x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

When using eBPF to probe CS CALL instructions within a function,
a crash can be triggered.

The eBPF tool probes offset 257 of the __hrtimer_run_queues()
function:

<__hrtimer_run_queues+249>:  nopl   0x0(%rax,%rax,1)
<__hrtimer_run_queues+254>:  mov    %r14,%rdi
<__hrtimer_run_queues+257>:  cs call <__x86_indirect_thunk_r12>
<__hrtimer_run_queues+263>:  mov    %eax,%r12d
<__hrtimer_run_queues+266>:  xchg   %ax,%ax
<__hrtimer_run_queues+268>:  mov    %r13,%rdi

Which triggers this crash:

  BUG: unable to handle page fault for address: 00000000000f41c9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP NOPTI
  CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P
  RIP: 0010:__hrtimer_run_queues+0x106/0x230

Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is
at the 6th byte of the above CS CALL instruction. Since the CS CALL
instruction occupies 6 bytes, the exception occurred in the middle of that
call instruction.

The root cause is that when using eBPF tools to probe in the middle of a
function, a kprobe with INT3 is used as the underlying implementation.

During single-step emulation of the original CALL instruction,
int3_emulate_call() assumes that the probed CALL instruction is 5 bytes
long. However, the actual CS-prefixed CALL instruction occupies 6 bytes,
so it constructs an incorrect exception return address. When the CPU
returns from the kprobe handler, the next instruction to be executed is at
the address of the last byte of that CS CALL instruction. Coincidentally,
starting from that address, the CPU fetches and decodes a completely
different instruction, which ultimately triggers a kernel crash.

Fix the issue by using the actual instruction length obtained from
the instruction decoder when constructing the exception return
address, rather than relying on the hardcoded CALL_INSN_SIZE macro.

[ mingo: Refined the changelog ]

Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

1 files changed, 607 insertions, 0 deletions

diff --git a/drivers/firewire/node-tree-test.c b/drivers/firewire/node-tree-test.c
new file mode 100644
index 000000000..5e6bb5853
--- /dev/null
+++ b/drivers/firewire/node-tree-test.c
@@ -0,0 +1,607 @@
+// SPDX-License-Identifier: GPL-2.0-only
+//
+// node-tree-test.c - An application of Kunit to test node tree.
+//
+// Copyright (c) 2026 Takashi Sakamoto
+//
+// This file can not be built independently since it is intentionally included in core-topology.c.
+
+#include <kunit/test.h>
+#include <kunit/test-bug.h>
+#include <kunit/device.h>
+
+struct private_data {
+	struct fw_card *card;
+	unsigned int release_count;
+};
+
+static int node_tree_test_init(struct kunit *test)
+{
+	struct private_data *data;
+
+	data = kunit_kzalloc(test, sizeof(*data), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, data);
+
+	data->card = kunit_kzalloc(test, sizeof(struct fw_card), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, data->card);
+
+	data->card->device = kunit_device_register(test, "dummy-device");
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, data->card->device);
+
+	test->priv = data;
+
+	return 0;
+}
+
+static void node_tree_test_exit(struct kunit *test)
+{
+	struct private_data *data = test->priv;
+
+	kunit_device_unregister(test, data->card->device);
+	kunit_kfree(test, data->card);
+	kunit_kfree(test, data);
+}
+
+static void release_fw_node(struct fw_card *card, struct fw_node *node, struct fw_node *parent)
+{
+	struct private_data *data = kunit_get_current_test()->priv;
+
+	fw_node_put(node);
+	++data->release_count;
+}
+
+static void node_tree_test_two_nodes(struct kunit *test)
+{
+	//       root
+	// ++============++
+	// ||    phy 1   ||
+	// ||  P0 P1 P2  ||
+	// ++===|==|==|==++
+	//            |
+	//      +-----+
+	//      |
+	// ++===|==x==x==++
+	// ||  P0 P1 P2  ||
+	// ||    phy 0   ||
+	// ++============++
+	//
+	static const u32 self_id_sequence[] = {
+		0x80000080,
+		0x8100005e,
+	};
+	struct private_data *data = test->priv;
+	struct fw_card *card = data->card;
+
+	card->node_id = LOCAL_BUS | 0x01;
+
+	card->local_node = build_tree(card, self_id_sequence, ARRAY_SIZE(self_id_sequence), 123);
+	KUNIT_EXPECT_NOT_NULL(test, card->local_node);
+	KUNIT_EXPECT_PTR_EQ(test, card->local_node, card->root_node);
+
+	struct fw_node *node = card->root_node;
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x01);
+	KUNIT_EXPECT_EQ(test, node->port_count, 3);
+	KUNIT_EXPECT_NULL(test, node->ports[0]);
+	KUNIT_EXPECT_NULL(test, node->ports[1]);
+	KUNIT_EXPECT_NOT_NULL(test, node->ports[2]);
+
+	struct fw_node *parent = node;
+	node = parent->ports[2];
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x00);
+	KUNIT_EXPECT_EQ(test, node->port_count, 1);
+	KUNIT_EXPECT_PTR_EQ(test, node->ports[0], parent);
+
+	++card->color;
+	for_each_fw_node(card, card->root_node, release_fw_node);
+	KUNIT_EXPECT_EQ(test, data->release_count, 2);
+}
+
+static void node_tree_test_two_nodes_1394a(struct kunit *test)
+{
+	//         root
+	// ++===============++
+	// ||      phy 0    ||
+	// ||  P0 P1 P2 P3  ||
+	// ++===|==|==|==|==++
+	//            |
+	//         +--+
+	//         |
+	// ++===|==|==|==|==|==++
+	// ||  P0 P1 P2 P3 P4  ||
+	// ||       phy 1      ||
