From @steve-m-hay

The following program (put together by Matthew Horsfall (alh) <wolfsage@​gmail.com> in the course of investigating rt.perl.org#124048) SEGVs after hitting deep recursion in the tied hash FIRSTKEY subroutine​:

#!/usr/bin/perl

use strict;
use warnings;

{
  package Tied​::Thingy;
  require Tie​::Hash;

  our @​ISA = qw(Tie​::StdHash);

  sub FIRSTKEY {
  my $self = shift;
  return keys %{ $self->{parent} };
  }
}

my %x;
tie %x, 'Tied​::Thingy';
$x{parent} = \%x;

for my $k (keys %x) {
  print "K​: $k\n";
}

The original bug report was ultimately a case of garbage-in, garbage-out, but I'm logging the SEGV here on the basis that any crash in perl is surely a bug.

From @bulk88

On Tue Mar 17 15​:50​:59 2015, shay wrote​:

The original bug report was ultimately a case of garbage-in, garbage-
out, but I'm logging the SEGV here on the basis that any crash in perl
is surely a bug.

With that script.

"Unhandled exception at 0x77ef5bf1 (ntdll.dll) in perl.exe​: 0xC00000FD​: Stack overflow."

Only ~7 MB of memory is being used by the process but vmmap shows the process ran out of C stack (see pic).

unpack('P1', "\x01\x00\x00\x00") or unpack('P1', "\x01\x00\x00\x00\x00\x00\x00\x00") also crashes, is that a bug? I dont think running out of C stack on deep recursion (unless the bug is deep recursion should be turned into a "goto") is a bug. Running out of Perl stack generates a NULL from malloc and then perl processes that NULL and exists. We could have SEH/sig segv handler that conditionally checks for out of C stack condition, traps the signal/exception, and resumes execution with a prompt printing of "out of memory" then exit() so running out of C stack is an identical experience to running out of Perl stack, but I think that is overengineering. Callstack below of the out of C stack crash of the script in the OP.

