Apply by doing:
       cd /usr/src
       patch -p0 < 033_execsubr.patch

And then rebuild your kernel.

Index: sys/kern/exec_subr.c
===================================================================
RCS file: /cvs/src/sys/kern/exec_subr.c,v
retrieving revision 1.7
diff -u -r1.7 exec_subr.c
--- sys/kern/exec_subr.c        1999/11/05 01:18:01     1.7
+++ sys/kern/exec_subr.c        2000/11/06 18:57:27
@@ -1,4 +1,4 @@
-/*     $OpenBSD: exec_subr.c,v 1.7 1999/11/05 01:18:01 mickey Exp $    */
+/*     $OpenBSD: exec_subr.c,v 1.9 2000/11/06 16:19:52 art Exp $       */
/*     $NetBSD: exec_subr.c,v 1.9 1994/12/04 03:10:42 mycroft Exp $    */

/*
@@ -154,12 +154,13 @@
        * map the vnode in using uvm_map.
        */

-       /* checks imported from uvm_mmap, needed? */
        if (cmd->ev_len == 0)
                return(0);
        if (cmd->ev_offset & PAGE_MASK)
                return(EINVAL);
       if (cmd->ev_addr & PAGE_MASK)
+               return(EINVAL);
+       if (cmd->ev_len & PAGE_MASK)
               return(EINVAL);

       /*