Fix checks for tainted dir in $ENV{PATH}

$ cat > foo
#!/usr/bin/perl
print "What?!\n"
^D
$ chmod +x foo
$ ./perl -Ilib -Te '$ENV{PATH}="."; exec "foo"'
Insecure directory in $ENV{PATH} while running with -T switch at -e line 1.

That is what I expect to see.  But:

$ ./perl -Ilib -Te '$ENV{PATH}="/\\:."; exec "foo"'
What?!

Perl is allowing the \ to escape the :, but the \ is not treated as an
escape by the system, allowing a relative path in PATH to be consid-
ered safe.

1 files changed, 1 insertions, 0 deletions

diff --git a/embed.h b/embed.h
index 8220ab567d..8be5109a28 100644
--- a/embed.h
+++ b/embed.h
@@ -1216,6 +1216,7 @@
 #define deb_stack_all()		Perl_deb_stack_all(aTHX)
 #define defelem_target(a,b)	Perl_defelem_target(aTHX_ a,b)
 #define delete_eval_scope()	Perl_delete_eval_scope(aTHX)
+#define delimcpy_no_escape	Perl_delimcpy_no_escape
 #define die_unwind(a)		Perl_die_unwind(aTHX_ a)
 #define do_aexec5(a,b,c,d,e)	Perl_do_aexec5(aTHX_ a,b,c,d,e)
 #define do_dump_pad(a,b,c,d)	Perl_do_dump_pad(aTHX_ a,b,c,d)