nscd: Null pointer crashes after notfound response

nscd: Null pointer crashes after notfound response

If the Name Service Cache Daemon's (nscd) cache fails to add a not-found

netgroup response to the cache, the client request can result in a null

pointer dereference. This flaw was introduced in glibc 2.15 when the

cache was added to nscd.

This vulnerability is only present in the nscd binary.