Merge branch 'netconsole-selftest-for-userdata-overflow'

Breno Leitao says:

====================
netconsole: selftest for userdata overflow

Implement comprehensive testing for netconsole userdata entry handling,
demonstrating correct behavior when creating maximum entries and
preventing unauthorized overflow.

Refactor existing test infrastructure to support modular, reusable
helper functions that validate strict entry limit enforcement.

Also, add a warning if update_userdata() sees more than
MAX_USERDATA_ITEMS entries. This shouldn't happen and it is a bug that
shouldn't be silently ignored.

v2: https://lore.kernel.org/20250103-netcons_overflow_test-v2-0-a49f9be64c21@debian.org
v1: https://lore.kernel.org/20241204-netcons_overflow_test-v1-0-a85a8d0ace21@debian.org
====================

Link: https://patch.msgid.link/20250108-netcons_overflow_test-v3-0-3d85eb091bec@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

6 files changed, 298 insertions, 219 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index 42ac78507213..3f3e289b391c 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -16170,7 +16170,8 @@ M:	Breno Leitao <leitao@debian.org>
 S:	Maintained
 F:	Documentation/networking/netconsole.rst
 F:	drivers/net/netconsole.c
-F:	tools/testing/selftests/drivers/net/netcons_basic.sh
+F:	tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh
+F:	tools/testing/selftests/drivers/net/netcons\*
 
 NETDEVSIM
 M:	Jakub Kicinski <kuba@kernel.org>
diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index f422a2f666ef..86ab4a42769a 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -730,7 +730,7 @@ static void update_userdata(struct netconsole_target *nt)
 		struct userdatum *udm_item;
 		struct config_item *item;
 
-		if (child_count >= MAX_USERDATA_ITEMS)
+		if (WARN_ON_ONCE(child_count >= MAX_USERDATA_ITEMS))
 			break;
 		child_count++;
 
diff --git a/tools/testing/selftests/drivers/net/Makefile b/tools/testing/selftests/drivers/net/Makefile
index 0fec8f9801ad..469179c18935 100644
--- a/tools/testing/selftests/drivers/net/Makefile
+++ b/tools/testing/selftests/drivers/net/Makefile
@@ -1,11 +1,13 @@
 # SPDX-License-Identifier: GPL-2.0
 
 TEST_INCLUDES := $(wildcard lib/py/*.py) \
+		 $(wildcard lib/sh/*.sh) \
 		 ../../net/net_helper.sh \
 		 ../../net/lib.sh \
 
