commit 05c544eef3633b774ca38154ba4c2bf3416b471b

Author: Tom Yu <tlyu@mit.edu>

Date:   Mon Nov 4 15:33:09 2013 -0500

    Multi-realm KDC null deref [CVE-2013-1418]

    If a KDC serves multiple realms, certain requests can cause

    setup_server_realm() to dereference a null pointer, crashing the KDC.

    CVSSv2: AV:N/AC:M/Au:N/C:N/I:N/A:P/E:POC/RL:OF/RC:C

    A related but more minor vulnerability requires authentication to

    exploit, and is only present if a third-party KDC database module can

    dereference a null pointer under certain conditions.

    (back ported from commit 5d2d9a1abe46a2c1a8614d4672d08d9d30a5f8bf)

    ticket: 7756 (new)

    version_fixed: 1.11.4

    status: resolved

diff --git a/src/kdc/main.c b/src/kdc/main.c

index 1624046..8a085a2 100644

--- a/src/kdc/main.c

+++ b/src/kdc/main.c

@@ -125,6 +125,9 @@ setup_server_realm(struct server_handle *handle, krb5_principal sprinc)

     int kdc_numrealms = handle->kdc_numrealms;

     kret = 0;

+    if (sprinc == NULL)

+        return NULL;

+

     if (kdc_numrealms > 1) {

         if (!(newrealm = find_realm_data(handle, sprinc->realm.data,

                                          (krb5_ui_4) sprinc->realm.length)))