+	// ++==================++
+	//
+	// NOTE: Just for Self-ID Packets Zero and One.
+	static const u32 self_id_sequence[] = {
+		0x80000065, 0x80814000,
+		0x8100005d, 0x81810000,
+	};
+	struct private_data *data = test->priv;
+	struct fw_card *card = data->card;
+
+	card->node_id = LOCAL_BUS | 0x01;
+
+	card->local_node = build_tree(card, self_id_sequence, ARRAY_SIZE(self_id_sequence), 123);
+	KUNIT_EXPECT_NOT_NULL(test, card->local_node);
+	KUNIT_EXPECT_PTR_EQ(test, card->local_node, card->root_node);
+
+	struct fw_node *node = card->root_node;
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x01);
+	KUNIT_EXPECT_EQ(test, node->port_count, 4);
+	KUNIT_EXPECT_NULL(test, node->ports[0]);
+	KUNIT_EXPECT_NULL(test, node->ports[1]);
+	KUNIT_EXPECT_NOT_NULL(test, node->ports[2]);
+	KUNIT_EXPECT_NULL(test, node->ports[3]);
+
+	struct fw_node *parent = node;
+	node = parent->ports[2];
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x00);
+	KUNIT_EXPECT_EQ(test, node->port_count, 5);
+	KUNIT_EXPECT_NULL(test, node->ports[0]);
+	KUNIT_EXPECT_PTR_EQ(test, node->ports[1], parent);
+	KUNIT_EXPECT_NULL(test, node->ports[2]);
+	KUNIT_EXPECT_NULL(test, node->ports[3]);
+	KUNIT_EXPECT_NULL(test, node->ports[4]);
+
+	++card->color;
+	for_each_fw_node(card, card->root_node, release_fw_node);
+	KUNIT_EXPECT_EQ(test, data->release_count, 2);
+}
+
+static void node_tree_test_three_nodes_case0(struct kunit *test)
+{
+	//       root
+	// ++============++
+	// ||    phy 2   ||
+	// ||  P0 P1 P2  ||
+	// ++===|==|==|==++
+	//      |     |
+	//      +--+  +-----------------+
+	//         |                    |
+	// ++===|==|==x==++  ++===|==|==|==++
+	// ||  P0 P1 P2  ||  ||  P0 P1 P2  ||
+	// ||    phy 0   ||  ||    phy 1   ||
+	// ++============++  ++============++
+	//
+	static const u32 self_id_sequence[] = {
+		0x80000060,
+		0x81000058,
+		0x820000dc,
+	};
+	struct private_data *data = test->priv;
+	struct fw_card *card = data->card;
+
+	card->node_id = LOCAL_BUS | 0x02;
+
+	card->local_node = build_tree(card, self_id_sequence, ARRAY_SIZE(self_id_sequence), 123);
+	KUNIT_EXPECT_NOT_NULL(test, card->local_node);
+	KUNIT_EXPECT_PTR_EQ(test, card->local_node, card->root_node);
+
+	struct fw_node *node = card->root_node;
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x02);
+	KUNIT_EXPECT_EQ(test, node->port_count, 3);
+	KUNIT_EXPECT_NOT_NULL(test, node->ports[0]);
+	KUNIT_EXPECT_NULL(test, node->ports[1]);
+	KUNIT_EXPECT_NOT_NULL(test, node->ports[2]);
+
+	struct fw_node *parent = node;
+	node = parent->ports[0];
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x00);
+	KUNIT_EXPECT_EQ(test, node->port_count, 2);
+	KUNIT_EXPECT_NULL(test, node->ports[0]);
+	KUNIT_EXPECT_PTR_EQ(test, node->ports[1], parent);
+
+	node = parent->ports[2];
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x01);
+	KUNIT_EXPECT_EQ(test, node->port_count, 3);
+	KUNIT_EXPECT_NULL(test, node->ports[0]);
+	KUNIT_EXPECT_NULL(test, node->ports[1]);
+	KUNIT_EXPECT_PTR_EQ(test, node->ports[2], parent);
+
+	++card->color;
+	for_each_fw_node(card, card->root_node, release_fw_node);
+	KUNIT_EXPECT_EQ(test, data->release_count, 3);
+}
+
+static void node_tree_test_three_nodes_case1(struct kunit *test)
+{
+	//       root
+	// ++============++
+	// ||    phy 2   ||
+	// ||  P0 P1 P2  ||
