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, 256 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/zet6223.c b/drivers/input/touchscreen/zet6223.c
new file mode 100644
index 000000000..a341142f3
--- /dev/null
+++ b/drivers/input/touchscreen/zet6223.c
@@ -0,0 +1,256 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2016, Jelle van der Waa <jelle@vdwaa.nl>
+ */
+
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/input/mt.h>
+#include <linux/input/touchscreen.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+#include <linux/unaligned.h>
+
+#define ZET6223_MAX_FINGERS		16
+#define ZET6223_MAX_PKT_SIZE		(3 + 4 * ZET6223_MAX_FINGERS)
+
+#define ZET6223_CMD_INFO		0xB2
+#define ZET6223_CMD_INFO_LENGTH		17
+#define ZET6223_VALID_PACKET		0x3c
+
+#define ZET6223_POWER_ON_DELAY_MSEC	30
+
+struct zet6223_ts {
+	struct i2c_client *client;
+	struct input_dev *input;
+	struct touchscreen_properties prop;
+	struct regulator_bulk_data supplies[2];
+	u16 max_x;
+	u16 max_y;
+	u8 fingernum;
+};
+
+static int zet6223_start(struct input_dev *dev)
+{
+	struct zet6223_ts *ts = input_get_drvdata(dev);
+
+	enable_irq(ts->client->irq);
+
+	return 0;
+}
+
+static void zet6223_stop(struct input_dev *dev)
+{
+	struct zet6223_ts *ts = input_get_drvdata(dev);
+
+	disable_irq(ts->client->irq);
+}
+
+static irqreturn_t zet6223_irq(int irq, void *dev_id)
+{
+	struct zet6223_ts *ts = dev_id;
+	u16 finger_bits;
+
+	/*
+	 * First 3 bytes are an identifier, two bytes of finger data.
+	 * X, Y data per finger is 4 bytes.
+	 */
+	u8 bufsize = 3 + 4 * ts->fingernum;
+	u8 buf[ZET6223_MAX_PKT_SIZE];
+	int i;
+	int ret;
+	int error;
+
+	ret = i2c_master_recv(ts->client, buf, bufsize);
+	if (ret != bufsize) {
+		error = ret < 0 ? ret : -EIO;
+		dev_err_ratelimited(&ts->client->dev,
+				    "Error reading input data: %d\n", error);
+		return IRQ_HANDLED;
+	}
+
+	if (buf[0] != ZET6223_VALID_PACKET)
+		return IRQ_HANDLED;
+
+	finger_bits = get_unaligned_be16(buf + 1);
+	for (i = 0; i < ts->fingernum; i++) {
+		if (!(finger_bits & BIT(15 - i)))
+			continue;
+
+		input_mt_slot(ts->input, i);
+		input_mt_report_slot_state(ts->input, MT_TOOL_FINGER, true);
+		input_event(ts->input, EV_ABS, ABS_MT_POSITION_X,
+				((buf[i + 3] >> 4) << 8) + buf[i + 4]);
+		input_event(ts->input, EV_ABS, ABS_MT_POSITION_Y,
+				((buf[i + 3] & 0xF) << 8) + buf[i + 5]);
+	}
+
+	input_mt_sync_frame(ts->input);
+	input_sync(ts->input);
+
+	return IRQ_HANDLED;
+}
+
+static void zet6223_power_off(void *_ts)
+{
+	struct zet6223_ts *ts = _ts;
+
+	regulator_bulk_disable(ARRAY_SIZE(ts->supplies), ts->supplies);
+}
+
+static int zet6223_power_on(struct zet6223_ts *ts)
+{
+	struct device *dev = &ts->client->dev;
+	int error;
+
+	ts->supplies[0].supply = "vio";
+	ts->supplies[1].supply = "vcc";
+
+	error = devm_regulator_bulk_get(dev, ARRAY_SIZE(ts->supplies),
+					ts->supplies);
+	if (error)
+		return error;
+
+	error = regulator_bulk_enable(ARRAY_SIZE(ts->supplies), ts->supplies);
+	if (error)
+		return error;
+
+	msleep(ZET6223_POWER_ON_DELAY_MSEC);
+
