SA-2011-006 KDC denial of service [CVE-2011-1527 CVE-2011-1528 CVE-20…

…11-1529]

Fix null pointer dereference and assertion failure conditions that
could cause a denial of service.

ticket: 6982
version_fixed: 1.9.2
status: resolved

git-svn-id: svn://anonsvn.mit.edu/krb5/branches/krb5-1-9@25369 dc483132-0cff-0310-8789-dd5450dbe970

src/plugins/kdb/db2/lockout.c

@@ -169,13 +169,25 @@ krb5_db2_lockout_audit(krb5_context context,
         return 0;
     }
 
+    if (entry == NULL)
+        return 0;
+
     if (!db_ctx->disable_lockout) {
         code = lookup_lockout_policy(context, entry, &max_fail,
                                      &failcnt_interval, &lockout_duration);
         if (code != 0)
             return code;
     }
 
+    /*
+     * Don't continue to modify the DB for an already locked account.
+     * (In most cases, status will be KRB5KDC_ERR_CLIENT_REVOKED, and
+     * this check is unneeded, but in rare cases, we can fail with an
+     * integrity error or preauth failure before a policy check.)
+     */
+    if (locked_check_p(context, stamp, max_fail, lockout_duration, entry))
+        return 0;
+
     /* Only mark the authentication as successful if the entry
      * required preauthentication, otherwise we have no idea. */
     if (status == 0 && (entry->attributes & KRB5_KDB_REQUIRES_PRE_AUTH)) {

src/plugins/kdb/ldap/libkdb_ldap/ldap_principal2.c

@@ -105,6 +105,7 @@ krb5_ldap_get_principal(krb5_context context, krb5_const_principal searchfor,
     CHECK_LDAP_HANDLE(ldap_context);
 
     if (is_principal_in_realm(ldap_context, searchfor) != 0) {
+        st = KRB5_KDB_NOENTRY;
         krb5_set_error_message (context, st, "Principal does not belong to realm");
         goto cleanup;
     }

src/plugins/kdb/ldap/libkdb_ldap/lockout.c

@@ -165,6 +165,9 @@ krb5_ldap_lockout_audit(krb5_context context,
         return 0;
     }
 
+    if (entry == NULL)
+        return 0;
+
     if (!ldap_context->disable_lockout) {
         code = lookup_lockout_policy(context, entry, &max_fail,
                                      &failcnt_interval,
@@ -173,9 +176,16 @@ krb5_ldap_lockout_audit(krb5_context context,
             return code;
     }
 
-    entry->mask = 0;
+    /*
+     * Don't continue to modify the DB for an already locked account.
+     * (In most cases, status will be KRB5KDC_ERR_CLIENT_REVOKED, and
+     * this check is unneeded, but in rare cases, we can fail with an
+     * integrity error or preauth failure before a policy check.)
+     */
+    if (locked_check_p(context, stamp, max_fail, lockout_duration, entry))
+        return 0;
 
-    assert (!locked_check_p(context, stamp, max_fail, lockout_duration, entry));
+    entry->mask = 0;
 
     /* Only mark the authentication as successful if the entry
      * required preauthentication, otherwise we have no idea. */