+	// ++===|==|==x==++
+	//         |
+	//         |  +-----------+
+	//         |  |           |
+	// ++===|==|==|==++  ++===|==x==x==++
+	// ||  P0 P1 P2  ||  ||  P0 P1 P2  ||
+	// ||    phy 1   ||  ||    phy 0   ||
+	// ++============++  ++============++
+	//
+	static const u32 self_id_sequence[] = {
+		0x80000080,
+		0x8100006c,
+		0x82000070,
+	};
+	struct private_data *data = test->priv;
+	struct fw_card *card = data->card;
+
+	card->node_id = LOCAL_BUS | 0x02;
+
+	card->local_node = build_tree(card, self_id_sequence, ARRAY_SIZE(self_id_sequence), 123);
+	KUNIT_EXPECT_NOT_NULL(test, card->local_node);
+	KUNIT_EXPECT_PTR_EQ(test, card->local_node, card->root_node);
+
+	struct fw_node *node = card->root_node;
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x02);
+	KUNIT_EXPECT_EQ(test, node->port_count, 2);
+	KUNIT_EXPECT_NULL(test, node->ports[0]);
+	KUNIT_EXPECT_NOT_NULL(test, node->ports[1]);
+
+	struct fw_node *parent = node;
+	node = parent->ports[1];
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x01);
+	KUNIT_EXPECT_EQ(test, node->port_count, 3);
+	KUNIT_EXPECT_NULL(test, node->ports[0]);
+	KUNIT_EXPECT_PTR_EQ(test, node->ports[1], parent);
+	KUNIT_EXPECT_NOT_NULL(test, node->ports[2]);
+
+	parent = node;
+	node = parent->ports[2];
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x00);
+	KUNIT_EXPECT_EQ(test, node->port_count, 1);
+	KUNIT_EXPECT_PTR_EQ(test, node->ports[0], parent);
+
+	++card->color;
+	for_each_fw_node(card, card->root_node, release_fw_node);
+	KUNIT_EXPECT_EQ(test, data->release_count, 3);
+}
+
+static void node_tree_test_four_nodes_case0(struct kunit *test)
+{
+	//       root
+	// ++============++
+	// ||    phy 3   ||
+	// ||  P0 P1 P2  ||
+	// ++===|==|==|==++
+	//         |
+	//         |  +-----------+  +--------------+
+	//         |  |           |  |              |
+	// ++===|==|==|==++  ++===|==|==x==++  ++===|==x==x==++
+	// ||  P0 P1 P2  ||  ||  P0 P1 P2  ||  ||  P0 P1 P2  ||
+	// ||    phy 2   ||  ||    phy 1   ||  ||    phy 0   ||
+	// ++============++  ++============++  ++============++
+	//
+	static const u32 self_id_sequence[] = {
+		0x80000080,
+		0x810000b0,
+		0x8200006c,
+		0x83000074,
+	};
+	struct private_data *data = test->priv;
+	struct fw_card *card = data->card;
+
+	card->node_id = LOCAL_BUS | 0x03;
+
+	card->local_node = build_tree(card, self_id_sequence, ARRAY_SIZE(self_id_sequence), 123);
+	KUNIT_EXPECT_NOT_NULL(test, card->local_node);
+	KUNIT_EXPECT_PTR_EQ(test, card->local_node, card->root_node);
+
+	struct fw_node *node = card->root_node;
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x03);
+	KUNIT_EXPECT_EQ(test, node->port_count, 3);
+	KUNIT_EXPECT_NULL(test, node->ports[0]);
+	KUNIT_EXPECT_NOT_NULL(test, node->ports[1]);
+	KUNIT_EXPECT_NULL(test, node->ports[2]);
+
+	struct fw_node *parent = node;
+	node = parent->ports[1];
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x02);
+	KUNIT_EXPECT_EQ(test, node->port_count, 3);
+	KUNIT_EXPECT_NULL(test, node->ports[0]);
+	KUNIT_EXPECT_PTR_EQ(test, node->ports[1], parent);
+	KUNIT_EXPECT_NOT_NULL(test, node->ports[2]);
+
+	parent = node;
+	node = parent->ports[2];
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x01);
+	KUNIT_EXPECT_EQ(test, node->port_count, 2);
+	KUNIT_EXPECT_PTR_EQ(test, node->ports[0], parent);