  ntdll.dll!RtlpLowFragHeapAlloc() + 0x31 bytes
  ntdll.dll!RtlAllocateHeap() + 0x27ef bytes
  msvcr90.dll!malloc(unsigned __int64 size=256) Line 163 + 0x43 bytes C
  perl521.dll!VMem​::Malloc(unsigned __int64 size=31) Line 153 C++
  perl521.dll!Perl_safesysmalloc(unsigned __int64 size=31) Line 147 C
  perl521.dll!Perl_av_extend_guts(interpreter * my_perl=0x0000000001fd1788, av * av=0x000000000000001f, __int64 key=28361912, __int64 * maxp=0x00000000280ca348, sv * * * allocp=0x0000000001fd10f0, sv * * * arrayp=0x0000000001fd1798) Line 174 C
  perl521.dll!Perl_av_extend(interpreter * my_perl=0x0000000000000020, av * av=0x0000000001fcace8, __int64 key=24) Line 81 C
  perl521.dll!Perl_new_stackinfo(interpreter * my_perl=0x0000000001b0c4b8, long stitems=0, long cxitems=29870424) Line 57 C
  perl521.dll!Perl_magic_methcall(interpreter * my_perl=0x0000000000000008, sv * sv=0x0000000001b56c88, const magic * mg=0x0000000001b0c4b8, sv * meth=0x00000000280f5ae1, unsigned long flags=0, unsigned long argc=0, ...) Line 1808 + 0x20 bytes C
  perl521.dll!Perl_magic_nextpack(interpreter * my_perl=0x0000000001baad50, sv * sv=0x0000000001b0c4b8, magic * mg=0x00000000fffffffe, sv * key=0x000000002801ca98) Line 1969 + 0x66 bytes C
  perl521.dll!Perl_hv_iternext_flags(interpreter * my_perl=0x0000000001b0c4b8, hv * hv=0x0000000001ff0628, long flags=28667016) Line 2553 C
  perl521.dll!Perl_do_kv(interpreter * my_perl=0x0000000001b0c4b8) Line 1263 + 0x13 bytes C
  perl521.dll!Perl_runops_standard(interpreter * my_perl=0x0000000000000000) Line 41 + 0x6 bytes C
  perl521.dll!Perl_call_sv(interpreter * my_perl=0x0000000001b0c4b8, sv * sv=0x0000000001ff0630, volatile long flags=4098) Line 2716 C
  perl521.dll!Perl_magic_methcall(interpreter * my_perl=0x0000000000000008, sv * sv=0x0000000001b56c88, const magic * mg=0x0000000001b0c4b8, sv * meth=0x00000000280f5ae1, unsigned long flags=0, unsigned long argc=0, ...) Line 1833 + 0xb bytes C
  perl521.dll!Perl_magic_nextpack(interpreter * my_perl=0x0000000001baad50, sv * sv=0x0000000001b0c4b8, magic * mg=0x00000000fffffffe, sv * key=0x000000002801ca98) Line 1969 + 0x66 bytes C
  perl521.dll!Perl_hv_iternext_flags(interpreter * my_perl=0x0000000001b0c4b8, hv * hv=0x0000000001ff0508, long flags=28667016) Line 2553 C
  perl521.dll!Perl_do_kv(interpreter * my_perl=0x0000000001b0c4b8) Line 1263 + 0x13 bytes C
  perl521.dll!Perl_runops_standard(interpreter * my_perl=0x0000000000000000) Line 41 + 0x6 bytes C
  perl521.dll!Perl_call_sv(interpreter * my_perl=0x0000000001b0c4b8, sv * sv=0x0000000001ff0510, volatile long flags=4098) Line 2716 C
  perl521.dll!Perl_magic_methcall(interpreter * my_perl=0x0000000000000008, sv * sv=0x0000000001b56c88, const magic * mg=0x0000000001b0c4b8, sv * meth=0x00000000280f5ae1, unsigned long flags=0, unsigned long argc=0, ...) Line 1833 + 0xb bytes C
  perl521.dll!Perl_magic_nextpack(interpreter * my_perl=0x0000000001baad50, sv * sv=0x0000000001b0c4b8, magic * mg=0x00000000fffffffe, sv * key=0x000000002801ca98) Line 1969 + 0x66 bytes C
  perl521.dll!Perl_hv_iternext_flags(interpreter * my_perl=0x0000000001b0c4b8, hv * hv=0x0000000001ff03e8, long flags=28667016) Line 2553 C
  perl521.dll!Perl_do_kv(interpreter * my_perl=0x0000000001b0c4b8) Line 1263 + 0x13 bytes C
  perl521.dll!Perl_runops_standard(interpreter * my_perl=0x0000000000000000) Line 41 + 0x6 bytes C
  perl521.dll!Perl_call_sv(interpreter * my_perl=0x0000000001b0c4b8, sv * sv=0x0000000001ff03f0, volatile long flags=4098) Line 2716 C