 TEST_PROGS := \
 	netcons_basic.sh \
+	netcons_overflow.sh \
 	ping.py \
 	queues.py \
 	stats.py \
diff --git a/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh b/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh
new file mode 100644
index 000000000000..3acaba41ac7b
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh
@@ -0,0 +1,225 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: GPL-2.0
+
+# This file contains functions and helpers to support the netconsole
+# selftests
+#
+# Author: Breno Leitao <leitao@debian.org>
+
+set -euo pipefail
+
+LIBDIR=$(dirname "$(readlink -e "${BASH_SOURCE[0]}")")
+
+SRCIF="" # to be populated later
+SRCIP=192.0.2.1
+DSTIF="" # to be populated later
+DSTIP=192.0.2.2
+
+PORT="6666"
+MSG="netconsole selftest"
+USERDATA_KEY="key"
+USERDATA_VALUE="value"
+TARGET=$(mktemp -u netcons_XXXXX)
+DEFAULT_PRINTK_VALUES=$(cat /proc/sys/kernel/printk)
+NETCONS_CONFIGFS="/sys/kernel/config/netconsole"
+NETCONS_PATH="${NETCONS_CONFIGFS}"/"${TARGET}"
+# NAMESPACE will be populated by setup_ns with a random value
+NAMESPACE=""
+
+# IDs for netdevsim
+NSIM_DEV_1_ID=$((256 + RANDOM % 256))
+NSIM_DEV_2_ID=$((512 + RANDOM % 256))
+NSIM_DEV_SYS_NEW="/sys/bus/netdevsim/new_device"
+
+# Used to create and delete namespaces
+source "${LIBDIR}"/../../../../net/lib.sh
+source "${LIBDIR}"/../../../../net/net_helper.sh
+
+# Create netdevsim interfaces
+create_ifaces() {
+
+	echo "$NSIM_DEV_2_ID" > "$NSIM_DEV_SYS_NEW"
+	echo "$NSIM_DEV_1_ID" > "$NSIM_DEV_SYS_NEW"
+	udevadm settle 2> /dev/null || true
+
+	local NSIM1=/sys/bus/netdevsim/devices/netdevsim"$NSIM_DEV_1_ID"
+	local NSIM2=/sys/bus/netdevsim/devices/netdevsim"$NSIM_DEV_2_ID"
+
+	# These are global variables
+	SRCIF=$(find "$NSIM1"/net -maxdepth 1 -type d ! \
+		-path "$NSIM1"/net -exec basename {} \;)
+	DSTIF=$(find "$NSIM2"/net -maxdepth 1 -type d ! \
+		-path "$NSIM2"/net -exec basename {} \;)
+}
+
+link_ifaces() {
+	local NSIM_DEV_SYS_LINK="/sys/bus/netdevsim/link_device"
+	local SRCIF_IFIDX=$(cat /sys/class/net/"$SRCIF"/ifindex)
+	local DSTIF_IFIDX=$(cat /sys/class/net/"$DSTIF"/ifindex)
+
+	exec {NAMESPACE_FD}</var/run/netns/"${NAMESPACE}"
+	exec {INITNS_FD}</proc/self/ns/net
+
+	# Bind the dst interface to namespace
+	ip link set "${DSTIF}" netns "${NAMESPACE}"
+
+	# Linking one device to the other one (on the other namespace}
+	if ! echo "${INITNS_FD}:$SRCIF_IFIDX $NAMESPACE_FD:$DSTIF_IFIDX"  > $NSIM_DEV_SYS_LINK
+	then
+		echo "linking netdevsim1 with netdevsim2 should succeed"
+		cleanup
+		exit "${ksft_skip}"
+	fi
+}
+
+function configure_ip() {
+	# Configure the IPs for both interfaces
+	ip netns exec "${NAMESPACE}" ip addr add "${DSTIP}"/24 dev "${DSTIF}"
+	ip netns exec "${NAMESPACE}" ip link set "${DSTIF}" up
+
+	ip addr add "${SRCIP}"/24 dev "${SRCIF}"
+	ip link set "${SRCIF}" up
+}
+
+function set_network() {
+	# setup_ns function is coming from lib.sh
+	setup_ns NAMESPACE
+
+	# Create both interfaces, and assign the destination to a different
+	# namespace
+	create_ifaces
+
+	# Link both interfaces back to back
+	link_ifaces
+
+	configure_ip
+}
+
+function create_dynamic_target() {
+	DSTMAC=$(ip netns exec "${NAMESPACE}" \
+		 ip link show "${DSTIF}" | awk '/ether/ {print $2}')
+
+	# Create a dynamic target
+	mkdir "${NETCONS_PATH}"
+
+	echo "${DSTIP}" > "${NETCONS_PATH}"/remote_ip
+	echo "${SRCIP}" > "${NETCONS_PATH}"/local_ip
+	echo "${DSTMAC}" > "${NETCONS_PATH}"/remote_mac
+	echo "${SRCIF}" > "${NETCONS_PATH}"/dev_name
+
