# New Ticket Created by Dan Collins
# Please include the string: [perl #128261]
# in the subject line of all future correspondence about this issue.
# <URL: https://rt.perl.org/Ticket/Display.html?id=128261 >

Greetings Porters,

I have compiled bleadperl with the afl-gcc compiler using:

./Configure -Dusedevel -Dprefix='/usr/local/perl-afl' -Dcc='ccache afl-gcc' -Uuselongdouble -Duse64bitall -Doptimize=-g -Uversiononly -Uman1dir -Uman3dir -Dusequadmath -des
AFL_HARDEN=1 make && make test

And then fuzzed the resulting binary using:

AFL_NO_VAR_CHECK=1 afl-fuzz -i in -o out bin/perl @@

After reducing testcases using `afl-tmin` and performing additional minimization by hand, I have located the following testcase that triggers an assert fail in debug buids of the perl interpreter. The testcase is the file below. On normal builds, this runs normally (albeit with an expected warning). On debug builds, this returns an assert fail.

dcollins@nightshade64:~/perldebug$ ./perl -Ilib -e 'sub MODIFY_HASH_ATTRIBUTES{}my(%o):s==0'
perl: sv.c:2595: Perl_sv_2nv_flags: Assertion `((svtype)((sv)->sv_flags & 0xff)) != SVt_PVAV && ((svtype)((sv)->sv_flags & 0xff)) != SVt_PVHV && ((svtype)((sv)->sv_flags & 0xff)) != SVt_PVFM' failed.

This seems to be the "hash equivalent" of [perl #128183]?

Debugging tool output is below. A git bisect was performed and reported the following, which is the commit where the assert was initially added.

217f6fa330a187be32a68556507e3165b8747f55 is the first bad commit
commit 217f6fa330a187be32a68556507e3165b8747f55
Author: Father Chrysostomos <sprout@cpan.org>
Date: Fri Jul 19 08:51:47 2013 -0700

     sv.c: Assert that sv_[ivp]v are not passed aggregates

     The lack of assertions can hide bugs. See 32a609747bffb for instance

:100644 100644 3ac0a2bce83bc12406be1fa22acefa8f8a2014c7 daa87f00081d96c8d15f94f02c32cd85e8af0266 M sv.c
bisect run success


dcollins@nightshade64:~/perldebug$ gdb --args ./perl -Ilib -e 'sub MODIFY_HASH_ATTRIBUTES{}my(%o):s==0'
GNU gdb (GDB) 7.10
Copyright (C) 2015 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-unknown-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
Find the GDB manual and other documentation resources online at:
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from ./perl...done.
(gdb) run
Starting program: /home/dcollins/perldebug/perl -Ilib -e sub\ MODIFY_HASH_ATTRIBUTES\{\}my\(%o\):s==0
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
perl: sv.c:2595: Perl_sv_2nv_flags: Assertion `((svtype)((sv)->sv_flags & 0xff)) != SVt_PVAV && ((svtype)((sv)->sv_flags & 0xff)) != SVt_PVHV && ((svtype)((sv)->sv_flags & 0xff)) != SVt_PVFM' failed.

