Issue #10568 has been reported by Balazs Kutil.

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Bug #10568: segmentation fault after pack & ioctl & unpack
https://bugs.ruby-lang.org/issues/10568

* Author: Balazs Kutil
* Status: Open
* Priority: Normal
* Assignee: Koichi Sasada
* Category: 
* Target version: 
* ruby -v: ruby 2.1.2p201 (2014-08-18 revision 47215) [x86_64-linux]
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN
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This snippet produces a segmentation fault on rubies on ruby_2_1 branch from git commit [1]
onwards and ruby_2_0_0 branch from commit [2] onwards. I was unable to reproduce the issue
on the current trunk [3]:
  
    require 'socket'
    SIOCETHTOOL = 0x8946
    i = ["lo", "\n"].pack("a16p")
    s = Socket.new(Socket::AF_INET, Socket::SOCK_DGRAM, 0)
    s.ioctl(SIOCETHTOOL, i)
    i.unpack("a16p")[1]

This patch [4] fixes the issue for both 2_1 and 2_0_0 branches, although the test case it contains
does not produce a segfault (only raises an ArgumentError) on affected revisions.

[1] [659fd08f](https://github.com/ruby/ruby/commit/659fd08fc093117cc9970ed4590fcd226d81244c)
[2] [c41f74cf](https://github.com/ruby/ruby/commit/c41f74cf4c7ea246ee605a75b1b5cf8fdf9b412b)
[3] [bc0f1312](https://github.com/ruby/ruby/commit/bc0f131277af6b6cd65a5e75c3b8a2d9d8b073ad)
[4] [4b146b25](https://github.com/ruby/ruby/commit/4b146b25333c52ca4503dfc3c4215b583e8e9963)



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