  perl521.dll!Perl_magic_methcall(interpreter * my_perl=0x0000000000000008, sv * sv=0x0000000001b56c88, const magic * mg=0x0000000001b0c4b8, sv * meth=0x00000000280f5ae1, unsigned long flags=0, unsigned long argc=0, ...) Line 1833 + 0xb bytes C
  perl521.dll!Perl_magic_nextpack(interpreter * my_perl=0x0000000001baad50, sv * sv=0x0000000001b0c4b8, magic * mg=0x00000000fffffffe, sv * key=0x000000002801ca98) Line 1969 + 0x66 bytes C
  perl521.dll!Perl_hv_iternext_flags(interpreter * my_perl=0x0000000001b0c4b8, hv * hv=0x0000000001ff02c8, long flags=28667016) Line 2553 C
  perl521.dll!Perl_do_kv(interpreter * my_perl=0x0000000001b0c4b8) Line 1263 + 0x13 bytes C
  perl521.dll!Perl_runops_standard(interpreter * my_perl=0x0000000000000000) Line 41 + 0x6 bytes C
  perl521.dll!Perl_call_sv(interpreter * my_perl=0x0000000001b0c4b8, sv * sv=0x0000000001ff02d0, volatile long flags=4098) Line 2716 C
  perl521.dll!Perl_magic_methcall(interpreter * my_perl=0x0000000000000008, sv * sv=0x0000000001b56c88, const magic * mg=0x0000000001b0c4b8, sv * meth=0x00000000280f5ae1, unsigned long flags=0, unsigned long argc=0, ...) Line 1833 + 0xb bytes C
  perl521.dll!Perl_magic_nextpack(interpreter * my_perl=0x0000000001baad50, sv * sv=0x0000000001b0c4b8, magic * mg=0x00000000fffffffe, sv * key=0x000000002801ca98) Line 1969 + 0x66 bytes C
  perl521.dll!Perl_hv_iternext_flags(interpreter * my_perl=0x0000000001b0c4b8, hv * hv=0x0000000001ff01a8, long flags=28667016) Line 2553 C
  perl521.dll!Perl_do_kv(interpreter * my_perl=0x0000000001b0c4b8) Line 1263 + 0x13 bytes C
  perl521.dll!Perl_runops_standard(interpreter * my_perl=0x0000000000000000) Line 41 + 0x6 bytes C
  perl521.dll!Perl_call_sv(interpreter * my_perl=0x0000000001b0c4b8, sv * sv=0x0000000001ff01b0, volatile long flags=4098) Line 2716 C
  perl521.dll!Perl_magic_methcall(interpreter * my_perl=0x0000000000000008, sv * sv=0x0000000001b56c88, const magic * mg=0x0000000001b0c4b8, sv * meth=0x00000000280f5ae1, unsigned long flags=0, unsigned long argc=0, ...) Line 1833 + 0xb bytes C
  perl521.dll!Perl_magic_nextpack(interpreter * my_perl=0x0000000001baad50, sv * sv=0x0000000001b0c4b8, magic * mg=0x00000000fffffffe, sv * key=0x000000002801ca98) Line 1969 + 0x66 bytes C
  perl521.dll!Perl_hv_iternext_flags(interpreter * my_perl=0x0000000001b0c4b8, hv * hv=0x0000000001e8a828, long flags=28667016) Line 2553 C
  perl521.dll!Perl_do_kv(interpreter * my_perl=0x0000000001b0c4b8) Line 1263 + 0x13 bytes C
  perl521.dll!Perl_runops_standard(interpreter * my_perl=0x0000000000000000) Line 41 + 0x6 bytes C
  perl521.dll!Perl_call_sv(interpreter * my_perl=0x0000000001b0c4b8, sv * sv=0x0000000001e8a830, volatile long flags=4098) Line 2716 C
  perl521.dll!Perl_magic_methcall(interpreter * my_perl=0x0000000000000008, sv * sv=0x0000000001b56c88, const magic * mg=0x0000000001b0c4b8, sv * meth=0x00000000280f5ae1, unsigned long flags=0, unsigned long argc=0, ...) Line 1833 + 0xb bytes C
  perl521.dll!Perl_magic_nextpack(interpreter * my_perl=0x0000000001baad50, sv * sv=0x0000000001b0c4b8, magic * mg=0x00000000fffffffe, sv * key=0x000000002801ca98) Line 1969 + 0x66 bytes C
  perl521.dll!Perl_hv_iternext_flags(interpreter * my_perl=0x0000000001b0c4b8, hv * hv=0x0000000001e8a708, long flags=28667016) Line 2553 C
  perl521.dll!Perl_do_kv(interpreter * my_perl=0x0000000001b0c4b8) Line 1263 + 0x13 bytes C
  perl521.dll!Perl_runops_standard(interpreter * my_perl=0x0000000000000000) Line 41 + 0x6 bytes C
