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.

References

• https://nvd.nist.gov/vuln/detail/CVE-2024-33600
• https://sourceware.org/git/?p=glibc.git;a=blob;f=advisories/GLIBC-SA-2024-0006
• https://security.netapp.com/advisory/ntap-20240524-0013
• https://lists.debian.org/debian-lts-announce/2024/06/msg00026.html
• http://www.openwall.com/lists/oss-security/2024/07/22/5