SIGCHLD race condition?

[Carson Gaspar]

There is another race (from serverloop.c):

                if (child_terminated) {
                        while ((pid = waitpid(-1, &status, WNOHANG)) > 0)
                                session_close_by_pid(pid, status);
                        child_terminated = 0;
                }

It is possible to loose a child under the following situation:

- wait for all children
- receive SIGCHLD, handler sets child_terminated to 1
- main code sets child_terminated to 0

You must block SIGCHLD delivery before the while loop, and unblock after 
the assignment.

NOTE: You'll _probably_ only ever see this race on SMP systems, and even 
then the race is very small.

-- 
Carson