Program received signal SIGABRT, Aborted.
0x00007ffff6cf9478 in raise () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) bt
#0 0x00007ffff6cf9478 in raise () from /lib/x86_64-linux-gnu/libc.so.6
#1 0x00007ffff6cfa8fa in abort () from /lib/x86_64-linux-gnu/libc.so.6
#2 0x00007ffff6cf23a7 in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#3 0x00007ffff6cf2452 in __assert_fail () from /lib/x86_64-linux-gnu/libc.so.6
#4 0x00000000005cd9fc in Perl_sv_2nv_flags (sv=0xab2730, flags=0) at sv.c:2594
#5 0x000000000062c724 in Perl_do_ncmp (left=0xab2730, right=0xab27a8) at pp.c:2281
#6 0x00000000005a933d in Perl_pp_eq () at pp_hot.c:464
#7 0x000000000055a245 in Perl_runops_debug () at dump.c:2239
#8 0x00000000004623d3 in S_run_body (oldscope=1) at perl.c:2517
#9 0x00000000004619fe in perl_run (my_perl=0xa9c010) at perl.c:2440
#10 0x000000000041eae0 in main (argc=4, argv=0x7fffffffe608, env=0x7fffffffe630)
     at perlmain.c:116
(gdb) f 4
#4 0x00000000005cd9fc in Perl_sv_2nv_flags (sv=0xab2730, flags=0) at sv.c:2594
2594 assert (SvTYPE(sv) != SVt_PVAV && SvTYPE(sv) != SVt_PVHV
(gdb) l
2589 NV
2590 Perl_sv_2nv_flags(pTHX_ SV *const sv, const I32 flags)
2591 {
2594 assert (SvTYPE(sv) != SVt_PVAV && SvTYPE(sv) != SVt_PVHV
2595 && SvTYPE(sv) != SVt_PVFM);
2596 if (SvGMAGICAL(sv) || SvVALID(sv) || isREGEXP(sv)) {
2597 /* FBMs use the space for SvIVX and SvNVX for other purposes, and use
2598 the same flag bit as SVf_IVisUV, so must not let them cache NVs.
(gdb) info locals
__PRETTY_FUNCTION__ = "Perl_sv_2nv_flags"
(gdb) q


No reported memory management errors.

**PERL -V**

dcollins@nightshade64:~/perldebug$ ./perl -Ilib -V
Summary of my perl5 (revision 5 version 25 subversion 2) configuration:
   Commit id: c29dfc6a6c45f86648c51f961304254cc3c449b9
     osname=linux, osvers=4.5.0-2-amd64, archname=x86_64-linux-ld
     uname='linux nightshade64 4.5.0-2-amd64 #1 smp debian 4.5.3-2 (2016-05-08) x86_64 gnulinux '
     config_args='-Dusedevel -Dprefix=/usr/local/perl-afl -Dcc=ccache gcc-6.1 -Duselongdouble -Duse64bitall -Doptimize=-g -Uversiononly -Uman1dir -Uman3dir -DDEBUGGING -DPERL_POISON -des'
     hint=recommended, useposix=true, d_sigaction=define
     useithreads=undef, usemultiplicity=undef
     use64bitint=define, use64bitall=define, uselongdouble=define
     usemymalloc=n, bincompat5005=undef
     cc='ccache gcc-6.1', ccflags ='-fwrapv -DDEBUGGING -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
     cppflags='-fwrapv -DDEBUGGING -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include'
     ccversion='', gccversion='6.1.0', gccosandvers=''
     intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678, doublekind=3
     d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16, longdblkind=3
     ivtype='long', ivsize=8, nvtype='long double', nvsize=16, Off_t='off_t', lseeksize=8
     alignbytes=16, prototype=define
   Linker and Libraries:
     ld='ccache gcc-6.1', ldflags =' -fstack-protector-strong -L/usr/local/lib'
     libpth=/usr/local/lib /usr/local/lib/gcc/x86_64-pc-linux-gnu/6.1.0/include-fixed /usr/include/x86_64-linux-gnu /usr/lib /lib/x86_64-linux-gnu /lib/../lib /usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib
     libs=-lpthread -lnsl -ldl -lm -lcrypt -lutil -lc
     perllibs=-lpthread -lnsl -ldl -lm -lcrypt -lutil -lc
     libc=libc-2.22.so, so=so, useshrplib=false, libperl=libperl.a
   Dynamic Linking:
     dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
     cccdlflags='-fPIC', lddlflags='-shared -g -L/usr/local/lib -fstack-protector-strong'

Characteristics of this binary (from libperl):
                         USE_64_BIT_ALL USE_64_BIT_INT USE_LARGE_FILES
                         USE_PERLIO USE_PERL_ATOF
   Built under linux
   Compiled at May 26 2016 17:57:37

Search Discussions

Discussion Posts

Follow ups

Related Discussions

Discussion Navigation
viewthread | post
posts ‹ prev | 1 of 2 | next ›
Discussion Overview
groupperl5-porters @
postedMay 27, '16 at 1:57a
activeMay 27, '16 at 2:49a

1 user in discussion

Father Chrysostomos via RT: 2 posts



site design / logo © 2017 Grokbase