Assertion failure in Perl_leave_adjust_stacks (pp_hot.c:4653)

[p5pRT]

Migrated from rt.perl.org#133989 (status was 'pending release')

Searchable as RT133989$

[p5pRT]

From @dur-randir

Created by @dur-randir

While fuzzing perl v5.29.9-63-g2496d8f3f7 built with afl and run
under libdislocator, I found the following program

E{0;readline@​0}

to cause an assertion failure

perl​: pp_hot.c​:4653​: void Perl_leave_adjust_stacks(SV **, SV **, U8,
int)​: Assertion `nargs >= 0' failed.

GDB stack trace is following

#0 __GI_raise (sig=sig@​entry=6) at ../sysdeps/unix/sysv/linux/raise.c​:50
#1 0x00007ffff7c25535 in __GI_abort () at abort.c​:79
#2 0x00007ffff7c2540f in __assert_fail_base (fmt=0x7ffff7d87ee0
"%s%s%s​:%u​: %s%sAssertion `%s' failed.\n%n", assertion=0x555555aaa42a
"nargs >= 0",
  file=0x555555aa86e3 "pp_hot.c", line=4653, function=<optimized
out>) at assert.c​:92
#3 0x00007ffff7c330f2 in __GI___assert_fail (assertion=0x555555aaa42a
"nargs >= 0", file=0x555555aa86e3 "pp_hot.c", line=4653,
  function=0x555555aaae50 <__PRETTY_FUNCTION__.19610>
"Perl_leave_adjust_stacks") at assert.c​:101
#4 0x0000555555776529 in Perl_leave_adjust_stacks
(from_sp=0x555555b50da8, to_sp=0x555555b50da0, gimme=3 '\003', pass=3)
at pp_hot.c​:4653
#5 0x0000555555831c83 in Perl_pp_leave () at pp_ctl.c​:2133
#6 0x000055555570b640 in Perl_runops_debug () at dump.c​:2537
#7 0x00005555555ed560 in S_run_body (oldscope=1) at perl.c​:2716
#8 0x00005555555ecade in perl_run (my_perl=0x555555b4c260) at perl.c​:2639
#9 0x00005555555a114e in main (argc=3, argv=0x7fffffffe1c8,
env=0x7fffffffe1e8) at perlmain.c​:127

This is a regression between 5.22 and 5.24, bisect points to

commit 75bc488
Author​: David Mitchell <davem@​iabyn.com>
Date​: Thu Dec 17 12​:13​:09 2015 +0000

  replace leave_common() with leave_adjust_stacks()

  Make the remaining callers of S_leave_common() use leave_adjust_stacks()
  instead, then delete this static function.

  This brings the benefits of freeing TEMPS on all scope exists that
  has already been introduced on sub exits; uses the optimised code for
  creating mortal copies; and finally unifies all the different 'process
  return args on scope exit' implementations into single function.

Perl Info

Flags:
    category=core
    severity=medium

Site configuration information for perl 5.29.9:

Configured by dur-randir at Wed Feb 27 14:51:01 MSK 2019.

Summary of my perl5 (revision 5 version 29 subversion 9) configuration:
  Commit id: c1e47bad34ce1d9c84ed57c9b8978bcbd5a02e98
  Platform:
    osname=darwin
    osvers=13.4.0
    archname=darwin-thread-multi-2level
    uname='darwin isengard.local 13.4.0 darwin kernel version 13.4.0:
mon jan 11 18:17:34 pst 2016; root:xnu-2422.115.15~1release_x86_64
x86_64 '
    config_args='-de -Dusedevel -DDEBUGGING -Dusethreads'
    hint=recommended
    useposix=true
    d_sigaction=define
    useithreads=define
    usemultiplicity=define
    use64bitint=define
    use64bitall=define
    uselongdouble=undef
    usemymalloc=n
    default_inc_excludes_dot=define
    bincompat5005=undef
  Compiler:
    cc='cc'
    ccflags ='-fno-common -DPERL_DARWIN -mmacosx-version-min=10.9
-DDEBUGGING -fno-strict-aliasing -pipe -fstack-protector
-I/usr/local/include -DPERL_USE_SAFE_PUTENV'
    optimize='-O3 -g'
    cppflags='-fno-common -DPERL_DARWIN -mmacosx-version-min=10.9
-DDEBUGGING -fno-strict-aliasing -pipe -fstack-protector
-I/usr/local/include'
    ccversion=''
    gccversion='4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.56)'
    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='cc'
    ldflags =' -mmacosx-version-min=10.9 -fstack-protector -L/usr/local/lib'
    libpth=/usr/local/lib
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/clang/6.0/lib
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib
/usr/lib
    libs=-lpthread -lgdbm -ldbm -ldl -lm -lutil -lc
    perllibs=-lpthread -ldl -lm -lutil -lc
    libc=
    so=dylib
    useshrplib=false
    libperl=libperl.a
    gnulibc_version=''
  Dynamic Linking:
    dlsrc=dl_dlopen.xs
    dlext=bundle
    d_dlsymun=undef
    ccdlflags=' '
    cccdlflags=' '
    lddlflags=' -mmacosx-version-min=10.9 -bundle -undefined
dynamic_lookup -L/usr/local/lib -fstack-protector'



