[SECURITY] libidn - locale specific error in test suite

[Eric Blake]

On 01/18/2017 09:23 AM, Eric Blake wrote:
> On 01/18/2017 06:12 AM, Dr. Volker Zell wrote:
> 
>>>>
>>>> The source code can be found in the file (after unpacking of
>>>> https://ftp.gnu.org/gnu/libidn/libidn-1.33.tar.gz)
>>>>
>>>>  o
>>>> .../libidn-1.33-1.x86_64/src/libidn-1.33/lib/gltests/test-localename.c
>>>
>>> Do you have a self-contained testcase, by any chance?
>>
>> No, just the testcase from the testsuite in libidn.
> 
> The test comes from gnulib, so I'm familiar with ideas on how to try and
> whittle it down to a smaller self-contained test.  I'll see if I can
> spend a moment on it today.
> 

After stepping through a debugger, it looks like this is a bug in gnulib
and not cygwin.  Gnulib is trying to test that its own function
gl_locale_name() can track the use of uselocale() to set a thread-local
locale that overrides the global locale.  It has platform specific code
for various platforms (glibc uses nl_langinfo(), BSD uses querylocale(),
Sun uses getlocalename_l() - surprisingly none of the platforms use
nl_langinfo_l()!), then falls back to probing the environment.  As long
as cygwin lacked uselocale(), then probing the environment was correct.
But now that cygwin supports uselocale(), the gnulib code needs to add a
cygwin-specific clause to its list of various platform methods.

I'll propose a patch to upstream gnulib, and cc this list - any project
using gnulib will have to backport that patch or wait for a new upstream
release of that project that uses newer gnulib if it wants to work
around the bug.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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