Guard against a NULL mod_name

* Guard against a NULL mod_name in getModName and return undef.  Thanks,
  Sergio Gelato.  (Closes: #670517)

debian/changelog

 libheimdal-kadm5-perl (0.08-5) UNRELEASED; urgency=medium
 
+  * Guard against a NULL mod_name in getModName and return undef.  Thanks,
+    Sergio Gelato.  (Closes: #670517)
   * Convert to a proper 3.0 (quilt) package with managed patches.
   * Contribute the package to the Debian Perl Group.
     - Change Maintainer to the group.

debian/patches/guard-against-null-mod-name.patch

+Description: Guard against NULL pointer dereference in krb5_unparse_name
+Author: Sergio Gelato <Sergio.Gelato@astro.su.se>
+
+--- a/Kadm5.xs
++++ b/Kadm5.xs
+@@ -737,14 +737,19 @@
+        char *p;
+        krb5_error_code ret;
+        
+-       ret = krb5_unparse_name(spp->handle->context,spp->principal.mod_name,&p);
+-       if (ret)
++       if (spp->principal.mod_name) 
++       {
++         ret = krb5_unparse_name(spp->handle->context,spp->principal.mod_name,&p);
++         if (ret)
+ 	 {
+ 	   safefree(p);
+ 	   croak("[Heimdal::Kadm5] krb5_unparse_name failed: %s\n",
+ 		 krb5_get_err_text(spp->handle->context, ret));
+ 	 }
+-       RETVAL = newSVpv(p,0);
++	 RETVAL = newSVpv(p,0);
++       }
++       else
++	 RETVAL = &PL_sv_undef;
+      }
+      OUTPUT:
+      RETVAL

debian/patches/series

 fix-library-calls.patch
+guard-against-null-mod-name.patch