should pledge(2) allow raise(3) and abort(3)?

[Theo Buehler]

While playing with Daniel Micay's malloc patches, I ran into a lot of
pledge aborts since pledge("stdio") disallows raise(3) and abort(3).
That's because raise sends the to 'pid + THREAD_PID_OFFSET' instead
of the pid itself.  The first sentence of the comment and the logic is
taken from kern_sig.c.

Index: /sys/kern/kern_pledge.c
===================================================================
RCS file: /var/cvs/src/sys/kern/kern_pledge.c,v
retrieving revision 1.97
diff -u -p -r1.97 kern_pledge.c
--- /sys/kern/kern_pledge.c     1 Nov 2015 19:03:33 -0000       1.97
+++ /sys/kern/kern_pledge.c     2 Nov 2015 10:24:35 -0000
@@ -1355,7 +1355,13 @@ pledge_kill(struct proc *p, pid_t pid)
                return 0;
        if (p->p_p->ps_pledge & PLEDGE_PROC)
                return 0;
-       if (pid == 0 || pid == p->p_pid)
+       /*
+        * If the target pid is > THREAD_PID_OFFSET then this
+        * must be a kill of another thread in the same process.
+        * This allows raise(3) and abort(3).
+        */
+       if (pid == 0 || p->p_pid == (pid > THREAD_PID_OFFSET ?
+           pid - THREAD_PID_OFFSET : pid))
                return 0;
        return pledge_fail(p, EPERM, PLEDGE_PROC);
 }