Bug #10296: SEGV from unchecked Data_Get_Struct() argument

• Status: Closed
• Priority: Normal
• Assignee: -
• Target version: -
• ruby -v: ruby 2.1.3p242 (2014-09-19 revision 47630) [x86_64-darwin13.0]
• Backport: 2.1: REQUIRED

[jhaberman (Josh Haberman)]

I can crash all Ruby versions I tried with this program:

require 'json'
require 'zlib'
 
module JSON
  module Ext
    module Generator
      class State
        def foo
          initialize_copy(Zlib::GzipWriter.new('foo.gz'))
        end
      end
    end
  end
end
 
state = JSON::Ext::Generator::State.new.foo

[normalperson (Eric Wong)]

Calling initialize_copy directly is probably buggy behavior and not
unique to just the json/zlib C extensions.

Other than telling users to never call initialize_copy directly, I'm not
sure what to do about it. It would be a lot of effort to fix every
existing extension out there.

Moving towards rb_data_type_t should allow CRuby to enforce this
transparently.

Maybe other folks have better ideas...

[jhaberman (Josh Haberman)]

Yes it seems like all uses of Data_Get_Struct() should be changed to use TypedData_Get_Struct() instead, doesn't it? TypedData* seems like a strictly better interface and it can provide type checking.

There are probably other instances of this in the standard library that don't involve initialize_copy.

[hsbt (Hiroshi SHIBATA)]

• Description updated (diff)

It still happens with 2.1.10.

[nobu (Nobuyoshi Nakada)]

• Description updated (diff)
• Status changed from Open to Closed
• Backport changed from 2.0.0: UNKNOWN, 2.1: UNKNOWN to 2.1: REQUIRED

It doesn't happen with 2.2.5.