@INC for perl 5.29.9:
    lib
    /usr/local/lib/perl5/site_perl/5.29.9/darwin-thread-multi-2level
    /usr/local/lib/perl5/site_perl/5.29.9
    /usr/local/lib/perl5/5.29.9/darwin-thread-multi-2level
    /usr/local/lib/perl5/5.29.9


Environment for perl 5.29.9:
    DYLD_LIBRARY_PATH (unset)
    HOME=/Users/dur-randir
    LANG=en_US.UTF-8
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/Users/dur-randir/perlbrew/bin:/Users/dur-randir/perlbrew/perls/perl-5.22.1/bin:/usr/local/bin:/usr/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/texbin
    PERLBREW_HOME=/Users/dur-randir/.perlbrew
    PERLBREW_MANPATH=/Users/dur-randir/perlbrew/perls/perl-5.22.1/man
    PERLBREW_PATH=/Users/dur-randir/perlbrew/bin:/Users/dur-randir/perlbrew/perls/perl-5.22.1/bin
    PERLBREW_PERL=perl-5.22.1
    PERLBREW_ROOT=/Users/dur-randir/perlbrew
    PERLBREW_SHELLRC_VERSION=0.84
    PERLBREW_VERSION=0.84
    PERL_BADLANG (unset)
    SHELL=/usr/local/bin/zsh

[p5pRT]

From @tonycoz

On Fri, 05 Apr 2019 09​:26​:20 -0700, randir wrote​:

While fuzzing perl v5.29.9-63-g2496d8f3f7 built with afl and run
under libdislocator, I found the following program

E{0;readline@​0}

to cause an assertion failure

perl​: pp_hot.c​:4653​: void Perl_leave_adjust_stacks(SV **, SV **, U8,
int)​: Assertion `nargs >= 0' failed.

Patch attached.

Tony

[p5pRT]

From @tonycoz

0001-perl-133989-scalar-the-argument-to-readline-if-any.patch

From faa0ed849cf1bfe77c4cb9857dc3e8a0db0bfa7a Mon Sep 17 00:00:00 2001
From: Tony Cook <tony@develop-help.com>
Date: Wed, 12 Jun 2019 15:21:47 +1000
Subject: (perl #133989) scalar() the argument to readline, if any

C< readline @foo > would treat @foo as array.  If the array was empty
this would push zero items and readline() would then pop one item,
possibly underflowing the stack.
---
 op.c               | 1 +
 t/lib/croak/pp_sys | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/op.c b/op.c
index 6ad192307f..7aa002cadd 100644
--- a/op.c
+++ b/op.c
@@ -12142,6 +12142,7 @@ Perl_ck_readline(pTHX_ OP *o)
     if (o->op_flags & OPf_KIDS) {
 	 OP *kid = cLISTOPo->op_first;
 	 if (kid->op_type == OP_RV2GV) kid->op_private |= OPpALLOW_FAKE;
+         scalar(kid);
     }
     else {
 	OP * const newop
diff --git a/t/lib/croak/pp_sys b/t/lib/croak/pp_sys
index be100da27a..cf9e4ef0ed 100644
--- a/t/lib/croak/pp_sys
+++ b/t/lib/croak/pp_sys
@@ -93,3 +93,9 @@ close $fh;
 END { unlink $file; }
 EXPECT
 syswrite() isn't allowed on :utf8 handles at - line 5.
+########
+# NAME readline() didn't scalar() its argument
+# this would assert rather than failing on the method call
+E{0;readline@0}
+EXPECT
+Can't call method "E" without a package or object reference at - line 2.
-- 
2.11.0

[p5pRT]

The RT System itself - Status changed from 'new' to 'open'

[p5pRT]

From @tonycoz

On Tue, 11 Jun 2019 22​:22​:45 -0700, tonyc wrote​:

On Fri, 05 Apr 2019 09​:26​:20 -0700, randir wrote​:

While fuzzing perl v5.29.9-63-g2496d8f3f7 built with afl and run
under libdislocator, I found the following program

E{0;readline@​0}

to cause an assertion failure

perl​: pp_hot.c​:4653​: void Perl_leave_adjust_stacks(SV **, SV **, U8,
int)​: Assertion `nargs >= 0' failed.

Patch attached.

Applied as a8e0c1f.

Tony

[p5pRT]

@tonycoz - Status changed from 'open' to 'pending release'