CVE-2014-0475: glibc directory traversal in LC_* locale handling

[Florian Weimer <fw () deneb enyo de>]

Stephane Chazelas discovered that directory traversal issue in locale
handling in glibc.  glibc accepts relative paths with ".." components
in the LC_* and LANG variables.  Together with typical OpenSSH
configurations (with suitable AcceptEnv settings in sshd_config), this
could conceivably be used to bypass ForceCommand restrictions (or
restricted shells), assuming the attacker has sufficient level of
access to a file system location on the host to create crafted locale
definitions there.

Bug report: https://sourceware.org/bugzilla/show_bug.cgi?id=17137

Git commits:

https://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=d183645616b
  Related alloca hardening (technically not covered by the CVE assignment)

https://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=4e8f95a0df7
  Actual fix

https://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=58536726692
  Documentation updates

(To backport the new test in a reliable fashion, you need to tweak the
Makefile to set the LOCPATH environment variable.)