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Id: 131631
Status: open
Priority: 0/
Queue: perl5

Owner: Nobody
Requestors: randir <sergey.aleynikov [at]>

Operating System: (no value)
PatchStatus: (no value)
Severity: medium
Type: core
Perl Version: 5.27.1
Fixed In: (no value)

From: Sergey Aleynikov <sergey.aleynikov [...]>
Date: Thu, 22 Jun 2017 22:34:44 +0300
To: perlbug [...]
Subject: Segfault in Perl_cv_undef_flags
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This is a bug report for perl from, generated with the help of perlbug 1.40 running under perl 5.27.1. ----------------------------------------------------------------- [Please describe your issue here] While fuzzing perl v5.27.1-37-g4c95ee9f29 built with afl and run under libdislocator, I found the following program m|$0[sub{$0[o{warn]]]]|}} to crash, even when run under -c for a syntax check. GDB info about the crash location is: #0 0x0000564b247bd269 in Perl_cv_undef_flags (cv=0x564b257f8340, flags=0x0) at pad.c:398 398 U32 inner_rc = SvREFCNT(innercv); gdb$ bt #0 0x0000564b247bd269 in Perl_cv_undef_flags (cv=0x564b257f8340, flags=0x0) at pad.c:398 #1 0x0000564b247bc819 in Perl_cv_undef (cv=0x564b257f8340) at pad.c:289 #2 0x0000564b248e71ed in Perl_sv_clear (orig_sv=0x564b257f8340) at sv.c:6631 #3 0x0000564b248ea37e in Perl_sv_free2 (sv=0x564b257f8340, rc=0x1) at sv.c:7081 #4 0x0000564b24731e4a in S_SvREFCNT_dec (sv=0x564b257f8340) at inline.h:189 #5 0x0000564b2473301a in perl_destruct (my_perl=0x564b257f6010) at perl.c:867 #6 0x0000564b246effc7 in main (argc=0x2, argv=0x7ffd34abc078, env=0x7ffd34abc090) at perlmain.c:134 gdb$ p innercv $1 = (CV * const) 0x0 [Please do not change anything below this line] ----------------------------------------------------------------- --- Flags: category=core severity=medium --- Site configuration information for perl 5.27.1: Configured by root at Sun May 28 01:44:41 MSK 2017. Summary of my perl5 (revision 5 version 26 subversion 0) configuration: Derived from: 4c95ee9f298c2edfc1382d540ff89288790e78b6 Platform: osname=linux osvers=4.9.0-3-amd64 archname=x86_64-linux uname='linux dorothy 4.9.0-3-amd64 #1 smp debian 4.9.25-1 (2017-05-02) x86_64 gnulinux ' config_args='-des -Dusedevel -DDEBUGGING -Dcc=afl-clang-fast -Doptimize=-O0 -g -ggdb3 -fno-omit-frame-pointer' hint=previous 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='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 -fno-omit-frame-pointer' 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 /usr/local/lib /usr/lib/llvm-3.9/bin/../lib/clang/3.9.1/lib /usr/include/x86_64-linux-gnu /usr/lib libs=-lpthread -lnsl -ldl -lm -lcrypt -lutil -lc perllibs=-lpthread -lnsl -ldl -lm -lcrypt -lutil -lc 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 -fno-omit-frame-pointer -L/usr/local/lib -fstack-protector-strong' Locally applied patches: uncommitted-changes --- @INC for perl 5.27.1: lib /usr/local/lib/perl5/site_perl/5.26.0/x86_64-linux /usr/local/lib/perl5/site_perl/5.26.0 /usr/local/lib/perl5/5.26.0/x86_64-linux /usr/local/lib/perl5/5.26.0 --- Environment for perl 5.27.1: HOME=/home/afl LANG=en_US.UTF-8 LANGUAGE=en_US:en LC_CTYPE=en_US.UTF-8 LD_LIBRARY_PATH (unset) LOGDIR (unset) PATH=/home/afl/perlbrew/bin:/home/afl/perlbrew/perls/perl-5.24.1-dbg/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-5.24.1-dbg/man PERLBREW_PATH=/home/afl/perlbrew/bin:/home/afl/perlbrew/perls/perl-5.24.1-dbg/bin PERLBREW_PERL=perl-5.24.1-dbg PERLBREW_ROOT=/home/afl/perlbrew PERLBREW_VERSION=0.78 PERL_BADLANG (unset) SHELL=/usr/bin/zsh
Subject: Re: [perl #131631] Segfault in Perl_cv_undef_flags
From: Zefram <zefram [...]>
Date: Sat, 30 Dec 2017 12:40:33 +0000
To: perl5-porters [...]
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This is yet another bug based on parser error recovery screwing up stack synchronisation. I've converted the segv into an assertion failure in commit dce3f5c3fd788f1c2e451e3760f05a347c949eff, but the actual bug with error recovery remains. -zefram

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