+	KUNIT_EXPECT_NOT_NULL(test, node->ports[1]);
+
+	parent = node;
+	node = parent->ports[1];
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x00);
+	KUNIT_EXPECT_EQ(test, node->port_count, 1);
+	KUNIT_EXPECT_PTR_EQ(test, node->ports[0], parent);
+
+	++card->color;
+	for_each_fw_node(card, card->root_node, release_fw_node);
+	KUNIT_EXPECT_EQ(test, data->release_count, 4);
+}
+
+static void node_tree_test_four_nodes_case1(struct kunit *test)
+{
+	//       root
+	// ++============++
+	// ||    phy 3   ||
+	// ||  P0 P1 P2  ||
+	// ++===|==|==x==++
+	//      |
+	//      |  +--------------------------------+
+	//      |  |  +-----------+                 |
+	// ++===|==|==|==++  ++===|==x==x==++  ++===|==|==|==++
+	// ||  P0 P1 P2  ||  ||  P0 P1 P2  ||  ||  P0 P1 P2  ||
+	// ||    phy 2   ||  ||    phy 1   ||  ||    phy 0   ||
+	// ++============++  ++============++  ++============++
+	//
+	static const u32 self_id_sequence[] = {
+		0x80000094,
+		0x81000080,
+		0x820000bc,
+		0x830000d0,
+	};
+	struct private_data *data = test->priv;
+	struct fw_card *card = data->card;
+
+	card->node_id = LOCAL_BUS | 0x03;
+
+	card->local_node = build_tree(card, self_id_sequence, ARRAY_SIZE(self_id_sequence), 123);
+	KUNIT_EXPECT_NOT_NULL(test, card->local_node);
+	KUNIT_EXPECT_PTR_EQ(test, card->local_node, card->root_node);
+
+	struct fw_node *node = card->root_node;
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x03);
+	KUNIT_EXPECT_EQ(test, node->port_count, 2);
+	KUNIT_EXPECT_NOT_NULL(test, node->ports[0]);
+	KUNIT_EXPECT_NULL(test, node->ports[1]);
+
+	struct fw_node *parent = node;
+	node = parent->ports[0];
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x02);
+	KUNIT_EXPECT_EQ(test, node->port_count, 3);
+	KUNIT_EXPECT_PTR_EQ(test, node->ports[0], parent);
+	KUNIT_EXPECT_NOT_NULL(test, node->ports[1]);
+	KUNIT_EXPECT_NOT_NULL(test, node->ports[2]);
+
+	parent = node;
+	node = parent->ports[2];
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x01);
+	KUNIT_EXPECT_EQ(test, node->port_count, 1);
+	KUNIT_EXPECT_PTR_EQ(test, node->ports[0], parent);
+
+	node = parent->ports[1];
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x00);
+	KUNIT_EXPECT_EQ(test, node->port_count, 3);
+	KUNIT_EXPECT_PTR_EQ(test, node->ports[0], parent);
+	KUNIT_EXPECT_NULL(test, node->ports[1]);
+	KUNIT_EXPECT_NULL(test, node->ports[2]);
+
+	++card->color;
+	for_each_fw_node(card, card->root_node, release_fw_node);
+	KUNIT_EXPECT_EQ(test, data->release_count, 4);
+}
+
+static void node_tree_test_four_nodes_case2(struct kunit *test)
+{
+	//       root
+	// ++============++
+	// ||    phy 3   ||
+	// ||  P0 P1 P2  ||
+	// ++===|==|==|==++
+	//      |     |
+	//      |     +-----------------------------+
+	//      |  +--------------+                 |
+	// ++===|==|==x==++  ++===|==|==|==++  ++===|==x==x==++
+	// ||  P0 P1 P2  ||  ||  P0 P1 P2  ||  ||  P0 P1 P2  ||
+	// ||    phy 1   ||  ||    phy 0   ||  ||    phy 2   ||
+	// ++============++  ++============++  ++============++
+	//
+	static const u32 self_id_sequence[] = {
+		0x80000094,
+		0x810000b0,
+		0x82000080,
+		0x830000dc,
+	};
+	struct private_data *data = test->priv;
+	struct fw_card *card = data->card;
+
+	card->node_id = LOCAL_BUS | 0x03;
+
+	card->local_node = build_tree(card, self_id_sequence, ARRAY_SIZE(self_id_sequence), 123);
