Issue #12666 has been updated by shyouhei (Shyouhei Urabe).

Status changed from Feedback to Closed

Thank you for confirmation.

vo.x (Vit Ondruch) wrote in #note-9:
> Well, we don't have PPC64 just PPC64LE on Fedora. I have run 5 builds and all passed just fine.

OK then, let me close this.  Don't hesitate to reopen when something happens again.

>  Nevertheless, this is what glibc maintainers said about the issue [1]:
(...snip...)
> >This is an application defect.

Yes.  However,

> >If you're using a path it's expected you know what you're loading.
> >
> >One _should_ be using '#include <gnu/lib-names.h>' to get LIBC_SO and then dlopen that, it's the only supported solution, particularly consider distributions
> >that might have /usr/lib64, or multi-arched lib dirs. You could be loading libc.so.6 from an incompatible ABI.

This doesn't work for non-glibc situations including *BSD, musl, etc.

> >Loding by SONAME is the only safe option.
> 
> IOW, I don't think there should be the path magic.

If the world is built on top of glibc, then yes.  We can omit the entire libc detection routine.  But the reality is not.

----------------------------------------
Bug #12666: Fatal error: glibc detected an invalid stdio handle
https://bugs.ruby-lang.org/issues/12666#change-84935

* Author: vo.x (Vit Ondruch)
* Status: Closed
* Priority: Normal
* Assignee: tenderlovemaking (Aaron Patterson)
* ruby -v: ruby 2.3.1p112 (2016-04-26 revision 54768) [powerpc64-linux]
* Backport: 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN
----------------------------------------
During build of Ruby for Fedora on PPC64, there is reported following error:

```
Fiddle::TestImport#test_io = Fatal error: glibc detected an invalid stdio handle
uncommon.mk:612: recipe for target 'yes-test-almost' failed
make: *** [yes-test-almost] Aborted (core dumped)
```

and this is the analysis of one of glibc maintainers:

```
libio vtable verification fails because there are two copies of libc.so.6 in the process:

	0x00003fffb79413a8 - 0x00003fffb7941f78 is __libc_IO_vtables in /lib64/power8/libc.so.6
	0x00003fffb74213c0 - 0x00003fffb7421f90 is __libc_IO_vtables in /lib64/libc.so.6

IO.pipe refers to a vtable from a the first copy, but the fprintf called via libffi comes from the second copy.

The root cause is the Fiddle module loading libc.so.6 with an absolute path:

#0  __dlopen (file=0x20728280 "/lib64/libc.so.6", mode=257) at dlopen.c:75
#1  0x00003fffb748782c in rb_fiddle_handle_initialize (argc=<optimized out>, argv=<optimized out>, self=544821280) at handle.c:179

This comes from test/fiddle/helper.rb:

when /x86_64-linux/
  libc_so = "/lib64/libc.so.6"
  libm_so = "/lib64/libm.so.6"
when /linux/
  libdir = '/lib'
  case [0].pack('L!').size
  when 4
    # 32-bit ruby
    libdir = '/lib32' if File.directory? '/lib32'
  when 8
    # 64-bit ruby
    libdir = '/lib64' if File.directory? '/lib64'
  end
  libc_so = File.join(libdir, "libc.so.6")
  libm_so = File.join(libdir, "libm.so.6")

So the good news is that it's just a path.  I expect the fix looks like this:

when /linux/
  libc_so = "libc.so.6"
  libm_so = "libm.so.6"

(This replaces tehe x86_64-linux branch, too.)
```

Please also note that:

```
libio vtable verification is a new security hardening feature in Fedora 25.
```