  perl521.dll!Perl_call_sv(interpreter * my_perl=0x0000000001b0c4b8, sv * sv=0x0000000001e8a710, volatile long flags=4098) Line 2716 C
  perl521.dll!Perl_magic_methcall(interpreter * my_perl=0x0000000000000008, sv * sv=0x0000000001b56c88, const magic * mg=0x0000000001b0c4b8, sv * meth=0x00000000280f5ae1, unsigned long flags=0, unsigned long argc=0, ...) Line 1833 + 0xb bytes C
  perl521.dll!Perl_magic_nextpack(interpreter * my_perl=0x0000000001baad50, sv * sv=0x0000000001b0c4b8, magic * mg=0x00000000fffffffe, sv * key=0x000000002801ca98) Line 1969 + 0x66 bytes C
  perl521.dll!Perl_hv_iternext_flags(interpreter * my_perl=0x0000000001b0c4b8, hv * hv=0x0000000001e8a5e8, long flags=28667016) Line 2553 C
  perl521.dll!Perl_do_kv(interpreter * my_perl=0x0000000001b0c4b8) Line 1263 + 0x13 bytes C
  perl521.dll!Perl_runops_standard(interpreter * my_perl=0x0000000000000000) Line 41 + 0x6 bytes C
  perl521.dll!Perl_call_sv(interpreter * my_perl=0x0000000001b0c4b8, sv * sv=0x0000000001e8a5f0, volatile long flags=4098) Line 2716 C
  perl521.dll!Perl_magic_methcall(interpreter * my_perl=0x0000000000000008, sv * sv=0x0000000001b56c88, const magic * mg=0x0000000001b0c4b8, sv * meth=0x00000000280f5ae1, unsigned long flags=0, unsigned long argc=0, ...) Line 1833 + 0xb bytes C
  perl521.dll!Perl_magic_nextpack(interpreter * my_perl=0x0000000001baad50, sv * sv=0x0000000001b0c4b8, magic * mg=0x00000000fffffffe, sv * key=0x000000002801ca98) Line 1969 + 0x66 bytes C
  perl521.dll!Perl_hv_iternext_flags(interpreter * my_perl=0x0000000001b0c4b8, hv * hv=0x0000000001e8a4c8, long flags=28667016) Line 2553 C
  perl521.dll!Perl_do_kv(interpreter * my_perl=0x0000000001b0c4b8) Line 1263 + 0x13 bytes C
  perl521.dll!Perl_runops_standard(interpreter * my_perl=0x0000000000000000) Line 41 + 0x6 bytes C
  perl521.dll!Perl_call_sv(interpreter * my_perl=0x0000000001b0c4b8, sv * sv=0x0000000001e8a4d0, volatile long flags=4098) Line 2716 C
  perl521.dll!Perl_magic_methcall(interpreter * my_perl=0x0000000000000008, sv * sv=0x0000000001b56c88, const magic * mg=0x0000000001b0c4b8, sv * meth=0x00000000280f5ae1, unsigned long flags=0, unsigned long argc=0, ...) Line 1833 + 0xb bytes C
  perl521.dll!Perl_magic_nextpack(interpreter * my_perl=0x0000000001baad50, sv * sv=0x0000000001b0c4b8, magic * mg=0x00000000fffffffe, sv * key=0x000000002801ca98) Line 1969 + 0x66 bytes C
  perl521.dll!Perl_hv_iternext_flags(interpreter * my_perl=0x0000000001b0c4b8, hv * hv=0x0000000001e8a3a8, long flags=28667016) Line 2553 C
  perl521.dll!Perl_do_kv(interpreter * my_perl=0x0000000001b0c4b8) Line 1263 + 0x13 bytes C
  perl521.dll!Perl_runops_standard(interpreter * my_perl=0x0000000000000000) Line 41 + 0x6 bytes C
  perl521.dll!Perl_call_sv(interpreter * my_perl=0x0000000001b0c4b8, sv * sv=0x0000000001e8a3b0, volatile long flags=4098) Line 2716 C
  perl521.dll!Perl_magic_methcall(interpreter * my_perl=0x0000000000000008, sv * sv=0x0000000001b56c88, const magic * mg=0x0000000001b0c4b8, sv * meth=0x00000000280f5ae1, unsigned long flags=0, unsigned long argc=0, ...) Line 1833 + 0xb bytes C
  perl521.dll!Perl_magic_nextpack(interpreter * my_perl=0x0000000001baad50, sv * sv=0x0000000001b0c4b8, magic * mg=0x00000000fffffffe, sv * key=0x000000002801ca98) Line 1969 + 0x66 bytes C
  perl521.dll!Perl_hv_iternext_flags(interpreter * my_perl=0x0000000001b0c4b8, hv * hv=0x0000000001e8a288, long flags=28667016) Line 2553 C
  perl521.dll!Perl_do_kv(interpreter * my_perl=0x0000000001b0c4b8) Line 1263 + 0x13 bytes C
  perl521.dll!Perl_runops_standard(interpreter * my_perl=0x0000000000000000) Line 41 + 0x6 bytes C