+	KUNIT_EXPECT_NOT_NULL(test, card->local_node);
+	KUNIT_EXPECT_PTR_EQ(test, card->local_node, card->root_node);
+
+	struct fw_node *node = card->root_node;
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x03);
+	KUNIT_EXPECT_EQ(test, node->port_count, 3);
+	KUNIT_EXPECT_NOT_NULL(test, node->ports[0]);
+	KUNIT_EXPECT_NULL(test, node->ports[1]);
+	KUNIT_EXPECT_NOT_NULL(test, node->ports[2]);
+
+	struct fw_node *parent = node;
+	node = parent->ports[2];
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x02);
+	KUNIT_EXPECT_EQ(test, node->port_count, 1);
+	KUNIT_EXPECT_PTR_EQ(test, node->ports[0], parent);
+
+	node = parent->ports[0];
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x01);
+	KUNIT_EXPECT_EQ(test, node->port_count, 2);
+	KUNIT_EXPECT_PTR_EQ(test, node->ports[0], parent);
+	KUNIT_EXPECT_NOT_NULL(test, node->ports[1]);
+
+	parent = node;
+	node = parent->ports[1];
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x00);
+	KUNIT_EXPECT_EQ(test, node->port_count, 3);
+	KUNIT_EXPECT_PTR_EQ(test, node->ports[0], parent);
+	KUNIT_EXPECT_NULL(test, node->ports[1]);
+	KUNIT_EXPECT_NULL(test, node->ports[2]);
+
+	++card->color;
+	for_each_fw_node(card, card->root_node, release_fw_node);
+	KUNIT_EXPECT_EQ(test, data->release_count, 4);
+}
+
+static void node_tree_test_four_nodes_case3(struct kunit *test)
+{
+	//       root
+	// ++============++
+	// ||    phy 3   ||
+	// ||  P0 P1 P2  ||
+	// ++===|==|==|==++
+	//      |  |  +--------------------------------+
+	//      |  +--------------------+              |
+	//      |                       |              |
+	// ++===|==|==x==++  ++===|==|==|==++  ++===|==|==x==++
+	// ||  P0 P1 P2  ||  ||  P0 P1 P2  ||  ||  P0 P1 P2  ||
+	// ||    phy 0   ||  ||    phy 1   ||  ||    phy 2   ||
+	// ++============++  ++============++  ++============++
+	//
+	static const u32 self_id_sequence[] = {
+		0x80000090,
+		0x81000058,
+		0x82000060,
+		0x830000fc,
+	};
+	struct private_data *data = test->priv;
+	struct fw_card *card = data->card;
+
+	card->node_id = LOCAL_BUS | 0x03;
+
+	card->local_node = build_tree(card, self_id_sequence, ARRAY_SIZE(self_id_sequence), 123);
+	KUNIT_EXPECT_NOT_NULL(test, card->local_node);
+	KUNIT_EXPECT_PTR_EQ(test, card->local_node, card->root_node);
+
+	struct fw_node *node = card->root_node;
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x03);
+	KUNIT_EXPECT_EQ(test, node->port_count, 3);
+	KUNIT_EXPECT_NOT_NULL(test, node->ports[0]);
+	KUNIT_EXPECT_NOT_NULL(test, node->ports[1]);
+	KUNIT_EXPECT_NOT_NULL(test, node->ports[2]);
+
+	struct fw_node *parent = node;
+	node = parent->ports[2];
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x02);
+	KUNIT_EXPECT_EQ(test, node->port_count, 2);
+	KUNIT_EXPECT_NULL(test, node->ports[0]);
+	KUNIT_EXPECT_PTR_EQ(test, node->ports[1], parent);
+
+	node = parent->ports[1];
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x01);
+	KUNIT_EXPECT_EQ(test, node->port_count, 3);
+	KUNIT_EXPECT_NULL(test, node->ports[0]);
+	KUNIT_EXPECT_NULL(test, node->ports[1]);
+	KUNIT_EXPECT_PTR_EQ(test, node->ports[2], parent);
+
+	node = parent->ports[0];
+	KUNIT_EXPECT_EQ(test, node->node_id, LOCAL_BUS | 0x00);
+	KUNIT_EXPECT_EQ(test, node->port_count, 2);
+	KUNIT_EXPECT_PTR_EQ(test, node->ports[0], parent);
+	KUNIT_EXPECT_NULL(test, node->ports[1]);
+
