Bug#411786: tainted $@ taints utf8 substitution result

[Niko Tyni]

This is a bug report for perl from Niko Tyni <ntyni at debian.org>,
generated with the help of perlbug 1.39 running under perl 5.11.4.


-----------------------------------------------------------------
When $@ is tainted, the result of a regexp substitution on an
utf8 string becomes tainted too for no apparent reason.

Seen on at least from 5.8.8 up to current blead.

#!perl -T
use Scalar::Util q/tainted/;
$@=$ENV{HOME}; # taint errsv
$f = "out/abc\x{263A}"; # set the utf8 flag
print tainted($f), "\n";
$f =~s!/*[^/]+$!!;
print tainted($f), "\n";
__END__

gives 

0
1

when I'd expect

0
0

(Originally reported as http://bugs.debian.org/411786 ) 

-----------------------------------------------------------------
---
Flags:
    category=core
    severity=low
---
Site configuration information for perl 5.11.4:

Configured by niko at Mon Jan 25 19:04:36 EET 2010.

Summary of my perl5 (revision 5 version 11 subversion 4) configuration:
  Commit id: fe61459e95657c432074058bd8854fec03559335
  Platform:
    osname=linux, osvers=2.6.32-trunk-amd64, archname=x86_64-linux-gnu-thread-multi
    uname='linux madeleine 2.6.32-trunk-amd64 #1 smp sun jan 10 22:40:40 utc 2010 x86_64 gnulinux '
    config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN -Dcccdlflags=-fPIC -Darchname=x86_64-linux-gnu -Dprefix=/usr -Dprivlib=/usr/share/perl/5.11 -Darchlib=/usr/lib/perl/5.11 -Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.11.4 -Dsitearch=/usr/local/lib/perl/5.11.4 -Dman1dir=/usr/share/man/man1 -Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1 -Dsiteman3dir=/usr/local/man/man3 -Dman1ext=1 -Dman3ext=3perl -Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Ud_ualarm -Uusesfio -Uusenm -DDEBUGGING=both -Doptimize=-O0 -Dusedevel -Uuseshrplib -des'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=define, usemultiplicity=define
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=define, use64bitall=define, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -DDEBUGGING -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O0 -g',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -DDEBUGGING -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include'
    ccversion='', gccversion='4.4.3 20100108 (prerelease)', gccosandvers=''
    intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
    ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =' -fstack-protector -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib /lib64 /usr/lib64
    libs=-lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lpthread -lc -lgdbm_compat
    perllibs=-lnsl -ldl -lm -lcrypt -lutil -lpthread -lc
    libc=/lib/libc-2.10.2.so, so=so, useshrplib=false, libperl=libperl.a
    gnulibc_version='2.10.2'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -O0 -g -L/usr/local/lib -fstack-protector'

Locally applied patches:
    

---
@INC for perl 5.11.4:
    lib
    /usr/local/lib/perl/5.11.4
    /usr/local/share/perl/5.11.4
    /usr/lib/perl5
    /usr/share/perl5
    /usr/lib/perl/5.11
    /usr/share/perl/5.11
    .

---
Environment for perl 5.11.4:
    HOME=/home/niko
    LANG=en_US.UTF-8
    LANGUAGE (unset)
    LC_CTYPE=fi_FI.UTF-8
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/niko/bin:/home/niko/bin:/home/niko/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games:/sbin:/usr/sbin:/sbin:/usr/sbin
    PERL_BADLANG (unset)
    SHELL=/bin/zsh