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[perl #126481] Assert fail w/o other symptoms - regcomp.c:13901S_handle_regex_sets with a regex that seems sort of valid

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From:
Dan Collins
Date:
October 29, 2015 02:59
Subject:
[perl #126481] Assert fail w/o other symptoms - regcomp.c:13901S_handle_regex_sets with a regex that seems sort of valid
Message ID:
rt-4.0.18-17854-1446087546-758.126481-75-0@perl.org
# New Ticket Created by  Dan Collins 
# Please include the string:  [perl #126481]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=126481 >


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:

0=/(?[!!(\w])/

dcollins@nightshade64:/usr/local/perl-afl$ ./bin/perl -e '0=/(?[!!(\w])/'
The regex_sets feature is experimental in regex; marked by <-- HERE in m/(?[ <-- HERE !!(\w])/ at -e line 1.
perl: regcomp.c:13901: S_handle_regex_sets: Assertion `(! ((lhs)->sv_flags & 0x00000100))' failed.
Aborted

The output with a normal perl is the expected error:

dcollins@nightshade64:/usr/local/perl-afl$ ~/perl/perl -e '0=/(?[!!(\w])/'
The regex_sets feature is experimental in regex; marked by <-- HERE in m/(?[ <-- HERE !!(\w])/ at -e line 1.
Unmatched ( in regex; marked by <-- HERE in m/(?[!!(\w <-- HERE ])/ at -e line 1.


**GDB**

(gdb) run
Starting program: /usr/local/perl-afl/bin/perl -e 0=/\(\?\[\!\!\(\\w\]\)/
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
The regex_sets feature is experimental in regex; marked by <-- HERE in m/(?[ <-- HERE !!(\w])/ at -e line 1.
perl: regcomp.c:13901: S_handle_regex_sets: Assertion `(! ((lhs)->sv_flags & 0x00000100))' failed.

Program received signal SIGABRT, Aborted.
0x00007ffff6cf4107 in raise () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) bt
#0  0x00007ffff6cf4107 in raise () from /lib/x86_64-linux-gnu/libc.so.6
#1  0x00007ffff6cf54e8 in abort () from /lib/x86_64-linux-gnu/libc.so.6
#2  0x00007ffff6ced226 in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#3  0x00007ffff6ced2d2 in __assert_fail ()
   from /lib/x86_64-linux-gnu/libc.so.6
#4  0x000000000070ace9 in S_handle_regex_sets (
    pRExC_state=pRExC_state@entry=0x7fffffffddd0,
    return_invlist=return_invlist@entry=0x0,
    flagp=flagp@entry=0x7fffffffd98c, depth=depth@entry=5,
    oregcomp_parse=oregcomp_parse@entry=0x11c3b41 "?[!!(\\w])")
    at regcomp.c:13901
#5  0x00000000006e23ea in S_reg (pRExC_state=0x7fffffffddd0, paren=91,
    flagp=0x7fffffffd98c, depth=5) at regcomp.c:10492
#6  0x000000000070c37d in S_regatom (
    pRExC_state=pRExC_state@entry=0x7fffffffddd0,
    flagp=flagp@entry=0x7fffffffdb0c, depth=depth@entry=4) at regcomp.c:11800
#7  0x0000000000718d39 in S_regpiece (depth=3, flagp=<synthetic pointer>,
    pRExC_state=0x7fffffffddd0) at regcomp.c:10878
#8  S_regbranch (pRExC_state=pRExC_state@entry=0x7fffffffddd0,
    flagp=flagp@entry=0x7fffffffdbbc, first=first@entry=1,
    depth=depth@entry=2) at regcomp.c:10803
#9  0x0000000000738b03 in S_reg (
    pRExC_state=pRExC_state@entry=0x7fffffffddd0,
---Type <return> to continue, or q <return> to quit---
    flagp=flagp@entry=0x7fffffffdc9c, depth=1, paren=0) at regcomp.c:10548
#10 0x00000000007772eb in Perl_re_op_compile (patternp=patternp@entry=0x0,
    pat_count=<optimized out>, pat_count@entry=0, expr=<optimized out>,
    expr@entry=0x11c3918, eng=0xef8d40 <PL_core_reg_engine>,
    old_re=old_re@entry=0x0, is_bare_re=is_bare_re@entry=0x0,
    orig_rx_flags=0, pm_flags=0) at regcomp.c:6953
#11 0x00000000004d3fca in Perl_pmruntime (o=0x11c3958, expr=0x11c3918,
    repl=<optimized out>, isreg=isreg@entry=true, floor=<optimized out>)
    at op.c:5580
#12 0x00000000006550f5 in Perl_yyparse (gramtype=gramtype@entry=258)
    at perly.y:1032
#13 0x000000000051e645 in S_parse_body (env=env@entry=0x0,
    xsinit=xsinit@entry=0x428c60 <xs_init>) at perl.c:2307
#14 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
#15 0x0000000000428888 in main (argc=3, argv=0x7fffffffe658,
    env=0x7fffffffe678) at perlmain.c:114
(gdb) f 4
#4  0x000000000070ace9 in S_handle_regex_sets (
    pRExC_state=pRExC_state@entry=0x7fffffffddd0,
    return_invlist=return_invlist@entry=0x0,
    flagp=flagp@entry=0x7fffffffd98c, depth=depth@entry=5,
    oregcomp_parse=oregcomp_parse@entry=0x11c3b41 "?[!!(\\w])")
    at regcomp.c:13901
13901                   assert(IS_OPERAND(lhs));
(gdb) info locals
stacked_operator = 33 '!'
lhs = <optimized out>
rhs = 0x11ba9d8
stacked_ptr = <optimized out>
fence_ptr = <optimized out>
top_index = <optimized out>
top_ptr = <optimized out>
current = 0x0
only_to_avoid_leaks = <optimized out>
curchar = 93 ']'
start = 18590168
end = 0
final = 0x0
result_string = <optimized out>
fence_stack = 0x11ba948
fence = 2
len = 0
node = <optimized out>
save_fold = false
save_end = <optimized out>
save_parse = <optimized out>
in_locale = false
re_debug_flags = 0
---Type <return> to continue, or q <return> to quit---
__PRETTY_FUNCTION__ = "S_handle_regex_sets"
(gdb) q