  perl521.dll!Perl_call_sv(interpreter * my_perl=0x0000000001b0c4b8, sv * sv=0x0000000001e8a290, volatile long flags=4098) Line 2716 C
  perl521.dll!Perl_magic_methcall(interpreter * my_perl=0x0000000000000008, sv * sv=0x0000000001b56c88, const magic * mg=0x0000000001b0c4b8, sv * meth=0x00000000280f5ae1, unsigned long flags=0, unsigned long argc=0, ...) Line 1833 + 0xb bytes C
  perl521.dll!Perl_magic_nextpack(interpreter * my_perl=0x0000000001baad50, sv * sv=0x0000000001b0c4b8, magic * mg=0x00000000fffffffe, sv * key=0x000000002801ca98) Line 1969 + 0x66 bytes C
  perl521.dll!Perl_hv_iternext_flags(interpreter * my_perl=0x0000000001b0c4b8, hv * hv=0x0000000001e8a168, long flags=28667016) Line 2553 C
  perl521.dll!Perl_do_kv(interpreter * my_perl=0x0000000001b0c4b8) Line 1263 + 0x13 bytes C
  perl521.dll!Perl_runops_standard(interpreter * my_perl=0x0000000000000000) Line 41 + 0x6 bytes C
.............CUT..................
  perl521.dll!Perl_call_sv(interpreter * my_perl=0x0000000001b0c4b8, sv * sv=0x0000000001f28ae0, volatile long flags=4098) Line 2716 C
  perl521.dll!Perl_magic_methcall(interpreter * my_perl=0x0000000000000008, sv * sv=0x0000000001b56c88, const magic * mg=0x0000000001b0c4b8, sv * meth=0x00000000280f5ae1, unsigned long flags=0, unsigned long argc=0, ...) Line 1833 + 0xb bytes C
  perl521.dll!Perl_magic_nextpack(interpreter * my_perl=0x0000000001baad50, sv * sv=0x0000000001b0c4b8, magic * mg=0x00000000fffffffe, sv * key=0x000000002801ca98) Line 1969 + 0x66 bytes C
  perl521.dll!Perl_hv_iternext_flags(interpreter * my_perl=0x0000000001b0c4b8, hv * hv=0x0000000001f289b8, long flags=28667016) Line 2553 C
  perl521.dll!Perl_do_kv(interpreter * my_perl=0x0000000001b0c4b8) Line 1263 + 0x13 bytes C
  perl521.dll!Perl_runops_standard(interpreter * my_perl=0x0000000000000000) Line 41 + 0x6 bytes C
  perl521.dll!Perl_call_sv(interpreter * my_perl=0x0000000001b0c4b8, sv * sv=0x0000000001f289c0, volatile long flags=4098) Line 2716 C
  perl521.dll!Perl_magic_methcall(interpreter * my_perl=0x0000000000000008, sv * sv=0x0000000001b56c88, const magic * mg=0x0000000001b0c4b8, sv * meth=0x00000000280f5ae1, unsigned long flags=0, unsigned long argc=0, ...) Line 1833 + 0xb bytes C
  perl521.dll!Perl_magic_nextpack(interpreter * my_perl=0x0000000001baad50, sv * sv=0x0000000001b0c4b8, magic * mg=0x00000000fffffffe, sv * key=0x000000002801ca98) Line 1969 + 0x66 bytes C
  perl521.dll!Perl_hv_iternext_flags(interpreter * my_perl=0x0000000001b0c4b8, hv * hv=0x0000000001f28898, long flags=28667016) Line 2553 C
  perl521.dll!Perl_do_kv(interpreter * my_perl=0x0000000001b0c4b8) Line 1263 + 0x13 bytes C
  perl521.dll!Perl_runops_standard(interpreter * my_perl=0x0000000000000000) Line 41 + 0x6 bytes C
  perl521.dll!Perl_call_sv(interpreter * my_perl=0x0000000001b0c4b8, sv * sv=0x0000000001f288a0, volatile long flags=4098) Line 2716 C
  perl521.dll!Perl_magic_methcall(interpreter * my_perl=0x0000000000000008, sv * sv=0x0000000001b56c88, const magic * mg=0x0000000001b0c4b8, sv * meth=0x00000000280f5ae1, unsigned long flags=0, unsigned long argc=0, ...) Line 1833 + 0xb bytes C
  perl521.dll!Perl_magic_nextpack(interpreter * my_perl=0x0000000001baad50, sv * sv=0x0000000001b0c4b8, magic * mg=0x00000000fffffffe, sv * key=0x000000002801ca98) Line 1969 + 0x66 bytes C
  perl521.dll!Perl_hv_iternext_flags(interpreter * my_perl=0x0000000001b0c4b8, hv * hv=0x0000000001f28778, long flags=28667016) Line 2553 C
