Perl segfault w/ specific weird syntax.

[p5pRT]

Migrated from rt.perl.org#1816 (status was 'resolved')

Searchable as RT1816$

[p5pRT]

From @raindrift

I'm getting a segfault under a particular little strange condition. The
smallest bit of code I've managed to reproduce it with is as follows​:

my $var1 = '';
my $var2 = '';
@​arr1 = qw( );
sub

If you save that in a file, let's call it bug.pl, and then execute​:

perl -e "require 'bug.pl'"

you'll get a segfault (or, at least, I do). If you just execute it, it's
fine.

The perl syntax here is obviously incorrect, but finding the bit that's
incorrect without any real error messages is a bit vexing. Of course, this
isn't a big deal, but if one's just hunting for things to fix... :)

For some reason, the perl distributed with RH6 doesn't seem to have perlbug
with it, so here's the output from perl -V, and below it you'll find a stack
trace of the core file (c/o gdb)​:

Summary of my perl5 (5.0 patchlevel 5 subversion 3) configuration​:
  Platform​:
  osname=linux, osvers=2.2.1-ac1, archname=i386-linux
  uname='linux porky.devel.redhat.com 2.2.1-ac1 #1 smp mon feb 1 17​:44​:44 est 1999 i686 unknown '
  hint=recommended, useposix=true, d_sigaction=define
  usethreads=undef useperlio=undef d_sfio=undef
  Compiler​:
  cc='cc', optimize='-O2', gccversion=egcs-2.91.66 19990314/Linux (egcs-1.1.2 release)
  cppflags='-Dbool=char -DHAS_BOOL -I/usr/local/include'
  ccflags ='-Dbool=char -DHAS_BOOL -I/usr/local/include'
  stdchar='char', d_stdstdio=undef, usevfork=false
  intsize=4, longsize=4, ptrsize=4, doublesize=8
  d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
  alignbytes=4, usemymalloc=n, prototype=define
  Linker and Libraries​:
  ld='cc', ldflags =' -L/usr/local/lib'
  libpth=/usr/local/lib /lib /usr/lib
  libs=-lnsl -lndbm -lgdbm -ldb -ldl -lm -lc -lposix -lcrypt
  libc=, so=so, useshrplib=false, libperl=libperl.a
  Dynamic Linking​:
  dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynamic'
  cccdlflags='-fpic', lddlflags='-shared -L/usr/local/lib'

Characteristics of this binary (from libperl)​:
  Built under linux
  Compiled at Apr 6 1999 23​:34​:07
  @​INC​:
  /usr/lib/perl5/5.00503/i386-linux
  /usr/lib/perl5/5.00503
  /usr/lib/perl5/site_perl/5.005/i386-linux
  /usr/lib/perl5/site_perl/5.005
  .

And the stack trace​:

#0 0x806f73f in Perl_pad_free ()
#1 0x806f903 in Perl_op_free ()
#2 0x806f7fa in Perl_op_free ()
#3 0x806f7fa in Perl_op_free ()
#4 0x809fe67 in Perl_sv_compile_2op ()
#5 0x80a08a1 in Perl_pp_require ()
#6 0x80b148d in Perl_runops_standard ()
#7 0x80592b8 in perl_run ()
#8 0x805782f in main ()
#9 0x400a5cb3 in __libc_start_main (main=0x80577c0 <main>, argc=3,
  argv=0xbffff8b4, init=0x8056af4 <_init>, fini=0x80b14fc <_fini>,
  rtld_fini=0x4000a350 <_dl_fini>, stack_end=0xbffff8ac)
  at ../sysdeps/generic/libc-start.c​:78

Thanks!
-Ian

[p5pRT]

From @andk

On Tue, 23 Nov 1999 00​:12​:13 -0600, Ian Baker <ian@​sonic.net> said​:

Hi. I'm running Perl, version 5.005_03 built for i386-linux

I'm getting a segfault under a particular little strange condition. The
smallest bit of code I've managed to reproduce it with is as follows​:

my $var1 = '';
my $var2 = '';
@​arr1 = qw( );
sub

If you save that in a file, let's call it bug.pl, and then execute​:

perl -e "require 'bug.pl'"

