Bug#296490: libc6: getgrnam segfault (using __nscd_getgrnam_r)

[Florian Weimer <fw@deneb.enyo.de>]

* Tom Parker:

> Calling getgrnam() with a NULL argument, with group in
> /etc/nsswitch.conf set to 'compat' can cause a segfault in
> __nscd_getgrnam_r due to a lack of a check for a NULL string before
> doing strlen().

Is there any standard that defines the behavior of getgrnam(NULL)?