[PATCH] CVE-2014-8121: Fix nss_files file management [BZ#18007]

[Florian Weimer]

* Andreas Schwab:

> Florian Weimer <fw@deneb.enyo.de> writes:
>
>> Sorry, I don't see how this can be retrofitted on top of the existing
>> NSS API.  It assumes that the NSS module keeps the iteration state in
>> a per-module global variable.
>
> That's the bug.

Maybe.  But we cannot remove the old API (there are external NSS
modules, after all).  Therefore, such a change would only increase
complexity.

If we had tests, I think a better first step would be to reduce code
duplication between the NSS modules glibc ships, and clean up the
#include file mess.  But without tests, such changes offer a poor
risk/benefit trade-off.

>> The fix I proposed builds on Ulrich's original patch which attempted
>> to separate the state for lookup and iteration, but failed to do so
>> because of that incorrectly initialized variable.
>
> There is no "incorrectly initialized variable".

Ahem, I think the commit message of my patch explains this quite
clearly.  The code Ulrich added to deal with this corner case didn't
work as intended because a flag was not set correctly.