+	echo 1 > "${NETCONS_PATH}"/enabled
+}
+
+function cleanup() {
+	local NSIM_DEV_SYS_DEL="/sys/bus/netdevsim/del_device"
+
+	# delete netconsole dynamic reconfiguration
+	echo 0 > "${NETCONS_PATH}"/enabled
+	# Remove all the keys that got created during the selftest
+	find "${NETCONS_PATH}/userdata/" -mindepth 1 -type d -delete
+	# Remove the configfs entry
+	rmdir "${NETCONS_PATH}"
+
+	# Delete netdevsim devices
+	echo "$NSIM_DEV_2_ID" > "$NSIM_DEV_SYS_DEL"
+	echo "$NSIM_DEV_1_ID" > "$NSIM_DEV_SYS_DEL"
+
+	# this is coming from lib.sh
+	cleanup_all_ns
+
+	# Restoring printk configurations
+	echo "${DEFAULT_PRINTK_VALUES}" > /proc/sys/kernel/printk
+}
+
+function set_user_data() {
+	if [[ ! -d "${NETCONS_PATH}""/userdata" ]]
+	then
+		echo "Userdata path not available in ${NETCONS_PATH}/userdata"
+		exit "${ksft_skip}"
+	fi
+
+	KEY_PATH="${NETCONS_PATH}/userdata/${USERDATA_KEY}"
+	mkdir -p "${KEY_PATH}"
+	VALUE_PATH="${KEY_PATH}""/value"
+	echo "${USERDATA_VALUE}" > "${VALUE_PATH}"
+}
+
+function listen_port_and_save_to() {
+	local OUTPUT=${1}
+	# Just wait for 2 seconds
+	timeout 2 ip netns exec "${NAMESPACE}" \
+		socat UDP-LISTEN:"${PORT}",fork "${OUTPUT}"
+}
+
+function validate_result() {
+	local TMPFILENAME="$1"
+
+	# TMPFILENAME will contain something like:
+	# 6.11.1-0_fbk0_rc13_509_g30d75cea12f7,13,1822,115075213798,-;netconsole selftest: netcons_gtJHM
+	#  key=value
+
+	# Check if the file exists
+	if [ ! -f "$TMPFILENAME" ]; then
+		echo "FAIL: File was not generated." >&2
+		exit "${ksft_fail}"
+	fi
+
+	if ! grep -q "${MSG}" "${TMPFILENAME}"; then
+		echo "FAIL: ${MSG} not found in ${TMPFILENAME}" >&2
+		cat "${TMPFILENAME}" >&2
+		exit "${ksft_fail}"
+	fi
+
+	if ! grep -q "${USERDATA_KEY}=${USERDATA_VALUE}" "${TMPFILENAME}"; then
+		echo "FAIL: ${USERDATA_KEY}=${USERDATA_VALUE} not found in ${TMPFILENAME}" >&2
+		cat "${TMPFILENAME}" >&2
+		exit "${ksft_fail}"
+	fi
+
+	# Delete the file once it is validated, otherwise keep it
+	# for debugging purposes
+	rm "${TMPFILENAME}"
+	exit "${ksft_pass}"
+}
+
+function check_for_dependencies() {
+	if [ "$(id -u)" -ne 0 ]; then
+		echo "This test must be run as root" >&2
+		exit "${ksft_skip}"
+	fi
+
+	if ! which socat > /dev/null ; then
+		echo "SKIP: socat(1) is not available" >&2
+		exit "${ksft_skip}"
+	fi
+
+	if ! which ip > /dev/null ; then
+		echo "SKIP: ip(1) is not available" >&2
+		exit "${ksft_skip}"
+	fi
+
+	if ! which udevadm > /dev/null ; then
+		echo "SKIP: udevadm(1) is not available" >&2
+		exit "${ksft_skip}"
+	fi
+
+	if [ ! -f "${NSIM_DEV_SYS_NEW}" ]; then
+		echo "SKIP: file ${NSIM_DEV_SYS_NEW} does not exist. Check if CONFIG_NETDEVSIM is enabled" >&2
+		exit "${ksft_skip}"
+	fi
+
+	if [ ! -d "${NETCONS_CONFIGFS}" ]; then
+		echo "SKIP: directory ${NETCONS_CONFIGFS} does not exist. Check if NETCONSOLE_DYNAMIC is enabled" >&2
+		exit "${ksft_skip}"
+	fi
+
+	if ip link show "${DSTIF}" 2> /dev/null; then
+		echo "SKIP: interface ${DSTIF} exists in the system. Not overwriting it." >&2
+		exit "${ksft_skip}"
+	fi
+
+	if ip addr list | grep -E "inet.*(${SRCIP}|${DSTIP})" 2> /dev/null; then
+		echo "SKIP: IPs already in use. Skipping it" >&2
+		exit "${ksft_skip}"
+	fi
+}
diff --git a/tools/testing/selftests/drivers/net/netcons_basic.sh b/tools/testing/selftests/drivers/net/netcons_basic.sh
index b175f4d966e5..fe765da498e8 100755
--- a/tools/testing/selftests/drivers/net/netcons_basic.sh
+++ b/tools/testing/selftests/drivers/net/netcons_basic.sh
@@ -18,224 +18,8 @@ set -euo pipefail
 
