develooper Front page | perl.perl5.porters | Postings from October 2015

[perl #126482] Assert fail w/o other symptoms - op.c:7750Perl_cv_const_sv_or_av

Dan Collins
October 29, 2015 02:59
[perl #126482] Assert fail w/o other symptoms - op.c:7750Perl_cv_const_sv_or_av
Message ID:
# New Ticket Created by  Dan Collins 
# Please include the string:  [perl #126482]
# in the subject line of all future correspondence about this issue. 
# <URL: >

Greetings Porters,

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

./Configure -Dusedevel -Dprefix='/usr/local/perl-afl' -Dcc='ccache afl-gcc' -Duselongdouble -Duse64bitall -Doptimize=-g -Uversiononly -Uman1dir -Uman3dir -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 DEBUGGING perls without any other symptoms in the normal perl interpreter. The testcase is the file:

sub(){sub ub(){0}ub ub

This is indeed a rather odd thing to do, as it couldn't conceivably be expected to do anything but error, but since normal perls error properly, I suspect that this assert fail could be a sign that a more complex program could cause a more complex error state even in normal perls, or that normal perls could break down the line. 

dcollins@nightshade64:/usr/local/perl-afl$ ./bin/perl -e 'sub(){sub ub(){0}ub ub'
perl: op.c:7750: Perl_cv_const_sv_or_av: Assertion `((svtype)((cv)->sv_flags & 0xff)) == SVt_PVCV || ((svtype)((cv)->sv_flags & 0xff)) == SVt_PVFM' failed.

The output with a normal perl is the expected error:

dcollins@nightshade64:/usr/local/perl-afl$ ~/perl/perl -e 'sub(){sub ub(){0}ub ub'
Too many arguments for main::ub at -e line 1, at EOF
Missing right curly or square bracket at -e line 1, at end of line
syntax error at -e line 1, at EOF
Execution of -e aborted due to compilation errors.


(gdb) run
Starting program: /usr/local/perl-afl/bin/perl -e sub\(\)\{sub\ ub\(\)\{0\}ub\ ub
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/".
perl: op.c:7750: Perl_cv_const_sv_or_av: Assertion `((svtype)((cv)->sv_flags & 0xff)) == SVt_PVCV || ((svtype)((cv)->sv_flags & 0xff)) == SVt_PVFM' failed.

Program received signal SIGABRT, Aborted.
0x00007ffff6cf4107 in raise () from /lib/x86_64-linux-gnu/
(gdb) bt
#0  0x00007ffff6cf4107 in raise () from /lib/x86_64-linux-gnu/
#1  0x00007ffff6cf54e8 in abort () from /lib/x86_64-linux-gnu/
#2  0x00007ffff6ced226 in ?? () from /lib/x86_64-linux-gnu/
#3  0x00007ffff6ced2d2 in __assert_fail ()
   from /lib/x86_64-linux-gnu/
#4  0x0000000000441119 in Perl_cv_const_sv_or_av (cv=cv@entry=0x11ba930)
    at op.c:7750
#5  0x00000000005ebb24 in Perl_yylex () at toke.c:7045
#6  0x00000000006527ad in Perl_yyparse (gramtype=gramtype@entry=258)
    at perly.c:322
#7  0x000000000051e645 in S_parse_body (env=env@entry=0x0,
    xsinit=xsinit@entry=0x428c60 <xs_init>) at perl.c:2307
#8  0x0000000000525437 in perl_parse (my_perl=<optimized out>,
    xsinit=xsinit@entry=0x428c60 <xs_init>, argc=<optimized out>,
    argv=<optimized out>, env=env@entry=0x0) at perl.c:1634
#9  0x0000000000428888 in main (argc=3, argv=0x7fffffffe658,
    env=0x7fffffffe678) at perlmain.c:114
(gdb) f 4
#4  0x0000000000441119 in Perl_cv_const_sv_or_av (cv=cv@entry=0x11ba930)
    at op.c:7750
7750        assert (SvTYPE(cv) == SVt_PVCV || SvTYPE(cv) == SVt_PVFM);
(gdb) info locals
__PRETTY_FUNCTION__ = "Perl_cv_const_sv_or_av"
(gdb) q


dcollins@nightshade64:/usr/local/perl-afl$ valgrind ./bin/perl -e 'sub(){sub ub(){0}ub ub'
==23798== Memcheck, a memory error detector
==23798== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==23798== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==23798== Command: ./bin/perl -e sub(){sub\ ub(){0}ub\ ub
perl: op.c:7750: Perl_cv_const_sv_or_av: Assertion `((svtype)((cv)->sv_flags & 0xff)) == SVt_PVCV || ((svtype)((cv)->sv_flags & 0xff)) == SVt_PVFM' failed.
==23798== Process terminating with default action of signal 6 (SIGABRT)
==23798==    at 0x5BDC107: raise (raise.c:56)
==23798==    by 0x5BDD4E7: abort (abort.c:89)
==23798==    by 0x5BD5225: __assert_fail_base (assert.c:92)
==23798==    by 0x5BD52D1: __assert_fail (assert.c:101)
==23798==    by 0x441118: Perl_cv_const_sv_or_av (op.c:7750)
==23798==    by 0x5EBB23: Perl_yylex (toke.c:7045)
==23798==    by 0x6527AC: Perl_yyparse (perly.c:322)
==23798==    by 0x51E644: S_parse_body (perl.c:2307)
==23798==    by 0x525436: perl_parse (perl.c:1634)
==23798==    by 0x428887: main (perlmain.c:114)
==23798== HEAP SUMMARY:
==23798==     in use at exit: 118,114 bytes in 563 blocks
==23798==   total heap usage: 697 allocs, 134 frees, 136,150 bytes allocated
==23798== LEAK SUMMARY:
==23798==    definitely lost: 176 bytes in 1 blocks
==23798==    indirectly lost: 1,974 bytes in 20 blocks
==23798==      possibly lost: 24 bytes in 1 blocks
==23798==    still reachable: 115,940 bytes in 541 blocks
==23798==         suppressed: 0 bytes in 0 blocks
==23798== Rerun with --leak-check=full to see details of leaked memory
==23798== For counts of detected and suppressed errors, rerun with: -v
==23798== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

**PERL -V**

dcollins@nightshade64:/usr/local/perl-afl$ ./bin/perl -V
Summary of my perl5 (revision 5 version 23 subversion 5) configuration:
  Commit id: 7195e5da55a40d15e29ad80562668bdd6895441f
    osname=linux, osvers=3.16.0-4-amd64, archname=x86_64-linux-ld
    uname='linux nightshade64 3.16.0-4-amd64 #1 smp debian 3.16.7-ckt11-1+deb8u4 (2015-09-19) x86_64 gnulinux '
    config_args='-Dusedevel -Dprefix=/usr/local/perl-afl -Dcc=ccache afl-gcc -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 afl-gcc', 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='5.2.0', 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 afl-gcc', ldflags =' -fstack-protector-strong -L/usr/local/lib'
    libpth=/usr/local/lib /usr/local/lib/gcc/x86_64-unknown-linux-gnu/5.2.0/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, 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_INT USE_LARGE_FILES USE_LOCALE
                        USE_PERLIO USE_PERL_ATOF
  Built under linux
  Compiled at Oct 22 2015 15:44:40
    . Perl Programming lists via nntp and http.
Comments to Ask Bjørn Hansen at | Group listing | About