Bug#545234: segfault with s/(.)\G//g

[Niko Tyni]

This is a bug report for perl from Niko Tyni <ntyni at debian.org>,
generated with the help of perlbug 1.39 running under perl 5.11.0.


-----------------------------------------------------------------
As reported by Raphael Geissert in <http://bugs.debian.org/545234>:

$ echo foo | perl -pe "s/(.)\G//g"

crashes on 5.10.0, 5.10.1 and current blead.

Backtrace:

Core was generated by `./miniperl -pe s/(.)\G//g'.
Program terminated with signal 11, Segmentation fault.
[New process 30959]
#0  0x00007f970786761e in _wordcopy_bwd_aligned () from /lib/libc.so.6
(gdb) bt
#0  0x00007f970786761e in _wordcopy_bwd_aligned () from /lib/libc.so.6
#1  0x00007f9707866422 in memmove () from /lib/libc.so.6
#2  0x0000000000540cc0 in Perl_sv_catpvn_flags (my_perl=0x12c1010, dsv=0x12e3688, sstr=0x12dcde8 "", 
    slen=18446744073709551615, flags=2) at sv.c:4732
#3  0x000000000050d08f in Perl_pp_subst (my_perl=0x12c1010) at pp_hot.c:2319
#4  0x00000000004b3b64 in Perl_runops_debug (my_perl=0x12c1010) at dump.c:2044
#5  0x00000000006f4964 in S_run_body (my_perl=0x12c1010, oldscope=1) at perlmini.c:2286
#6  0x00000000006f3c80 in perl_run (my_perl=0x12c1010) at perlmini.c:2211
#7  0x00000000006c5c52 in main (argc=3, argv=0x7fff10631fb8, env=0x7fff10631fd8) at miniperlmain.c:117


-----------------------------------------------------------------
---
Flags:
    category=core
    severity=low
---
Site configuration information for perl 5.11.0:

Configured by Debian Project at Tue Sep  8 09:40:07 EEST 2009.

Summary of my perl5 (revision 5 version 11 subversion 0) configuration:
  Commit id: d1ce36d727ed53b12332c6ef40743b21335b21a1
  Platform:
    osname=linux, osvers=2.6.26-2-openvz-amd64, archname=x86_64-linux-gnu-thread-multi
    uname='linux minerva 2.6.26-2-openvz-amd64 #1 smp wed aug 19 23:15:49 utc 2009 x86_64 gnulinux '
    config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN -Dcccdlflags=-fPIC -Darchname=x86_64-linux-gnu -Dprefix=/usr -Dprivlib=/usr/share/perl/5.11 -Darchlib=/usr/lib/perl/5.11 -Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.11.0 -Dsitearch=/usr/local/lib/perl/5.11.0 -Dman1dir=/usr/share/man/man1 -Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1 -Dsiteman3dir=/usr/local/man/man3 -Dman1ext=1 -Dman3ext=3perl -Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Ud_ualarm -Uusesfio -Uusenm -DDEBUGGING=both -Doptimize=-O2 -O0 -Dusedevel -Uuseshrplib -des'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=define, usemultiplicity=define
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=define, use64bitall=define, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -DDEBUGGING -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2 -O0 -g',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -DDEBUGGING -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include'
    ccversion='', gccversion='4.3.2', gccosandvers=''
    intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
    ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =' -fstack-protector -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib /lib64 /usr/lib64
    libs=-lgdbm -ldb -ldl -lm -lcrypt -lpthread -lc -lgdbm_compat
    perllibs=-ldl -lm -lcrypt -lpthread -lc
    libc=/lib/libc-2.7.so, so=so, useshrplib=false, libperl=libperl.a
    gnulibc_version='2.7'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -O2 -O0 -g -L/usr/local/lib -fstack-protector'

Locally applied patches:
    

---
@INC for perl 5.11.0:
    lib
    /usr/local/lib/perl/5.11.0
    /usr/local/share/perl/5.11.0
    /usr/lib/perl5
    /usr/share/perl5
    /usr/lib/perl/5.11
    /usr/share/perl/5.11
    .

---
Environment for perl 5.11.0:
    HOME=/home/niko
    LANG=en_US.UTF-8
    LANGUAGE (unset)
    LC_CTYPE=fi_FI.UTF-8
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/niko/bin:/home/niko/bin:/home/niko/bin:/usr/local/bin:/usr/bin:/bin:/usr/games:/sbin:/usr/sbin
    PERL_BADLANG (unset)
    SHELL=/bin/zsh