I ran into a case where the idmap winbindd paniced and resulted in a corrupted
winbindd_children list. The new idmap winbindd was forked and added to the list
before the SIGCHLD handler removed the old one from the list. When the function
winbind_child_died is finally called, the list is corrupted and results in an
infinite loop.

Adding a static child structure to the list that already contains the entry for
that (previous) child will corrupt the list as follows. Consider the list that
has 5 entries (as my case did).

List points to entry 1
Entry  next ptr   prev ptr
1       2         5
2       3         1  (this is the static idmap entry)
3       4         2
4       5         3
5       NULL      4

now when you attempt to insert entry 2 again you get the following
when DLIST_ADD does
   (p)->prev = (list)->prev; \   2 prev = 5
   (list)->prev = (p); \         1 prev = 2 
   (p)->next = (list); \         2 next = 1
   (list) = (p); \               List = 2

List points to entry 2
Entry  next ptr   prev ptr
1       2         2
2       1         5  (this is the static idmap entry)
3       4         2
4       5         3
5       NULL      4

You now have an infinite next loop from 2 to 1 and back