[sudo-workers] visudo regression

[Daniel Kopecek]

Hello,
  I've been notified about a regression in the visudo tool in respect to 
loops in alias definitions.
The reproducer looks like this:

# cat <<EOF >>/etc/sudoers
User_Alias YYY = FOO
User_Alias XXX = nobody
User_Alias FOO = XXX,YYY
FOO ALL=(ALL) NOPASSWD: ALL
EOF
# visudo -c
visudo: Warning: cycle in User_Alias `FOO'
Segmentation fault (core dumped)

It can be reproduced using the latest (1.8.6p4) release of sudo.

GDB backtrace: http://fpaste.org/3kWC/

Proposed patch:
-------
diff -up sudo-1.8.6p3/plugins/sudoers/visudo.c.cyclesegv sudo-1.8.6p3/plugins/sudoers/visudo.c
--- sudo-1.8.6p3/plugins/sudoers/visudo.c.cyclesegv     2013-01-23 12:15:32.493762418 +0100
+++ sudo-1.8.6p3/plugins/sudoers/visudo.c       2013-01-23 12:40:52.280432614 +0100
@@ -1075,18 +1075,16 @@ alias_remove_recursive(char *name, int t
      bool rval = true;
      debug_decl(alias_remove_recursive, SUDO_DEBUG_ALIAS)
  
-    if ((a = alias_find(name, type)) != NULL) {
+    if ((a = alias_remove(name, type)) != NULL) {
         tq_foreach_fwd(&a->members, m) {
             if (m->type == ALIAS) {
                 if (!alias_remove_recursive(m->name, type))
                     rval = false;
             }
         }
+       rbinsert(alias_freelist, a);
      }
      alias_seqno++;
-    a = alias_remove(name, type);
-    if (a)
-       rbinsert(alias_freelist, a);
      debug_return_bool(rval);
  }
-------

Dan K.