[PATCH blktests v2] nvme/071: add a test for fcloop LS request use-after-free

[Nguyen Ngoc Thang <ngocthang2710.1999@gmail.com>]

Delete the fcloop remote port and then the target port while an
association is being deleted. The Disconnect Association LS is completed
from a work item that can run after nvmet_fc_unregister_targetport() freed
the pending request, which KASAN reports as a use-after-free in
fcloop_tport_lsrqst_work().

Kernel fix: "nvmet-fc: flush nvmet_wq twice on targetport unregister"

Signed-off-by: Nguyen Ngoc Thang <ngocthang2710.1999@gmail.com>
---
Changes in v2 (thanks Shin'ichiro for the review):
- Note the kernel fix's commit title in the file header.
- local -a ports, and use _get_fc_host_port() instead of reading
  ports_to_hosts directly.
- Connect with --ctrl-loss-tmo 0. Without it, the host can spend up to
  NVMF_DEF_CTRL_LOSS_TMO (600s) retrying reconnect after we pull the
  remote port, which is likely the hang you saw; disconnecting it
  cleanly then has to wait on that reconnect state first.
- Drop the swept delay before pulling the ports. I could not tell it
  apart from a fixed "sleep 0" here either (KASAN UAF + list_debug BUG,
  both with and without it), so it wasn't earning its complexity.
- v1: https://lore.kernel.org/linux-block/20260921145659.17151-1-ngocthang2710.1999@gmail.com/

 tests/nvme/071     | 75 ++++++++++++++++++++++++++++++++++++++++++++++
 tests/nvme/071.out |  2 ++
 2 files changed, 77 insertions(+)
 create mode 100755 tests/nvme/071
 create mode 100644 tests/nvme/071.out

diff --git a/tests/nvme/071 b/tests/nvme/071
new file mode 100755
index 0000000..406a841
--- /dev/null
+++ b/tests/nvme/071
@@ -0,0 +1,75 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-3.0+
+# Copyright (C) 2026 Nguyen Ngoc Thang
+#
+# Regression test for a use-after-free in fcloop when the target port is
+# deleted right after the remote port. Deleting the association sends a
+# Disconnect Association LS whose completion is queued while
+# nvmet_fc_unregister_targetport() is flushing nvmet_wq. The pending LS request
+# was freed before that completion ran.
+#
+# Kernel fix: "nvmet-fc: flush nvmet_wq twice on targetport unregister"
+
+. tests/nvme/rc
+
+DESCRIPTION="delete fcloop target port right after remote port"
+QUICK=1
+
+requires() {
+	_nvme_requires
+	_have_loop
+	_require_nvme_trtype fc
+}
+
+set_conditions() {
+	_set_nvme_trtype "$@"
+}
+
+test() {
+	echo "Running ${TEST_NAME}"
+
+	_setup_nvmet
+
+	local -a ports
+	local i port host_port
+
+	_nvmet_target_setup
+
+	_get_nvmet_ports "${def_subsysnqn}" ports
+	port="${ports[0]}"
+	host_port="$(_get_fc_host_port "${port}")"
+
+	for ((i = 0; i < 20; i++)); do
+		# ctrl-loss-tmo=0 so the host drops the controller on the first
+		# failed reconnect instead of retrying for NVMF_DEF_CTRL_LOSS_TMO
+		# (600s), which would make each iteration look like it hangs.
+		_nvme_connect_subsys --ctrl-loss-tmo 0
+		sleep 0.05
+
+		# Deleting the association sends a Disconnect Association LS.
+		_remove_nvmet_subsystem_from_port "${port}" "${def_subsysnqn}"
+
+		# Remote port first, so the LS can't reach the host anymore.
+		_nvme_fcloop_del_rport "$(_host_wwnn "${host_port}")" \
+				       "$(_host_wwpn "${host_port}")" \
+				       "$(_remote_wwnn "${port}")" \
+				       "$(_remote_wwpn "${port}")"
+		_nvme_fcloop_del_tport "$(_remote_wwnn "${port}")" \
+				       "$(_remote_wwpn "${port}")"
+
+		# The host keeps trying to reconnect, drop the controller.
+		_nvme_disconnect_subsys >> "${FULL}" 2>&1
+
+		_nvme_fcloop_add_tport "$(_remote_wwnn "${port}")" \
+				       "$(_remote_wwpn "${port}")"
+		_nvme_fcloop_add_rport "$(_host_wwnn "${host_port}")" \
+				       "$(_host_wwpn "${host_port}")" \
+				       "$(_remote_wwnn "${port}")" \
+				       "$(_remote_wwpn "${port}")"
+		_add_nvmet_subsys_to_port "${port}" "${def_subsysnqn}"
+	done
+
+	_nvmet_target_cleanup
+
+	echo "Test complete"
+}
diff --git a/tests/nvme/071.out b/tests/nvme/071.out
new file mode 100644
index 0000000..146809b
--- /dev/null
+++ b/tests/nvme/071.out
@@ -0,0 +1,2 @@
+Running nvme/071
+Test complete
-- 
2.43.0