  perl521.dll!Perl_do_kv(interpreter * my_perl=0x0000000001b0c4b8) Line 1263 + 0x13 bytes C
  perl521.dll!Perl_runops_standard(interpreter * my_perl=0x0000000000000000) Line 41 + 0x6 bytes C
  perl521.dll!Perl_call_sv(interpreter * my_perl=0x0000000001b0c4b8, sv * sv=0x0000000001f28780, volatile long flags=4098) Line 2716 C
  perl521.dll!Perl_magic_methcall(interpreter * my_perl=0x0000000000000008, sv * sv=0x0000000001b56c88, const magic * mg=0x0000000001b0c4b8, sv * meth=0x00000000280f5ae1, unsigned long flags=0, unsigned long argc=0, ...) Line 1833 + 0xb bytes C
  perl521.dll!Perl_magic_nextpack(interpreter * my_perl=0x0000000001baad50, sv * sv=0x0000000001b0c4b8, magic * mg=0x00000000fffffffe, sv * key=0x000000002801ca98) Line 1969 + 0x66 bytes C
  perl521.dll!Perl_hv_iternext_flags(interpreter * my_perl=0x0000000001b0c4b8, hv * hv=0x0000000001f28658, long flags=28667016) Line 2553 C
  perl521.dll!Perl_do_kv(interpreter * my_perl=0x0000000001b0c4b8) Line 1263 + 0x13 bytes C
  perl521.dll!Perl_runops_standard(interpreter * my_perl=0x0000000000000000) Line 41 + 0x6 bytes C
  perl521.dll!Perl_call_sv(interpreter * my_perl=0x0000000001b0c4b8, sv * sv=0x0000000001f28660, volatile long flags=4098) Line 2716 C
  perl521.dll!Perl_magic_methcall(interpreter * my_perl=0x0000000000000008, sv * sv=0x0000000001b56c88, const magic * mg=0x0000000001b0c4b8, sv * meth=0x00000000280f5ae1, unsigned long flags=0, unsigned long argc=0, ...) Line 1833 + 0xb bytes C
  perl521.dll!Perl_magic_nextpack(interpreter * my_perl=0x0000000001baad50, sv * sv=0x0000000001b0c4b8, magic * mg=0x00000000fffffffe, sv * key=0x000000002801ca98) Line 1969 + 0x66 bytes C
  perl521.dll!Perl_hv_iternext_flags(interpreter * my_perl=0x0000000001b0c4b8, hv * hv=0x0000000001f28538, long flags=28667016) Line 2553 C
  perl521.dll!Perl_do_kv(interpreter * my_perl=0x0000000001b0c4b8) Line 1263 + 0x13 bytes C
  perl521.dll!Perl_runops_standard(interpreter * my_perl=0x0000000000000000) Line 41 + 0x6 bytes C
  perl521.dll!Perl_call_sv(interpreter * my_perl=0x0000000001b0c4b8, sv * sv=0x0000000001f28540, volatile long flags=4098) Line 2716 C
  perl521.dll!Perl_magic_methcall(interpreter * my_perl=0x0000000000000008, sv * sv=0x0000000001b56c88, const magic * mg=0x0000000001b0c4b8, sv * meth=0x00000000280f5ae1, unsigned long flags=0, unsigned long argc=0, ...) Line 1833 + 0xb bytes C
  perl521.dll!Perl_magic_nextpack(interpreter * my_perl=0x0000000001baad50, sv * sv=0x0000000001b0c4b8, magic * mg=0x00000000fffffffe, sv * key=0x000000002801ca98) Line 1969 + 0x66 bytes C
  perl521.dll!Perl_hv_iternext_flags(interpreter * my_perl=0x0000000001b0c4b8, hv * hv=0x0000000001f28418, long flags=28667016) Line 2553 C
  perl521.dll!Perl_do_kv(interpreter * my_perl=0x0000000001b0c4b8) Line 1263 + 0x13 bytes C
  perl521.dll!Perl_runops_standard(interpreter * my_perl=0x0000000000000000) Line 41 + 0x6 bytes C
  perl521.dll!Perl_call_sv(interpreter * my_perl=0x0000000001b0c4b8, sv * sv=0x0000000001f28420, volatile long flags=4098) Line 2716 C
  perl521.dll!Perl_magic_methcall(interpreter * my_perl=0x0000000000000008, sv * sv=0x0000000001b56c88, const magic * mg=0x0000000001b0c4b8, sv * meth=0x00000000280f5ae1, unsigned long flags=0, unsigned long argc=0, ...) Line 1833 + 0xb bytes C
  perl521.dll!Perl_magic_nextpack(interpreter * my_perl=0x0000000001baad50, sv * sv=0x0000000001b0c4b8, magic * mg=0x00000000fffffffe, sv * key=0x000000002801ca98) Line 1969 + 0x66 bytes C
***Visual C debugger refuses to show any more frames***********

