Add a simple test case that writes random garbage to (almost) every sysctl node.
This test reproduced already at least five unique panics in a few quick runs.
The test is skipped by default as it is not likely safe even without the panics.


(jruoho)

# $NetBSD: t_random_garbage.sh,v 1.1 2020/06/27 08:50:46 jruoho Exp $
#
# Copyright (c) 2020 The NetBSD Foundation, Inc.
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#
# This code is derived from software contributed to The NetBSD Foundation
# by Jukka Ruohonen.
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# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
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tmp="/tmp/sysctl.out"

getrint() {
	echo $(od -An -N2 -i /dev/urandom | sed 's/ //')
}

getrstr() {
	echo $(cat /dev/urandom | head -n 1 | base64)
}

atf_test_case random_garbage cleanup
random_garbage_head() {
	sysctl -a > $tmp
	atf_set "require.user" "root"
	atf_set "descr" "Test writing random garbage to sysctl nodes"
}

random_garbage_body() {

	atf_skip "The test is not safe"

	while read line; do

		var=$(echo $line | awk '{print $1}')

		case $var in
			kern.securelevel*)
			echo "Skipping $var"
			continue
			;;

			security*)
			echo "Skipping $var"
			continue
			;;
		esac

		val=$(getrint)
		echo "Write $var -> $val"
		sysctl -w $var=$val
		val=$(getrstr)
		echo "Write $var -> $val"
		sysctl -w $var=$val

	done < $tmp
}

random_garbage_cleanup() {

	atf_skip "The test is not safe"

	while read line; do
		var=$(echo $line | awk '{print $1}')
		val=$(echo $line | awk '{print $3}')
		echo "Restoring $var -> $val"
		sysctl -w $var=$val > /dev/null 2>&1
	done < $tmp

	rm $tmp
}

atf_init_test_cases() {
	atf_add_test_case random_garbage
}