 SCRIPTDIR=$(dirname "$(readlink -e "${BASH_SOURCE[0]}")")
 
-# Simple script to test dynamic targets in netconsole
-SRCIF="" # to be populated later
-SRCIP=192.0.2.1
-DSTIF="" # to be populated later
-DSTIP=192.0.2.2
+source "${SCRIPTDIR}"/lib/sh/lib_netcons.sh
 
-PORT="6666"
-MSG="netconsole selftest"
-USERDATA_KEY="key"
-USERDATA_VALUE="value"
-TARGET=$(mktemp -u netcons_XXXXX)
-DEFAULT_PRINTK_VALUES=$(cat /proc/sys/kernel/printk)
-NETCONS_CONFIGFS="/sys/kernel/config/netconsole"
-NETCONS_PATH="${NETCONS_CONFIGFS}"/"${TARGET}"
-KEY_PATH="${NETCONS_PATH}/userdata/${USERDATA_KEY}"
-# NAMESPACE will be populated by setup_ns with a random value
-NAMESPACE=""
-
-# IDs for netdevsim
-NSIM_DEV_1_ID=$((256 + RANDOM % 256))
-NSIM_DEV_2_ID=$((512 + RANDOM % 256))
-NSIM_DEV_SYS_NEW="/sys/bus/netdevsim/new_device"
-
-# Used to create and delete namespaces
-source "${SCRIPTDIR}"/../../net/lib.sh
-source "${SCRIPTDIR}"/../../net/net_helper.sh
-
-# Create netdevsim interfaces
-create_ifaces() {
-
-	echo "$NSIM_DEV_2_ID" > "$NSIM_DEV_SYS_NEW"
-	echo "$NSIM_DEV_1_ID" > "$NSIM_DEV_SYS_NEW"
-	udevadm settle 2> /dev/null || true
-
-	local NSIM1=/sys/bus/netdevsim/devices/netdevsim"$NSIM_DEV_1_ID"
-	local NSIM2=/sys/bus/netdevsim/devices/netdevsim"$NSIM_DEV_2_ID"
-
-	# These are global variables
-	SRCIF=$(find "$NSIM1"/net -maxdepth 1 -type d ! \
-		-path "$NSIM1"/net -exec basename {} \;)
-	DSTIF=$(find "$NSIM2"/net -maxdepth 1 -type d ! \
-		-path "$NSIM2"/net -exec basename {} \;)
-}
-
-link_ifaces() {
-	local NSIM_DEV_SYS_LINK="/sys/bus/netdevsim/link_device"
-	local SRCIF_IFIDX=$(cat /sys/class/net/"$SRCIF"/ifindex)
-	local DSTIF_IFIDX=$(cat /sys/class/net/"$DSTIF"/ifindex)
-
-	exec {NAMESPACE_FD}</var/run/netns/"${NAMESPACE}"
-	exec {INITNS_FD}</proc/self/ns/net
-
-	# Bind the dst interface to namespace
-	ip link set "${DSTIF}" netns "${NAMESPACE}"
-
-	# Linking one device to the other one (on the other namespace}
-	if ! echo "${INITNS_FD}:$SRCIF_IFIDX $NAMESPACE_FD:$DSTIF_IFIDX"  > $NSIM_DEV_SYS_LINK
-	then
-		echo "linking netdevsim1 with netdevsim2 should succeed"
-		cleanup
-		exit "${ksft_skip}"
-	fi
-}
-
-function configure_ip() {
-	# Configure the IPs for both interfaces
-	ip netns exec "${NAMESPACE}" ip addr add "${DSTIP}"/24 dev "${DSTIF}"
-	ip netns exec "${NAMESPACE}" ip link set "${DSTIF}" up
-
-	ip addr add "${SRCIP}"/24 dev "${SRCIF}"
-	ip link set "${SRCIF}" up
-}
-
-function set_network() {
-	# setup_ns function is coming from lib.sh
-	setup_ns NAMESPACE
-
-	# Create both interfaces, and assign the destination to a different
-	# namespace
-	create_ifaces
-
-	# Link both interfaces back to back
-	link_ifaces
-
-	configure_ip
-}
-
-function create_dynamic_target() {
-	DSTMAC=$(ip netns exec "${NAMESPACE}" \
-		 ip link show "${DSTIF}" | awk '/ether/ {print $2}')
-
-	# Create a dynamic target
-	mkdir "${NETCONS_PATH}"
-
-	echo "${DSTIP}" > "${NETCONS_PATH}"/remote_ip
-	echo "${SRCIP}" > "${NETCONS_PATH}"/local_ip
-	echo "${DSTMAC}" > "${NETCONS_PATH}"/remote_mac
-	echo "${SRCIF}" > "${NETCONS_PATH}"/dev_name
-
-	echo 1 > "${NETCONS_PATH}"/enabled
-}
-
-function cleanup() {