--
bulk88 ~ bulk88 at hotmail.com

From @bulk88

out_of_c_stack.PNG

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

From @shlomif

On Tue Mar 17 15​:50​:59 2015, shay wrote​:

The following program (put together by Matthew Horsfall (alh)
<wolfsage@​gmail.com> in the course of investigating
rt.perl.org#124048) SEGVs after hitting deep recursion in the tied
hash FIRSTKEY subroutine​:

#!/usr/bin/perl

use strict;
use warnings;

{
package Tied​::Thingy;
require Tie​::Hash;

our @​ISA = qw(Tie​::StdHash);

sub FIRSTKEY {
my $self = shift;
return keys %{ $self->{parent} };
}
}

my %x;
tie %x, 'Tied​::Thingy';
$x{parent} = \%x;

for my $k (keys %x) {
print "K​: $k\n";
}

The original bug report was ultimately a case of garbage-in, garbage-
out, but I'm logging the SEGV here on the basis that any crash in perl
is surely a bug.

This program causes a segmentation fault for the system perl here on Mageia Linux 5 x86-64​:

«
shlomif@​telaviv1​:~$ which perl
/usr/bin/perl
shlomif@​telaviv1​:~$ rpm -q perl
perl-5.20.1-8.mga5
shlomif@​telaviv1​:~$ perl Test1.pl
Deep recursion on subroutine "Tied​::Thingy​::FIRSTKEY" at Test1.pl line 14.
Segmentation fault
shlomif@​telaviv1​:~$
»

It also segfaults bleadperl on the same system​:

«
shlomif@​telaviv1​:~/Download/unpack/perl/p5/git/perl$ ./perl -Ilib ~/Test1.pl
Deep recursion on subroutine "Tied​::Thingy​::FIRSTKEY" at /home/shlomif/Test1.pl line 14.
Segmentation fault
shlomif@​telaviv1​:~/Download/unpack/perl/p5/git/perl$
»

-- Shlomi Fish