Confirmed for current snapshot of perl5.005_62+. Can be reduced to

perl -e '
eval q{my $var1 = "";
my $var2 = "";
@​arr1 = qw();
sub};
'

As I have a debugging perl here, I'll add my stack trace​:

(gdb) bt
#0 0x8080eb2 in Perl_pad_free (po=4) at op.c​:508
#1 0x80812dd in S_op_clear (o=0x813c448) at op.c​:786
#2 0x8081109 in Perl_op_free (o=0x813c448) at op.c​:685
#3 0x80810ae in Perl_op_free (o=0x813c088) at op.c​:673
#4 0x80810ae in Perl_op_free (o=0x813c508) at op.c​:673
#5 0x80eaca7 in S_doeval (gimme=0, startop=0x0) at pp_ctl.c​:2635
#6 0x80ec829 in Perl_pp_require () at pp_ctl.c​:3010
#7 0x80aea4b in Perl_runops_debug () at run.c​:56
#8 0x805b951 in S_run_body (args=0xbffffaec) at perl.c​:1201
#9 0x80de113 in Perl_vdefault_protect (pcur_env=0xbffffb00, excpt=0xbffffbb0,
  body=0x805b7e0 <S_run_body>, args=0xbffffacc) at scope.c​:45
#10 0x80de029 in Perl_default_protect (pcur_env=0xbffffb00, excpt=0xbffffbb0,
  body=0x805b7e0 <S_run_body>) at scope.c​:26
#11 0x805b563 in perl_run (my_perl=0x812ec08) at perl.c​:1134
#12 0x805898f in main (argc=3, argv=0xbffffbe4, env=0xbffffbf4)
  at perlmain.c​:53

--
andreas

Summary of my perl5 (revision 5.0 version 5 subversion 63) configuration​:
  Platform​:
  osname=linux, osvers=2.2.12, archname=i586-linux
  uname='linux hohenstaufen.in-berlin.de 2.2.12 #2 smp sat oct 2 11​:10​:42 cest 1999 i586 unknown '
  config_args='-Dprefix=/sources-perl/inst/perl5.005_62..4590g -Doptimize=-g -des -Dusemymalloc'
  hint=recommended, useposix=true, d_sigaction=define
  usethreads=undef useperlio=undef d_sfio=undef
  use64bits=undef usemultiplicity=undef
  Compiler​:
  cc='cc', optimize='-g', gccversion=2.7.2.3
  cppflags='-Dbool=char -DHAS_BOOL -DDEBUGGING -I/usr/local/include'
  ccflags ='-Dbool=char -DHAS_BOOL -DDEBUGGING -I/usr/local/include'
  stdchar='char', d_stdstdio=define, usevfork=false
  intsize=4, longsize=4, ptrsize=4, doublesize=8
  d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
  alignbytes=4, usemymalloc=y, prototype=define
  Linker and Libraries​:
  ld='cc', ldflags =' -L/usr/local/lib'
  libpth=/usr/local/lib /lib /usr/lib
  libs=-lnsl -lndbm -lgdbm -ldb -ldl -lm -lc -lposix -lcrypt
  libc=/lib/libc-2.0.7.so, so=so, useshrplib=false, libperl=libperl.a
  Dynamic Linking​:
  dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynamic'
  cccdlflags='-fpic', lddlflags='-shared -L/usr/local/lib'

Characteristics of this binary (from libperl)​:
  Compile-time options​: DEBUGGING
  Built under linux
  Compiled at Nov 18 1999 16​:24​:18
  @​INC​:
  /sources-perl/inst/perl5.005_62..4590g/lib/5.00563/i586-linux
  /sources-perl/inst/perl5.005_62..4590g/lib/5.00563
  /sources-perl/inst/perl5.005_62..4590g/lib/site_perl/5.00563/i586-linux
  /sources-perl/inst/perl5.005_62..4590g/lib/site_perl
  .