From @steve-m-hay

Created by @steve-m-hay

I have a problem using the "autouse" pragma which is causing perl
(5.8.4) to crash. I've reduced it to the following two modules​:

Foo.pm

package Foo;
use Exporter qw();
our @​EXPORT = qw(foo);
our @​ISA = qw(Exporter);
sub foo() { require Bar; Bar​::bar() }
1;

Bar.pm

package Bar;
use autouse 'Foo' => qw(foo());
my $done = 0;
sub bar() {
  return if $done;
  $done = 1;
  print "calling foo() once ...\n";
  foo();
  print "... ok\n";
  print "calling foo() again ...\n";
  foo();
  print "... ok\n";
}
1;

Running​:

  >perl -MBar -MFoo -we "Foo​::foo()"

produces the output​:

  calling foo() once ...
  ... ok
  calling foo() again ...

and then perl.exe crashes with an Access Violation. Here's a stacktrace
from the crash (under perl-5.8.4)​:

Perl_pp_entersub() line 2912 + 2 bytes
Perl_runops_standard() line 24 + 3 bytes
S_run_body(long 1) line 1924
perl_run(interpreter * 0x00223c40) line 1840 + 9 bytes
RunPerl(int 5, char * * 0x00223c00, char * * 0x00222ba8) line 202 + 6 bytes
PERL! mainCRTStartup + 227 bytes
KERNEL32! 77e814c7()

The same command-line runs fine, producing the second "... ok" line,
under the "-d" debugger (e.g. perl -d​:ptkdb -MBar -MFoo -we "Foo​::foo()").

I can fix it by reversing the order in which the Foo and Bar modules are
loaded​:

  >perl -MFoo -MBar -we "Foo​::foo()"

or by not loading Bar initially​:

  >perl -MFoo -we "Foo​::foo()"

or by changing the following line within Bar.pm​:

  use autouse 'Foo' => qw(foo());

to either​:

  use autouse 'Foo' => qw(foo);

(!!!) or simply​:

  use Foo;

(understandable).

Flags:
    category=core
    severity=medium

Site configuration information for perl v5.8.4:

Configured by steveh at Mon Apr 26 14:01:56 2004.

Summary of my perl5 (revision 5 version 8 subversion 4) configuration:
  Platform:
    osname=MSWin32, osvers=4.0, archname=MSWin32-x86-perlio
    uname=''
    config_args='undef'
    hint=recommended, useposix=true, d_sigaction=undef
    usethreads=undef use5005threads=undef useithreads=undef 
usemultiplicity=undef
    useperlio=define d_sfio=undef uselargefiles=undef usesocks=undef
    use64bitint=undef use64bitall=undef uselongdouble=undef
    usemymalloc=y, bincompat5005=undef
  Compiler:
    cc='cl', ccflags ='-nologo -Gf -W3 -MD -Zi -DNDEBUG -O1 -DWIN32 
-D_CONSOLE -DNO_STRICT -DHAVE_DES_FCRYPT  -DPERL_DEBUGGING_MSTATS 
-DUSE_PERLIO -DPERL_MSVCRT_READFIX',
    optimize='-MD -Zi -DNDEBUG -O1',
    cppflags='-DWIN32'
    ccversion='', gccversion='', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
    d_longlong=undef, longlongsize=8, d_longdbl=define, longdblsize=10
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', 
lseeksize=4
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='link', ldflags ='-nologo -nodefaultlib -debug -opt:ref,icf  
-libpath:"C:\perl5\lib\CORE"  -machine:x86'
    libpth=C:\PROGRA~1\MICROS~2\VC98\lib
    libs=  oldnames.lib kernel32.lib user32.lib gdi32.lib winspool.lib  
comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib  
netapi32.lib uuid.lib wsock32.lib mpr.lib winmm.lib  version.lib 
odbc32.lib odbccp32.lib msvcrt.lib
    perllibs=  oldnames.lib kernel32.lib user32.lib gdi32.lib 
winspool.lib  comdlg32.lib advapi32.lib shell32.lib ole32.lib 
oleaut32.lib  netapi32.lib uuid.lib wsock32.lib mpr.lib winmm.lib  
version.lib odbc32.lib odbccp32.lib msvcrt.lib
    libc=msvcrt.lib, so=dll, useshrplib=yes, libperl=perl58.lib
    gnulibc_version='undef'
  Dynamic Linking:
    dlsrc=dl_win32.xs, dlext=dll, d_dlsymun=undef, ccdlflags=' '
    cccdlflags=' ', lddlflags='-dll -nologo -nodefaultlib -debug 
-opt:ref,icf  -libpath:"C:\perl5\lib\CORE"  -machine:x86'

Locally applied patches:
    


@INC for perl v5.8.4:
    C:/perl5/lib
    C:/perl5/site/lib
    .