To workaround this error, I am going to apply following patch to Fedora:

```
From 346e147ba6480839b87046e9a9efab0bf6ed3660 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?V=C3=ADt=20Ondruch?= <vondruch / redhat.com>
Date: Wed, 10 Aug 2016 17:35:48 +0200
Subject: [PATCH] Rely on ldd to detect glibc.

This is just workaround, since we know we are quite sure this will be successful
on Red Hat platforms.

This workaround rhbz#1361037
---
 test/fiddle/helper.rb | 92 ---------------------------------------------------
 1 file changed, 92 deletions(-)

diff --git a/test/fiddle/helper.rb b/test/fiddle/helper.rb
index 1da3d93..65148a1 100644
--- a/test/fiddle/helper.rb
+++ b/test/fiddle/helper.rb
@@ -6,98 +6,6 @@
 
 libc_so = libm_so = nil
 
-case RUBY_PLATFORM
-when /cygwin/
-  libc_so = "cygwin1.dll"
-  libm_so = "cygwin1.dll"
-when /x86_64-linux/
-  libc_so = "/lib64/libc.so.6"
-  libm_so = "/lib64/libm.so.6"
-when /linux/
-  libdir = '/lib'
-  case [0].pack('L!').size
-  when 4
-    # 32-bit ruby
-    libdir = '/lib32' if File.directory? '/lib32'
-  when 8
-    # 64-bit ruby
-    libdir = '/lib64' if File.directory? '/lib64'
-  end
-  libc_so = File.join(libdir, "libc.so.6")
-  libm_so = File.join(libdir, "libm.so.6")
-when /mingw/, /mswin/
-  require "rbconfig"
-  crtname = RbConfig::CONFIG["RUBY_SO_NAME"][/msvc\w+/] || 'ucrtbase'
-  libc_so = libm_so = "#{crtname}.dll"
-when /darwin/
-  libc_so = "/usr/lib/libc.dylib"
-  libm_so = "/usr/lib/libm.dylib"
-when /kfreebsd/
-  libc_so = "/lib/libc.so.0.1"
-  libm_so = "/lib/libm.so.1"
-when /gnu/	#GNU/Hurd
-  libc_so = "/lib/libc.so.0.3"
-  libm_so = "/lib/libm.so.6"
-when /mirbsd/
-  libc_so = "/usr/lib/libc.so.41.10"
-  libm_so = "/usr/lib/libm.so.7.0"
-when /freebsd/
-  libc_so = "/lib/libc.so.7"
-  libm_so = "/lib/libm.so.5"
-when /bsd|dragonfly/
-  libc_so = "/usr/lib/libc.so"
-  libm_so = "/usr/lib/libm.so"
-when /solaris/
-  libdir = '/lib'
-  case [0].pack('L!').size
-  when 4
-    # 32-bit ruby
-    libdir = '/lib' if File.directory? '/lib'
-  when 8
-    # 64-bit ruby
-    libdir = '/lib/64' if File.directory? '/lib/64'
-  end
-  libc_so = File.join(libdir, "libc.so")
-  libm_so = File.join(libdir, "libm.so")
-when /aix/
-  pwd=Dir.pwd
-  libc_so = libm_so = "#{pwd}/libaixdltest.so"
-  unless File.exist? libc_so
-    cobjs=%w!strcpy.o!
-    mobjs=%w!floats.o sin.o!
-    funcs=%w!sin sinf strcpy strncpy!
-    expfile='dltest.exp'
-    require 'tmpdir'
-    Dir.mktmpdir do |dir|
-      begin
-        Dir.chdir dir
-        %x!/usr/bin/ar x /usr/lib/libc.a #{cobjs.join(' ')}!
-        %x!/usr/bin/ar x /usr/lib/libm.a #{mobjs.join(' ')}!
-        %x!echo "#{funcs.join("\n")}\n" > #{expfile}!
-        require 'rbconfig'
-        if RbConfig::CONFIG["GCC"] = 'yes'
-          lflag='-Wl,'
-        else
-          lflag=''
-        end
-        flags="#{lflag}-bE:#{expfile} #{lflag}-bnoentry -lm"
-        %x!#{RbConfig::CONFIG["LDSHARED"]} -o #{libc_so} #{(cobjs+mobjs).join(' ')} #{flags}!
-      ensure
-        Dir.chdir pwd
-      end
-    end
-  end
-else
-  libc_so = ARGV[0] if ARGV[0] && ARGV[0][0] == ?/
-  libm_so = ARGV[1] if ARGV[1] && ARGV[1][0] == ?/
-  if( !(libc_so && libm_so) )
-    $stderr.puts("libc and libm not found: #{$0} <libc> <libm>")
-  end
-end
-
-libc_so = nil if !libc_so || (libc_so[0] == ?/ && !File.file?(libc_so))
-libm_so = nil if !libm_so || (libm_so[0] == ?/ && !File.file?(libm_so))
-
 if !libc_so || !libm_so
   ruby = EnvUtil.rubybin
   ldd = `ldd #{ruby}`
-- 
2.9.2
```

i.e. I am going to disable the custom code for detecting glibc on various platfors and rely just on ldd. My question is what should be the proper fix? Shouldn't be the ldd way the default behavior for Linux?

This issue was originally reported at:

https://bugzilla.redhat.com/show_bug.cgi?id=1361037




---Files--------------------------------
fiddle-path.diff (1.37 KB)


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