+	++card->color;
+	for_each_fw_node(card, card->root_node, release_fw_node);
+	KUNIT_EXPECT_EQ(test, data->release_count, 4);
+}
+
+static void node_tree_test_invalid_extended_self_id_sequence(struct kunit *test)
+{
+	// Use the same node tree as node_tree_test_four_nodes_case1, except for the invalid
+	// content of self ID packet for the phy 3.
+	static const u32 self_id_sequence[] = {
+		0x80000094,
+		0x81000080,
+		0x820000bc,
+		0x830000d1, // Invalid.
+	};
+	struct private_data *data = test->priv;
+	struct fw_card *card = data->card;
+
+	card->node_id = LOCAL_BUS | 0x03;
+
+	card->local_node = build_tree(card, self_id_sequence, ARRAY_SIZE(self_id_sequence), 123);
+	KUNIT_EXPECT_NULL(test, card->local_node);
+}
+
+static void node_tree_test_invalid_phy_id(struct kunit *test)
+{
+	// Use the same node tree as node_tree_test_four_nodes_case1, except for the invalid
+	// phy ID for phy 3.
+	static const u32 self_id_sequence[] = {
+		0x80000094,
+		0x81000080,
+		0x820000bc,
+		0x8f0000d0, // Invalid.
+	};
+	struct private_data *data = test->priv;
+	struct fw_card *card = data->card;
+
+	card->node_id = LOCAL_BUS | 0x03;
+
+	card->local_node = build_tree(card, self_id_sequence, ARRAY_SIZE(self_id_sequence), 123);
+	KUNIT_EXPECT_NULL(test, card->local_node);
+}
+
+static void node_tree_test_invalid_child_port_count(struct kunit *test)
+{
+	// Use the same node tree as node_tree_test_four_nodes_case1, except for the invalid
+	// count of child ports for phy 3.
+	static const u32 self_id_sequence[] = {
+		0x80000094,
+		0x81000080,
+		0x820000bc,
+		0x830000fc, // Invalid.
+	};
+	struct private_data *data = test->priv;
+	struct fw_card *card = data->card;
+
+	card->node_id = LOCAL_BUS | 0x03;
+
+	card->local_node = build_tree(card, self_id_sequence, ARRAY_SIZE(self_id_sequence), 123);
+	KUNIT_EXPECT_NULL(test, card->local_node);
+}
+
+static void node_tree_test_invalid_parent_port_count(struct kunit *test)
+{
+	// Use the same node tree as node_tree_test_four_nodes_case1, except for the invalid
+	// count of parent ports for phy 3.
+	static const u32 self_id_sequence[] = {
+		0x80000094,
+		0x81000080,
+		0x820000bc,
+		0x830000e8, // Invalid.
+	};
+	struct private_data *data = test->priv;
+	struct fw_card *card = data->card;
+
+	card->node_id = LOCAL_BUS | 0x03;
+
+	card->local_node = build_tree(card, self_id_sequence, ARRAY_SIZE(self_id_sequence), 123);
+	KUNIT_EXPECT_NULL(test, card->local_node);
+}
+
+static struct kunit_case node_tree_test_cases[] = {
+	KUNIT_CASE(node_tree_test_two_nodes),
+	KUNIT_CASE(node_tree_test_two_nodes_1394a),
+	KUNIT_CASE(node_tree_test_three_nodes_case0),
+	KUNIT_CASE(node_tree_test_three_nodes_case1),
+	KUNIT_CASE(node_tree_test_four_nodes_case0),
+	KUNIT_CASE(node_tree_test_four_nodes_case1),
+	KUNIT_CASE(node_tree_test_four_nodes_case2),
+	KUNIT_CASE(node_tree_test_four_nodes_case3),
+	KUNIT_CASE(node_tree_test_invalid_extended_self_id_sequence),
+	KUNIT_CASE(node_tree_test_invalid_phy_id),
+	KUNIT_CASE(node_tree_test_invalid_child_port_count),
+	KUNIT_CASE(node_tree_test_invalid_parent_port_count),
+	{}
+};
+
+static struct kunit_suite node_tree_test_suite = {
+	.name = "firewire-node-tree",
+	.init = node_tree_test_init,
+	.exit = node_tree_test_exit,
+	.test_cases = node_tree_test_cases,
+};
+kunit_test_suite(node_tree_test_suite);