From @bulk88

Created by @bulk88

Perl lexer (???) has a deep recursion bug in Perl_scalarvoid when given a very large Perl subroutine to run. Perl_scalarvoid calls itself over and over, for what I blindly guess is every opcode in the sub. If there are too many opcodes, C stack overflows.

I could not replicate this with any stock ActivePerl (AP 5.10.0, AP 5.12.3). While the test script is running, ActivePerls peak at 8 MB on the C stack. I checked with VMMAP. If I lower the stack reserve from 16 MB to 256KB in the PE header on perl.exe from ActivePerls, I will get the same exact Perl_scalarvoid stack overflow. There is no reason for the interpreter to peak at many MBs of C stack, which is irreversibly expanded (there are OS specific ways to shrink C stacks.... I know it can be done with VirtualFree and VirtualAlloc on Windows, but that is the wrong way to fix C stack recursion) and wasted, never to be used again after BEGIN blocks run. I have not tested doing the "require" at runtime. On other perl scripts and apps I run, all the interpreter (APs and my compiled Perl) peak at 20-50KB of C stack which is fine. I assume that the reason that my self-compiled Perl will stack overflow at 16MB and ActivePerls do not is because of high C stack overhead of each recursive Perl_scalarvoid when Perl is compiled with -Od (no registers) meanwhile ActivePerls are compiled with -O1 (small code).

I wrote this test script to test how efficient Perl is at returning memory to the OS after a Perl Module is "use"d and if, and how well, memory behind the BEGIN blocks (SVs, CVs, Opcodes, pads, raw malloced blocks) is returned to the OS. If I lower the 100000 to 50000 in the test script, the script will run without a stack overflow. On sucessful runs, malloced memory went down from ~60MB inside the module BEGIN block (at "print "after branches\n";") to ~3MB at runtime ("print "in main\n";" ) according to VMMAP (private/yellow memory). C Stack remained at many MBs (7 to 8MB at 50000 in test script).

Perl_scalarvoid, whatever it does to opcodes, should run in a loop down the optree, not recursively on every opcode and thus eating away the C stack. I request that the above-reported bug be fixed.

Perl Info


Flags:
    category=core
    severity=high

Site configuration information for perl 5.12.2:

Configured by Owner at Wed Mar 23 08:05:23 2011.

Summary of my perl5 (revision 5 version 12 subversion 2) configuration:
   
  Platform:
    osname=MSWin32, osvers=5.1, archname=MSWin32-x86-multi-thread
    uname=''
    config_args='undef'
    hint=recommended, useposix=true, d_sigaction=undef
    useithreads=define, usemultiplicity=define
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=undef, use64bitall=undef, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cl', ccflags ='-nologo -GF -W3 -Od -MD -Zi -DDEBUGGING -DWIN32 -D_CONSOLE -DNO_STRICT -DHAVE_DES_FCRYPT  -DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS -DUSE_PERLIO',
    optimize='-Od -MD -Zi -DDEBUGGING',
    cppflags='-DWIN32'
    ccversion='13.10.3077', gccversion='', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
    d_longlong=undef, longlongsize=8, d_longdbl=define, longdblsize=8
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='__int64', lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='link', ldflags ='-nologo -nodefaultlib -debug  -libpath:"c:\perl512\lib\CORE"  -machine:x86'
    libpth="c:\Program Files\Microsoft Visual Studio .NET 2003\VC7\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 ws2_32.lib mpr.lib winmm.lib  version.lib odbc32.lib odbccp32.lib comctl32.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 ws2_32.lib mpr.lib winmm.lib  version.lib odbc32.lib odbccp32.lib comctl32.lib msvcrt.lib
    libc=msvcrt.lib, so=dll, useshrplib=true, libperl=perl512.lib
    gnulibc_version=''
  Dynamic Linking:
    dlsrc=dl_win32.xs, dlext=dll, d_dlsymun=undef, ccdlflags=' '
    cccdlflags=' ', lddlflags='-dll -nologo -nodefaultlib -debug  -libpath:"c:\perl512\lib\CORE"  -machine:x86'

Locally applied patches:
    


@INC for perl 5.12.2:
    C:/perl512/site/lib
    C:/perl512/lib
    .


Environment for perl 5.12.2:
    HOME (unset)
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=C:\Program Files\Microsoft Visual Studio .NET 2003\Common7\IDE;C:\Program Files\Microsoft Visual Studio .NET 2003\VC7\BIN;C:\Program Files\Microsoft Visual Studio .NET 2003\Common7\Tools;C:\Program Files\Microsoft Visual Studio .NET 2003\Common7\Tools\bin\prerelease;C:\Program Files\Microsoft Visual Studio .NET 2003\Common7\Tools\bin;C:\Program Files\Microsoft Visual Studio .NET 2003\SDK\v1.1\bin;C:\WINDOWS\Microsoft.NET\Framework\v1.1.4322;C:\perl512\bin;C:\sources\glibbin\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\system32\wbem;C:\Perl\site\bin;C:\Perl\bin;C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\bin;C:\cygwin\bin;
    PERL_BADLANG (unset)
    PERL_DEBUG_MSTATS=2
    SHELL (unset)

C stack overflow in Perl_scalarvoid #11866

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