-	local NSIM_DEV_SYS_DEL="/sys/bus/netdevsim/del_device"
-
-	# delete netconsole dynamic reconfiguration
-	echo 0 > "${NETCONS_PATH}"/enabled
-	# Remove key
-	rmdir "${KEY_PATH}"
-	# Remove the configfs entry
-	rmdir "${NETCONS_PATH}"
-
-	# Delete netdevsim devices
-	echo "$NSIM_DEV_2_ID" > "$NSIM_DEV_SYS_DEL"
-	echo "$NSIM_DEV_1_ID" > "$NSIM_DEV_SYS_DEL"
-
-	# this is coming from lib.sh
-	cleanup_all_ns
-
-	# Restoring printk configurations
-	echo "${DEFAULT_PRINTK_VALUES}" > /proc/sys/kernel/printk
-}
-
-function set_user_data() {
-	if [[ ! -d "${NETCONS_PATH}""/userdata" ]]
-	then
-		echo "Userdata path not available in ${NETCONS_PATH}/userdata"
-		exit "${ksft_skip}"
-	fi
-
-	mkdir -p "${KEY_PATH}"
-	VALUE_PATH="${KEY_PATH}""/value"
-	echo "${USERDATA_VALUE}" > "${VALUE_PATH}"
-}
-
-function listen_port_and_save_to() {
-	local OUTPUT=${1}
-	# Just wait for 2 seconds
-	timeout 2 ip netns exec "${NAMESPACE}" \
-		socat UDP-LISTEN:"${PORT}",fork "${OUTPUT}"
-}
-
-function validate_result() {
-	local TMPFILENAME="$1"
-
-	# TMPFILENAME will contain something like:
-	# 6.11.1-0_fbk0_rc13_509_g30d75cea12f7,13,1822,115075213798,-;netconsole selftest: netcons_gtJHM
-	#  key=value
-
-	# Check if the file exists
-	if [ ! -f "$TMPFILENAME" ]; then
-		echo "FAIL: File was not generated." >&2
-		exit "${ksft_fail}"
-	fi
-
-	if ! grep -q "${MSG}" "${TMPFILENAME}"; then
-		echo "FAIL: ${MSG} not found in ${TMPFILENAME}" >&2
-		cat "${TMPFILENAME}" >&2
-		exit "${ksft_fail}"
-	fi
-
-	if ! grep -q "${USERDATA_KEY}=${USERDATA_VALUE}" "${TMPFILENAME}"; then
-		echo "FAIL: ${USERDATA_KEY}=${USERDATA_VALUE} not found in ${TMPFILENAME}" >&2
-		cat "${TMPFILENAME}" >&2
-		exit "${ksft_fail}"
-	fi
-
-	# Delete the file once it is validated, otherwise keep it
-	# for debugging purposes
-	rm "${TMPFILENAME}"
-	exit "${ksft_pass}"
-}
-
-function check_for_dependencies() {
-	if [ "$(id -u)" -ne 0 ]; then
-		echo "This test must be run as root" >&2
-		exit "${ksft_skip}"
-	fi
-
-	if ! which socat > /dev/null ; then
-		echo "SKIP: socat(1) is not available" >&2
-		exit "${ksft_skip}"
-	fi
-
-	if ! which ip > /dev/null ; then
-		echo "SKIP: ip(1) is not available" >&2
-		exit "${ksft_skip}"
-	fi
-
-	if ! which udevadm > /dev/null ; then
-		echo "SKIP: udevadm(1) is not available" >&2
-		exit "${ksft_skip}"
-	fi
-
-	if [ ! -f "${NSIM_DEV_SYS_NEW}" ]; then
-		echo "SKIP: file ${NSIM_DEV_SYS_NEW} does not exist. Check if CONFIG_NETDEVSIM is enabled" >&2
-		exit "${ksft_skip}"
-	fi
-
-	if [ ! -d "${NETCONS_CONFIGFS}" ]; then
-		echo "SKIP: directory ${NETCONS_CONFIGFS} does not exist. Check if NETCONSOLE_DYNAMIC is enabled" >&2
-		exit "${ksft_skip}"
-	fi
-
-	if ip link show "${DSTIF}" 2> /dev/null; then
-		echo "SKIP: interface ${DSTIF} exists in the system. Not overwriting it." >&2
-		exit "${ksft_skip}"
-	fi
-
-	if ip addr list | grep -E "inet.*(${SRCIP}|${DSTIP})" 2> /dev/null; then
-		echo "SKIP: IPs already in use. Skipping it" >&2
-		exit "${ksft_skip}"
-	fi
-}
-
-# ========== #
-# Start here #
-# ========== #
 modprobe netdevsim 2> /dev/null || true
 modprobe netconsole 2> /dev/null || true
 
