Fix multiple CVEs affecting Samba 4.9 port
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Release Announcements --------------------- These are security releases in order to address the following defects: o CVE-2018-14629 (Unprivileged adding of CNAME record causing loop in AD Internal DNS server) o CVE-2018-16841 (Double-free in Samba AD DC KDC with PKINIT) o CVE-2018-16851 (NULL pointer de-reference in Samba AD DC LDAP server) o CVE-2018-16852 (NULL pointer de-reference in Samba AD DC DNS servers) o CVE-2018-16853 (Samba AD DC S4U2Self crash in experimental MIT Kerberos configuration (unsupported)) o CVE-2018-16857 (Bad password count in AD DC not always effective) CVE-2018-16852 and CVE-2018-16857 affect 4.9 only. ======= Details ======= o CVE-2018-14629: All versions of Samba from 4.0.0 onwards are vulnerable to infinite query recursion caused by CNAME loops. Any dns record can be added via ldap by an unprivileged user using the ldbadd tool, so this is a security issue. o CVE-2018-16841: When configured to accept smart-card authentication, Samba's KDC will call talloc_free() twice on the same memory if the principal in a validly signed certificate does not match the principal in the AS-REQ. This is only possible after authentication with a trusted certificate. talloc is robust against further corruption from a double-free with talloc_free() and directly calls abort(), terminating the KDC process. There is no further vulnerability associated with this issue, merely a denial of service. o CVE-2018-16851: During the processing of an LDAP search before Samba's AD DC returns the LDAP entries to the client, the entries are cached in a single memory object with a maximum size of 256MB. When this size is reached, the Samba process providing the LDAP service will follow the NULL pointer, terminating the process. There is no further vulnerability associated with this issue, merely a denial of service. o CVE-2018-16852: During the processing of an DNS zone in the DNS management DCE/RPC server, the internal DNS server or the Samba DLZ plugin for BIND9, if the DSPROPERTY_ZONE_MASTER_SERVERS property or DSPROPERTY_ZONE_SCAVENGING_SERVERS property is set, the server will follow a NULL pointer and terminate. There is no further vulnerability associated with this issue, merely a denial of service. o CVE-2018-16853: A user in a Samba AD domain can crash the KDC when Samba is built in the non-default MIT Kerberos configuration. With this advisory we clarify that the MIT Kerberos build of the Samba AD DC is considered experimental. Therefore the Samba Team will not issue security patches for this configuration. o CVE-2018-16857: AD DC Configurations watching for bad passwords (to restrict brute forcing of passwords) in a window of more than 3 minutes may not watch for bad passwords at all. For more details and workarounds, please refer to the security advisories.