This is a bug report for perl from afl@dorothy,
generated with the help of perlbug 1.41 running under perl 5.31.5.

[Please describe your issue here]

While fuzzing perl v5.29.10-23-g7c0d7520a3 built with afl and run
under libdislocator, I found the following program

printf "%n0%n\x{100}", $_, 0

to cause a panic: sv_len_utf8 cache 0 real 1 for 0. This is broken from at least 5.16.3.

[Please do not change anything below this line]
Flags:
category=core
severity=medium
Site configuration information for perl 5.31.5:

Configured by root at Fri Oct 18 05:50:54 MSK 2019.

Summary of my perl5 (revision 5 version 31 subversion 5) configuration:
Derived from: 859b78b
Platform:
osname=linux
osvers=4.19.0-6-amd64
archname=x86_64-linux
uname='linux dorothy 4.19.0-6-amd64 #1 smp debian 4.19.67-2+deb10u1 (2019-09-20) x86_64 gnulinux '
config_args='-des -Dusedevel -Dcc=gcc -DDEBUGGING -Doptimize=-O0 -g -ggdb3'
hint=recommended
useposix=true
d_sigaction=define
useithreads=undef
usemultiplicity=undef
use64bitint=define
use64bitall=define
uselongdouble=undef
usemymalloc=n
default_inc_excludes_dot=define
bincompat5005=undef
Compiler:
cc='gcc'
ccflags ='-fwrapv -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='-fwrapv -DDEBUGGING -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include'
ccversion=''
gccversion='8.3.0'
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='double'
nvsize=8
Off_t='off_t'
lseeksize=8
alignbytes=8
prototype=define
Linker and Libraries:
ld='gcc'
ldflags =' -fstack-protector-strong -L/usr/local/lib'
libpth=/usr/local/lib /usr/lib/gcc/x86_64-linux-gnu/8/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-2.28.so
so=so
useshrplib=false
libperl=libperl.a
gnulibc_version='2.28'
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'

Characteristics of this binary (from libperl):
Compile-time options:
DEBUGGING
HAS_TIMES
PERLIO_LAYERS
PERL_COPY_ON_WRITE
PERL_DONT_CREATE_GVSV
PERL_MALLOC_WRAP
PERL_OP_PARENT
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_PERLIO
USE_PERL_ATOF
Locally applied patches:
uncommitted-changes
Built under linux
Compiled at Oct 18 2019 06:02:50
%ENV:
PERLBREW_BASHRC_VERSION="0.78"
PERLBREW_HOME="/home/afl/.perlbrew"
PERLBREW_MANPATH="/home/afl/perlbrew/perls/perl-5.20.2/man"
PERLBREW_PATH="/home/afl/perlbrew/bin:/home/afl/perlbrew/perls/perl-5.20.2/bin"
PERLBREW_PERL="perl-5.20.2"
PERLBREW_ROOT="/home/afl/perlbrew"
PERLBREW_VERSION="0.78"
@inc:
lib
/usr/local/lib/perl5/site_perl/5.31.5/x86_64-linux
/usr/local/lib/perl5/site_perl/5.31.5
/usr/local/lib/perl5/5.31.5/x86_64-linux
/usr/local/lib/perl5/5.31.5