Bug 625893 (CVE-2011-1095)

Harald van Dijk discovered [1],[2] that glibc's locale command does not sufficiently sanitize the user environment.  According to POSIX specifications [3], the output of the 'locale' command must be appropriately quoted and safe to execute, in order to restore the locale after temporarily forcing a change (such as LC_ALL=C).  However, this is not the case with glibc versions up to and including 2.12.1:

LANG=' rm -rf /' locale
locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_MESSAGES to default locale: No such file or directory
locale: Cannot set LC_ALL to default locale: No such file or directory
LANG= rm -rf /
LC_CTYPE=" rm -rf /"
LC_NUMERIC=" rm -rf /"
LC_TIME=" rm -rf /"
LC_COLLATE=" rm -rf /"
LC_MONETARY=" rm -rf /"
LC_MESSAGES=" rm -rf /"
LC_PAPER=" rm -rf /"
LC_NAME=" rm -rf /"
LC_ADDRESS=" rm -rf /"
LC_TELEPHONE=" rm -rf /"
LC_MEASUREMENT=" rm -rf /"
LC_IDENTIFICATION=" rm -rf /"
LC_ALL=

Any script that does "eval $(locale)" or something similar will execute the unquoted commands.

The POSIX specification states:

"The <value> and <implied value> shown above shall be properly quoted for possible later reentry to the shell. The <value> shall not be quoted using double-quotes (so that it can be distinguished by the user from the <implied value> case, which always requires double-quotes)."

This has been corrected upstream [4].

[1] http://bugs.gentoo.org/show_bug.cgi?id=330923
[2] http://sources.redhat.com/bugzilla/show_bug.cgi?id=11904
[3] http://www.opengroup.org/onlinepubs/000095399/utilities/locale.html
[4] http://sourceware.org/git/?p=glibc.git;a=patch;h=026373745eab50a683536d950cb7e17dc98c4259