diff --git a/tools/testing/selftests/drivers/net/netcons_overflow.sh b/tools/testing/selftests/drivers/net/netcons_overflow.sh
new file mode 100755
index 000000000000..29bad56448a2
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/netcons_overflow.sh
@@ -0,0 +1,67 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: GPL-2.0
+
+# This test verifies that users can successfully create up to
+# MAX_USERDATA_ITEMS userdata entries without encountering any failures.
+#
+# Additionally, it tests for expected failure when attempting to exceed this
+# maximum limit.
+#
+# Author: Breno Leitao <leitao@debian.org>
+
+set -euo pipefail
+
+SCRIPTDIR=$(dirname "$(readlink -e "${BASH_SOURCE[0]}")")
+
+source "${SCRIPTDIR}"/lib/sh/lib_netcons.sh
+# This is coming from netconsole code. Check for it in drivers/net/netconsole.c
+MAX_USERDATA_ITEMS=16
+
+# Function to create userdata entries
+function create_userdata_max_entries() {
+	# All these keys should be created without any error
+	for i in $(seq $MAX_USERDATA_ITEMS)
+	do
+		# USERDATA_KEY is used by set_user_data
+		USERDATA_KEY="key"${i}
+		set_user_data
+	done
+}
+
+# Function to verify the entry limit
+function verify_entry_limit() {
+	# Allowing the test to fail without exiting, since the next command
+	# will fail
+	set +e
+	mkdir "${NETCONS_PATH}/userdata/key_that_will_fail" 2> /dev/null
+	ret="$?"
+	set -e
+	if [ "$ret" -eq 0 ];
+	then
+		echo "Adding more than ${MAX_USERDATA_ITEMS} entries in userdata should fail, but it didn't" >&2
+		ls "${NETCONS_PATH}/userdata/" >&2
+		exit "${ksft_fail}"
+	fi
+}
+
+# ========== #
+# Start here #
+# ========== #
+
+modprobe netdevsim 2> /dev/null || true
+modprobe netconsole 2> /dev/null || true
+
+# Check for basic system dependency and exit if not found
+check_for_dependencies
+
+# Remove the namespace, interfaces and netconsole target on exit
+trap cleanup EXIT
+# Create one namespace and two interfaces
+set_network
+# Create a dynamic target for netconsole
+create_dynamic_target
+# populate the maximum number of supported keys in userdata
+create_userdata_max_entries
+# Verify an additional entry is not allowed
+verify_entry_limit
+exit "${ksft_pass}"