Environment for perl v5.8.4:
    HOME (unset)
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    
PATH=C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\perl5\bin
    PERL_BADLANG (unset)
    SHELL (unset)




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From @nwc10

On Wed, May 19, 2004 at 11​:00​:58AM -0000, Steve Hay wrote​:

I have a problem using the "autouse" pragma which is causing perl
(5.8.4) to crash. I've reduced it to the following two modules​:

$ valgrind --db-attach=yes ./perl -Ilib -MBar -MFoo -we "Foo​::foo()"
==25808== Memcheck, a memory error detector for x86-linux.
==25808== Copyright (C) 2002-2004, and GNU GPL'd, by Julian Seward.
==25808== Using valgrind-2.1.1, a program supervision framework for x86-linux.
==25808== Copyright (C) 2000-2004, and GNU GPL'd, by Julian Seward.
==25808== For more details, rerun with​: -v
==25808==
==25808== Syscall param sigaction(act) contains uninitialised or unaddressable byte(s)
==25808== at 0x3C0F9025​: __libc_sigaction (in /lib/tls/libc-2.3.2.so)
==25808== by 0x7F​: ???
==25808== Address 0x4FFFE980 is on thread 1's stack
==25808==
==25808== ---- Attach to debugger ? --- [Return/N/n/Y/y/C/c] ---- n
calling foo() once ...
... ok
calling foo() again ...
==25808==
==25808== Invalid read of size 1
==25808== at 0x80F3148​: Perl_pp_entersub (pp_hot.c​:2701)
==25808== by 0x80CBDF2​: Perl_runops_debug (dump.c​:1564)
==25808== by 0x80668DF​: S_run_body (perl.c​:1796)
==25808== by 0x8066308​: perl_run (perl.c​:1714)
==25808== Address 0x2C is not stack'd, malloc'd or free'd
==25808==
==25808== ---- Attach to debugger ? --- [Return/N/n/Y/y/C/c] ---- y

...

0x080f3148 in Perl_pp_entersub (my_perl=0x3c20d024) at pp_hot.c​:2701
2701 if (AvREAL(av)) {
(gdb) print av
$1 = (AV *) 0x3c20d6c0
(gdb) print *av
$2 = {sv_any = 0x0, sv_refcnt = 2147483529, sv_flags = 8388608}
(gdb) where
#0 0x080f3148 in Perl_pp_entersub (my_perl=0x3c20d024) at pp_hot.c​:2701
#1 0x080cbdf3 in Perl_runops_debug (my_perl=0x3c20d024) at dump.c​:1564
#2 0x080668e0 in S_run_body (my_perl=0x3c20d024, oldscope=1) at perl.c​:1796
#3 0x08066309 in perl_run (my_perl=0x3c20d024) at perl.c​:1714
#4 0x0805fdc8 in main (argc=6, argv=0x4fffec24, env=0x4fffec40)
  at perlmain.c​:86

2147483529 is 0x7fffff89

I'm not sure where to go next. That first sigaction warning is irritating,
but I don't think that it's relevant.

Nicholas Clark

The RT System itself - Status changed from 'new' to 'open'

From @iabyn

On Sat, May 29, 2004 at 09​:00​:25PM +0100, Nicholas Clark wrote​:

On Wed, May 19, 2004 at 11​:00​:58AM -0000, Steve Hay wrote​:

I have a problem using the "autouse" pragma which is causing perl
(5.8.4) to crash. I've reduced it to the following two modules​:

it can be reduced to the following​:

  $done = 0;
  sub f {
  return if $done;
  $done = 1;
  my $anon = sub { goto &f };
  &$anon;
  f();
  }

  f();

basically the first time f() is called at nested depth 2, its via goto &f,
and asince the caller of the goto was invoked without args (&$anon), an
@​_ array wasn't created at slot 0 in the depth-2 pad.
The next time f() was called convetionally deth 2, there was already
a pad for this depth, but slot 0 contained &PL_sv_undef rather than an AV.

I've fixed it so that goto &f unconditionally creates a new @​_ in slot 0.

Dave.

--
The Enterprise successfully ferries an alien VIP from one place to another
without serious incident.
  -- Things That Never Happen in "Star Trek" #7

Change 22870 by davem@​davem-percy on 2004/05/30 14​:30​:45

  [perl #29708] Problem with autouse (causing Perl to crash)
  @​_ sometimes wasn't getting created right

Affected files ...

... //depot/perl/pad.c#32 edit
... //depot/perl/pp_ctl.c#394 edit
... //depot/perl/t/op/goto.t#22 edit

Differences ...

==== //depot/perl/pad.c#32 (text) ====

@​@​ -1523,6 +1523,9 @​@​
=cut
*/

+/* XXX pad_push is now always called with has_args == 1. Get rid of
+ * this arg at some point */
+
void
Perl_pad_push(pTHX_ PADLIST *padlist, int depth, int has_args)
{

==== //depot/perl/pp_ctl.c#394 (text) ====

@​@​ -2329,7 +2329,7 @​@​
  else {
  if (CvDEPTH(cv) == 100 && ckWARN(WARN_RECURSION))
  sub_crush_depth(cv);
- pad_push(padlist, CvDEPTH(cv), cx->blk_sub.hasargs);
+ pad_push(padlist, CvDEPTH(cv), 1);
  }
  PAD_SET_CUR(padlist, CvDEPTH(cv));
  if (cx->blk_sub.hasargs)

==== //depot/perl/t/op/goto.t#22 (xtext) ====

@​@​ -7,7 +7,7 @​@​
  @​INC = qw(. ../lib);
}

-print "1..32\n";
+print "1..33\n";

require "test.pl";

@​@​ -229,6 +229,19 @​@​
print "not ";
returned_label : print "ok 32 - done to returned_label\n";

+# [perl #29708] - goto &foo could leave foo() at depth two with
+# @​_ == PL_sv_undef, causing a coredump
+
+
+my $r = runperl(
+ prog =>
+ 'sub f { return if $d; $d=1; my $a=sub {goto &f}; &$a; f() } f(); print qq(ok\n)',
+ stderr => 1
+ );
+print "not " if $r ne "ok\n";
+print "ok 33 - avoid pad without an \@​_\n";
+
+
exit;

bypass​:

@iabyn - Status changed from 'open' to 'resolved'