From 13fe9f7f820d43400912b56aa6745a2b8007a514 Mon Sep 17 00:00:00 2001
From: Oleksandr Tymoshenko <gonzo@FreeBSD.org>
Date: Sun, 20 Jan 2019 19:47:33 +0000
Subject: [PATCH] Fix crash in systat(4) when certain commands are called
 without arguments

Add check for missing arguments to dsmatchselect and dsselect

PR:		219689
Submitted by:	Marko Turk <mt@markoturk.info>
MFC after:	1 week
---
 usr.bin/systat/devs.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/usr.bin/systat/devs.c b/usr.bin/systat/devs.c
index e6b1e48eb10e..e1c12eacbe74 100644
--- a/usr.bin/systat/devs.c
+++ b/usr.bin/systat/devs.c
@@ -193,6 +193,11 @@ dsmatchselect(const char *args, devstat_select_mode select_mode, int maxshowdevs
 	int i;
 	int retval = 0;
 
+	if (!args) {
+		warnx("dsmatchselect: no arguments");
+		return(0);
+	}
+
 	/*
 	 * Break the (pipe delimited) input string out into separate
 	 * strings.
@@ -251,6 +256,11 @@ dsselect(const char *args, devstat_select_mode select_mode, int maxshowdevs,
 	int i;
 	int retval = 0;
 
+	if (!args) {
+		warnx("dsselect: no argument");
+		return(1);
+	}
+
 	/*
 	 * If we've gone through this code before, free previously
 	 * allocated resources.