[perl #130632] Memory leak in Perl_yylex (toke.c:7027)

# New Ticket Created by  Sergey Aleynikov 
# Please include the string:  [perl #130632]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=130632 >


This is a bug report for perl from sergey.aleynikov@gmail.com,
generated with the help of perlbug 1.40 running under perl 5.25.9.


-----------------------------------------------------------------
[Please describe your issue here]

While fuzzing perl v5.25.8-216-gfbceb79751 built with afl and run
under libdislocator, I found the following program

s//'x' ^ -"s:\347"/eeg

to cause a memory leak report under ASAN:

=================================================================
==27209==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 4 byte(s) in 1 object(s) allocated from:
    #0 0x4ea6c8 in malloc (/home/afl/afl-asan/perl+0x4ea6c8)
    #1 0x8504be in Perl_safesysmalloc /home/afl/afl-asan/util.c:153:21
    #2 0x8564ab in Perl_savepvn /home/afl/afl-asan/util.c:1177:5
    #3 0x675843 in Perl_yylex /home/afl/afl-asan/toke.c:7027:23
    #4 0x6f6072 in Perl_yyparse /home/afl/afl-asan/perly.c:340:34
    #5 0xb0c78f in S_doeval_compile /home/afl/afl-asan/pp_ctl.c:3432:77
    #6 0xb09a17 in Perl_pp_entereval /home/afl/afl-asan/pp_ctl.c:4292:9
    #7 0x84b114 in Perl_runops_debug /home/afl/afl-asan/dump.c:2406:23
    #8 0x5f1b05 in S_run_body /home/afl/afl-asan/perl.c:2528:2
    #9 0x5f1b05 in perl_run /home/afl/afl-asan/perl.c:2451
    #10 0x5224d2 in main /home/afl/afl-asan/perlmain.c:123:9
    #11 0x7efca17d02b0 in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x202b0)

SUMMARY: AddressSanitizer: 4 byte(s) leaked in 1 allocation(s).

Leaked scalar comes from the following line

pl_yylval.pval = savepvn(PL_tokenbuf, len+1);

In this case PL_tokenbuf is "Us" and len == 2. Amount of memory leaked
scales with the size of this buffer. For example, the following
eternal loop leaks 20 bytes per iteration, so run it with caution:

s//'x' ^ -"s666666666666666k:\347"/eeg while (1)

[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
    category=core
    severity=medium
---
Site configuration information for perl 5.25.9:

Configured by root at Sat Jan 14 02:25:05 MSK 2017.

Summary of my perl5 (revision 5 version 25 subversion 9) configuration:
  Commit id: cbe2fc5001aa59cdc73e04cc35e097a2ecfbeec0
  Platform:
    osname=linux
    osvers=3.16.0-4-amd64
    archname=x86_64-linux
    uname='linux dorothy 3.16.0-4-amd64 #1 smp debian 3.16.36-1+deb8u2
(2016-10-19) x86_64 gnulinux '
    config_args='-des -Dusedevel -DDEBUGGING -Dcc=afl-clang-fast
-Doptimize=-O0 -g -ggdb3'
    hint=recommended
    useposix=true
    d_sigaction=define
    useithreads=undef
    usemultiplicity=undef
    use64bitint=define
    use64bitall=define
    uselongdouble=undef
    usemymalloc=n
    bincompat5005=undef
  Compiler:
    cc='afl-clang-fast'
    ccflags ='-DDEBUGGING -fno-strict-aliasing -pipe
-fstack-protector-strong -I/usr/local/include -D_LARGEFILE_SOURCE
-D_FILE_OFFSET_BITS=64 -D_FORTIFY_SOURCE=2'
    optimize='-O0 -g -ggdb3'
    cppflags='-DDEBUGGING -fno-strict-aliasing -pipe
-fstack-protector-strong -I/usr/local/include'
    ccversion=''
    gccversion='4.2.1 Compatible Clang 3.9.1 (tags/RELEASE_391/rc2)'
    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='double'
    nvsize=8
    Off_t='off_t'
    lseeksize=8
    alignbytes=8
    prototype=define
  Linker and Libraries:
    ld='afl-clang-fast'
    ldflags =' -fstack-protector-strong -L/usr/local/lib'
    libpth=/usr/local/lib /usr/lib/llvm-3.9/bin/../lib/clang/3.9.1/lib
/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-2.24.so
    so=so
    useshrplib=false
    libperl=libperl.a
    gnulibc_version='2.24'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs
    dlext=so
    d_dlsymun=undef
    ccdlflags='-Wl,-E'
    cccdlflags='-fPIC'
    lddlflags='-shared -O0 -g -ggdb3 -L/usr/local/lib -fstack-protector-strong'


---
@INC for perl 5.25.9:
    lib
    /usr/local/lib/perl5/site_perl/5.25.9/x86_64-linux
    /usr/local/lib/perl5/site_perl/5.25.9
    /usr/local/lib/perl5/5.25.9/x86_64-linux
    /usr/local/lib/perl5/5.25.9

---
Environment for perl 5.25.9:
    HOME=/home/afl
    LANG=en_US.UTF-8
    LANGUAGE=en_US:en
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/afl/perlbrew/bin:/home/afl/perlbrew/perls/perl-5.22.1/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games
    PERLBREW_BASHRC_VERSION=0.78
    PERLBREW_HOME=/home/afl/.perlbrew
    PERLBREW_MANPATH=/home/afl/perlbrew/perls/perl-5.22.1/man
    PERLBREW_PATH=/home/afl/perlbrew/bin:/home/afl/perlbrew/perls/perl-5.22.1/bin
    PERLBREW_PERL=perl-5.22.1
    PERLBREW_ROOT=/home/afl/perlbrew
    PERLBREW_VERSION=0.78
    PERL_BADLANG (unset)
    SHELL=/usr/bin/zsh

• [perl #130632] Memory leak in Perl_yylex (toke.c:7027) by Sergey Aleynikov