Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh
-Ud_ualarm -Uusesfio -Uusenm -Ui_libutil -DDEBUGGING=-g -Doptimize=-O2
-Duseshrplib -Dlibperl=libperl.so.5.14.2 -des'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=define, usemultiplicity=define
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=define, use64bitall=undef, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN
-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include
-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2 -g',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-strict-aliasing
-pipe -fstack-protector -I/usr/local/include'
    ccversion='', gccversion='4.6.3', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=12345678
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
    ivtype='long long', ivsize=8, nvtype='double', nvsize=8,
Off_t='off_t', lseeksize=8
    alignbytes=4, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =' -fstack-protector -L/usr/local/lib'
    libpth=/usr/local/lib /lib/i386-linux-gnu /lib/../lib
/usr/lib/i386-linux-gnu /usr/lib/../lib /lib /usr/lib
    libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
    perllibs=-ldl -lm -lpthread -lc -lcrypt
    libc=, so=so, useshrplib=true, libperl=libperl.so.5.14.2
    gnulibc_version='2.15'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -O2 -g -L/usr/local/lib
-fstack-protector'

Locally applied patches:
>From 84d2d39de77ef762886a6215a787410a5a9563d1 Mon Sep 17 00:00:00 2001
From: Francois Perrad <francois.perrad@gadz.org>
Date: Wed, 16 May 2012 17:55:22 +0200
Subject: [PATCH] copy .offs only if not null.

---
 regcomp.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/regcomp.c b/regcomp.c
index 143f349..c3a258a 100644
--- a/regcomp.c
+++ b/regcomp.c
@@ -12729,7 +12729,6 @@ Perl_reg_temp_copy (pTHX_ REGEXP *ret_x, REGEXP *rx)
 {
     struct regexp *ret;
     struct regexp *const r = (struct regexp *)SvANY(rx);
-    register const I32 npar = r->nparens+1;

     PERL_ARGS_ASSERT_REG_TEMP_COPY;

@@ -12749,8 +12748,11 @@ Perl_reg_temp_copy (pTHX_ REGEXP *ret_x, REGEXP *rx)
     SvLEN_set(ret_x, 0);
     SvSTASH_set(ret_x, NULL);
     SvMAGIC_set(ret_x, NULL);
-    Newx(ret->offs, npar, regexp_paren_pair);
-    Copy(r->offs, ret->offs, npar, regexp_paren_pair);
+    if (r->offs) {
+        const I32 npar = r->nparens+1;
+        Newx(ret->offs, npar, regexp_paren_pair);
+        Copy(r->offs, ret->offs, npar, regexp_paren_pair);
+    }
     if (r->substrs) {
         Newx(ret->substrs, 1, struct reg_substr_data);
 	StructCopy(r->substrs, ret->substrs, struct reg_substr_data);
--
1.7.9.5



---
@INC for perl 5.14.2:
    /etc/perl
    /usr/local/lib/perl/5.14.2
    /usr/local/share/perl/5.14.2
    /usr/lib/perl5
    /usr/share/perl5
    /usr/lib/perl/5.14
    /usr/share/perl/5.14
    /usr/local/lib/site_perl
    .

---
Environment for perl 5.14.2:
    HOME=/home/user
    LANG=en_US.UTF-8
    LANGUAGE=en_US:en
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games
    PERL_BADLANG (unset)
    SHELL=/bin/bash

• [perl #112962] bad assumption in Perl_reg_temp_copy by Francois PERRAD