This patch will upgrade Sudo version 1.8.25 to Sudo version 1.8.25
patchlevel 1.  To apply:

    $ cd sudo-1.8.25
    $ patch -p1 < sudo-1.8.25p1.patch

diff -urNa sudo-1.8.25/ChangeLog sudo-1.8.25p1/ChangeLog
--- sudo-1.8.25/ChangeLog	Sun Sep  2 06:31:27 2018
+++ sudo-1.8.25p1/ChangeLog	Wed Sep 12 09:08:33 2018
@@ -1,3 +1,19 @@
+2018-09-12  Todd C. Miller  <Todd.Miller@sudo.ws>
+
+	* doc/CONTRIBUTORS:
+	Add Kan Sasaki
+	[ff277fb5b0c9]
+
+	* NEWS, configure, configure.ac:
+	sudo 1.8.25p1
+	[c4f0a69e6356]
+
+	* lib/util/event_poll.c:
+	Fix a crash in the event system's poll() backend introduced with
+	support for nanosecond timers. Only affects systems without ppoll().
+	Bug #851
+	[54e561b11a0f]
+
 2018-09-02  Todd C. Miller  <Todd.Miller@sudo.ws>
 
 	* plugins/sudoers/po/sudoers.pot:
diff -urNa sudo-1.8.25/NEWS sudo-1.8.25p1/NEWS
--- sudo-1.8.25/NEWS	Sun Sep  2 06:30:08 2018
+++ sudo-1.8.25p1/NEWS	Wed Sep 12 09:07:23 2018
@@ -1,3 +1,9 @@
+What's new in Sudo 1.8.25p1
+
+ * Fixed a bug introduced in sudo 1.8.25 that caused a crash on
+   systems that have the poll() function but not the ppoll() function.
+   Bug #851.
+
 What's new in Sudo 1.8.25
 
  * Fixed a bug introduced in sudo 1.8.20 that broke formatting of
diff -urNa sudo-1.8.25/configure sudo-1.8.25p1/configure
--- sudo-1.8.25/configure	Sun Sep  2 06:30:08 2018
+++ sudo-1.8.25p1/configure	Wed Sep 12 09:07:23 2018
@@ -1,6 +1,6 @@
 #! /bin/sh
 # Guess values for system-dependent variables and create Makefiles.
-# Generated by GNU Autoconf 2.69 for sudo 1.8.25.
+# Generated by GNU Autoconf 2.69 for sudo 1.8.25p1.
 #
 # Report bugs to <https://bugzilla.sudo.ws/>.
 #
@@ -590,8 +590,8 @@
 # Identity of this package.
 PACKAGE_NAME='sudo'
 PACKAGE_TARNAME='sudo'
-PACKAGE_VERSION='1.8.25'
-PACKAGE_STRING='sudo 1.8.25'
+PACKAGE_VERSION='1.8.25p1'
+PACKAGE_STRING='sudo 1.8.25p1'
 PACKAGE_BUGREPORT='https://bugzilla.sudo.ws/'
 PACKAGE_URL=''
 
@@ -1542,7 +1542,7 @@
   # Omit some internal or obsolete options to make the list less imposing.
   # This message is too long to be a string in the A/UX 3.1 sh.
   cat <<_ACEOF
-\`configure' configures sudo 1.8.25 to adapt to many kinds of systems.
+\`configure' configures sudo 1.8.25p1 to adapt to many kinds of systems.
 
 Usage: $0 [OPTION]... [VAR=VALUE]...
 
@@ -1607,7 +1607,7 @@
 
 if test -n "$ac_init_help"; then
   case $ac_init_help in
-     short | recursive ) echo "Configuration of sudo 1.8.25:";;
+     short | recursive ) echo "Configuration of sudo 1.8.25p1:";;
    esac
   cat <<\_ACEOF
 
@@ -1872,7 +1872,7 @@
 test -n "$ac_init_help" && exit $ac_status
 if $ac_init_version; then
   cat <<\_ACEOF
-sudo configure 1.8.25
+sudo configure 1.8.25p1
 generated by GNU Autoconf 2.69
 
 Copyright (C) 2012 Free Software Foundation, Inc.
@@ -2581,7 +2581,7 @@
 This file contains any messages produced by compilers while
 running configure, to aid debugging if configure makes a mistake.
 
-It was created by sudo $as_me 1.8.25, which was
+It was created by sudo $as_me 1.8.25p1, which was
 generated by GNU Autoconf 2.69.  Invocation command line was
 
   $ $0 $@
@@ -27308,7 +27308,7 @@
 # report actual input values of CONFIG_FILES etc. instead of their
 # values after options handling.
 ac_log="
-This file was extended by sudo $as_me 1.8.25, which was
+This file was extended by sudo $as_me 1.8.25p1, which was
 generated by GNU Autoconf 2.69.  Invocation command line was
 
   CONFIG_FILES    = $CONFIG_FILES
@@ -27374,7 +27374,7 @@
 cat >>$CONFIG_STATUS <<_ACEOF || ac_write_fail=1
 ac_cs_config="`$as_echo "$ac_configure_args" | sed 's/^ //; s/[\\""\`\$]/\\\\&/g'`"
 ac_cs_version="\\
-sudo config.status 1.8.25
+sudo config.status 1.8.25p1
 configured by $0, generated by GNU Autoconf 2.69,
   with options \\"\$ac_cs_config\\"
 
diff -urNa sudo-1.8.25/configure.ac sudo-1.8.25p1/configure.ac
--- sudo-1.8.25/configure.ac	Sun Sep  2 06:30:09 2018
+++ sudo-1.8.25p1/configure.ac	Wed Sep 12 09:07:23 2018
@@ -4,7 +4,7 @@
 dnl Copyright (c) 1994-1996,1998-2018 Todd C. Miller <Todd.Miller@sudo.ws>
 dnl
 AC_PREREQ([2.59])
-AC_INIT([sudo], [1.8.25], [https://bugzilla.sudo.ws/], [sudo])
+AC_INIT([sudo], [1.8.25p1], [https://bugzilla.sudo.ws/], [sudo])
 AC_CONFIG_HEADER([config.h pathnames.h])
 AC_CONFIG_SRCDIR([src/sudo.c])
 dnl
diff -urNa sudo-1.8.25/doc/CONTRIBUTORS sudo-1.8.25p1/doc/CONTRIBUTORS
--- sudo-1.8.25/doc/CONTRIBUTORS	Sun Sep  2 06:30:09 2018
+++ sudo-1.8.25p1/doc/CONTRIBUTORS	Wed Sep 12 09:07:23 2018
@@ -131,6 +131,7 @@
     Sato, Yuichi
     Sánchez, Wilfredo
     Sanders, Miguel
+    Sasaki, Kan
     Saucier, Jean-Francois
     Schoenfeld, Patrick
     Schuring, Arno
diff -urNa sudo-1.8.25/lib/util/event_poll.c sudo-1.8.25p1/lib/util/event_poll.c
--- sudo-1.8.25/lib/util/event_poll.c	Sun Sep  2 06:30:08 2018
+++ sudo-1.8.25p1/lib/util/event_poll.c	Wed Sep 12 09:07:23 2018
@@ -144,7 +144,8 @@
 static int
 sudo_ev_poll(struct pollfd *fds, nfds_t nfds, const struct timespec *timo)
 {
-    const int timeout = (timo->tv_sec * 1000) + (timo->tv_nsec / 1000000);
+    const int timeout =
+	timo ? (timo->tv_sec * 1000) + (timo->tv_nsec / 1000000) : -1;
 
     return poll(fds, nfds, timeout);
 }