**VALGRIND**

dcollins@nightshade64:/usr/local/perl-afl$ valgrind ./bin/perl -e '0=/(?[!!(\w])/'
==44884== Memcheck, a memory error detector
==44884== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==44884== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==44884== Command: ./bin/perl -e 0=/(?[!!(\\w])/
==44884==
The regex_sets feature is experimental in regex; marked by <-- HERE in m/(?[ <-- HERE !!(\w])/ at -e line 1.
perl: regcomp.c:13901: S_handle_regex_sets: Assertion `(! ((lhs)->sv_flags & 0x00000100))' failed.
==44884==
==44884== Process terminating with default action of signal 6 (SIGABRT)
==44884==    at 0x5BDC107: raise (raise.c:56)
==44884==    by 0x5BDD4E7: abort (abort.c:89)
==44884==    by 0x5BD5225: __assert_fail_base (assert.c:92)
==44884==    by 0x5BD52D1: __assert_fail (assert.c:101)
==44884==    by 0x70ACE8: S_handle_regex_sets (regcomp.c:13901)
==44884==    by 0x6E23E9: S_reg (regcomp.c:10492)
==44884==    by 0x70C37C: S_regatom (regcomp.c:11800)
==44884==    by 0x718D38: S_regpiece (regcomp.c:10878)
==44884==    by 0x718D38: S_regbranch (regcomp.c:10803)
==44884==    by 0x738B02: S_reg.constprop.46 (regcomp.c:10548)
==44884==    by 0x7772EA: Perl_re_op_compile (regcomp.c:6953)
==44884==    by 0x4D3FC9: Perl_pmruntime (op.c:5580)
==44884==    by 0x6550F4: Perl_yyparse (perly.y:1032)
==44884==
==44884== HEAP SUMMARY:
==44884==     in use at exit: 139,830 bytes in 561 blocks
==44884==   total heap usage: 688 allocs, 127 frees, 165,712 bytes allocated
==44884==
==44884== LEAK SUMMARY:
==44884==    definitely lost: 176 bytes in 1 blocks
==44884==    indirectly lost: 1,974 bytes in 20 blocks
==44884==      possibly lost: 16 bytes in 1 blocks
==44884==    still reachable: 137,664 bytes in 539 blocks
==44884==         suppressed: 0 bytes in 0 blocks
==44884== Rerun with --leak-check=full to see details of leaked memory
==44884==
==44884== For counts of detected and suppressed errors, rerun with: -v
==44884== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
Aborted


**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
  Platform:
    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
  Compiler:
    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',
    optimize='-g',
    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
    libc=libc-2.19.so, so=so, useshrplib=false, libperl=libperl.a
    gnulibc_version='2.19'
  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):
  Compile-time options: DEBUGGING HAS_TIMES PERLIO_LAYERS PERL_COPY_ON_WRITE
                        PERL_DONT_CREATE_GVSV
                        PERL_HASH_FUNC_ONE_AT_A_TIME_HARD PERL_MALLOC_WRAP
                        PERL_PRESERVE_IVUV PERL_USE_DEVEL USE_64_BIT_ALL
                        USE_64_BIT_INT USE_LARGE_FILES USE_LOCALE
                        USE_LOCALE_COLLATE USE_LOCALE_CTYPE
                        USE_LOCALE_NUMERIC USE_LOCALE_TIME USE_LONG_DOUBLE
                        USE_PERLIO USE_PERL_ATOF
  Built under linux
  Compiled at Oct 22 2015 15:44:40
  @INC:
    /usr/local/perl-afl/lib/site_perl/5.23.5/x86_64-linux-ld
    /usr/local/perl-afl/lib/site_perl/5.23.5
    /usr/local/perl-afl/lib/5.23.5/x86_64-linux-ld
    /usr/local/perl-afl/lib/5.23.5
    /usr/local/perl-afl/lib/site_perl/5.23.4
    /usr/local/perl-afl/lib/site_perl
    .


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