Patch copied from upstream source repository:

https://github.com/shadow-maint/shadow/commit/67d2bb6e0a5ac124ce1f026dd5723217b1493194

From 67d2bb6e0a5ac124ce1f026dd5723217b1493194 Mon Sep 17 00:00:00 2001
From: Serge Hallyn <serge@hallyn.com>
Date: Sun, 18 Sep 2016 21:31:18 -0500
Subject: [PATCH] su.c: fix missing length argument to snprintf

---
 src/su.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/su.c b/src/su.c
index 0c50a9456afd..93ffd2fbe2b4 100644
--- a/src/su.c
+++ b/src/su.c
@@ -373,8 +373,8 @@ static void prepare_pam_close_session (void)
 		              stderr);
 		(void) kill (-pid_child, caught);
 
-		snprintf (kill_msg, _(" ...killed.\n"));
-		snprintf (wait_msg, _(" ...waiting for child to terminate.\n"));
+		snprintf (kill_msg, 256, _(" ...killed.\n"));
+		snprintf (wait_msg, 256, _(" ...waiting for child to terminate.\n"));
 
 		(void) signal (SIGALRM, kill_child);
 		(void) alarm (2);
-- 
2.11.0.rc2

