diff -urNad proftpd-dfsg-1.3.0~/src/auth.c proftpd-dfsg-1.3.0/src/auth.c

--- proftpd-dfsg-1.3.0~/src/auth.c	2007-04-17 23:38:06.000000000 +0200

+++ proftpd-dfsg-1.3.0/src/auth.c	2007-04-17 23:38:50.000000000 +0200

@@ -64,27 +64,38 @@

 }

 static modret_t *dispatch_auth(cmd_rec *cmd, char *match) {

-  authtable *authtab = NULL;

+  authtable *start_tab = NULL, *iter_tab = NULL;

   modret_t *mr = NULL;

-  authtab = pr_stash_get_symbol(PR_SYM_AUTH, match, NULL,

+  start_tab = pr_stash_get_symbol(PR_SYM_AUTH, match, NULL,

     &cmd->stash_index);

+  iter_tab = start_tab;

+

+  while (iter_tab) {

+    pr_signals_handle();

-  while (authtab) {

     pr_log_debug(DEBUG6, "dispatching auth request \"%s\" to module mod_%s",

-      match, authtab->m->name);

+      match, iter_tab->m->name);

-    mr = call_module(authtab->m, authtab->handler, cmd);

+    mr = call_module(iter_tab->m, iter_tab->handler, cmd);

-    if (authtab->auth_flags & PR_AUTH_FL_REQUIRED)

+    if (iter_tab->auth_flags & PR_AUTH_FL_REQUIRED)

       break;

     if (MODRET_ISHANDLED(mr) ||

         MODRET_ISERROR(mr))

       break;

-    authtab = pr_stash_get_symbol(PR_SYM_AUTH, match, authtab,

+    iter_tab = pr_stash_get_symbol(PR_SYM_AUTH, match, iter_tab,

       &cmd->stash_index);

+ 

+     if (iter_tab == start_tab) {

+       /* We have looped back to the start.  Break out now and do not loop

+        * around again (and again, and again...)

+        */

+       mr = PR_DECLINED(cmd);

+       break;

+     }

   }

   return mr;