+	error = devm_add_action_or_reset(dev, zet6223_power_off, ts);
+	if (error) {
+		dev_err(dev, "failed to install poweroff action: %d\n", error);
+		return error;
+	}
+
+	return 0;
+}
+
+static int zet6223_query_device(struct zet6223_ts *ts)
+{
+	u8 buf[ZET6223_CMD_INFO_LENGTH];
+	u8 cmd = ZET6223_CMD_INFO;
+	int ret;
+	int error;
+
+	ret = i2c_master_send(ts->client, &cmd, sizeof(cmd));
+	if (ret != sizeof(cmd)) {
+		error = ret < 0 ? ret : -EIO;
+		dev_err(&ts->client->dev,
+			"touchpanel info cmd failed: %d\n", error);
+		return error;
+	}
+
+	ret = i2c_master_recv(ts->client, buf, sizeof(buf));
+	if (ret != sizeof(buf)) {
+		error = ret < 0 ? ret : -EIO;
+		dev_err(&ts->client->dev,
+			"failed to retrieve touchpanel info: %d\n", error);
+		return error;
+	}
+
+	ts->fingernum = buf[15] & 0x7F;
+	if (ts->fingernum > ZET6223_MAX_FINGERS) {
+		dev_warn(&ts->client->dev,
+			 "touchpanel reports %d fingers, limiting to %d\n",
+			 ts->fingernum, ZET6223_MAX_FINGERS);
+		ts->fingernum = ZET6223_MAX_FINGERS;
+	}
+
+	ts->max_x = get_unaligned_le16(&buf[8]);
+	ts->max_y = get_unaligned_le16(&buf[10]);
+
+	return 0;
+}
+
+static int zet6223_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct zet6223_ts *ts;
+	struct input_dev *input;
+	int error;
+
+	if (!client->irq) {
+		dev_err(dev, "no irq specified\n");
+		return -EINVAL;
+	}
+
+	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
+	if (!ts)
+		return -ENOMEM;
+
+	ts->client = client;
+
+	error = zet6223_power_on(ts);
+	if (error)
+		return error;
+
+	error = zet6223_query_device(ts);
+	if (error)
+		return error;
+
+	ts->input = input = devm_input_allocate_device(dev);
+	if (!input)
+		return -ENOMEM;
+
+	input_set_drvdata(input, ts);
+
+	input->name = client->name;
+	input->id.bustype = BUS_I2C;
+	input->open = zet6223_start;
+	input->close = zet6223_stop;
+
+	input_set_abs_params(input, ABS_MT_POSITION_X, 0, ts->max_x, 0, 0);
+	input_set_abs_params(input, ABS_MT_POSITION_Y, 0, ts->max_y, 0, 0);
+
+	touchscreen_parse_properties(input, true, &ts->prop);
+
+	error = input_mt_init_slots(input, ts->fingernum,
+				    INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
+	if (error)
+		return error;
+
+	error = devm_request_threaded_irq(dev, client->irq, NULL, zet6223_irq,
+					  IRQF_ONESHOT, client->name, ts);
+	if (error) {
+		dev_err(dev, "failed to request irq %d: %d\n",
+			client->irq, error);
+		return error;
+	}
+
+	zet6223_stop(input);
+
+	error = input_register_device(input);
+	if (error)
+		return error;
+
+	return 0;
+}
+
+static const struct of_device_id zet6223_of_match[] = {
+	{ .compatible = "zeitec,zet6223" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, zet6223_of_match);
+
+static const struct i2c_device_id zet6223_id[] = {
+	{ .name = "zet6223" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, zet6223_id);
+
+static struct i2c_driver zet6223_driver = {
+	.driver = {
+		.name = "zet6223",
+		.of_match_table = zet6223_of_match,
+	},
+	.probe = zet6223_probe,
+	.id_table = zet6223_id
+};
+module_i2c_driver(zet6223_driver);
+
+MODULE_AUTHOR("Jelle van der Waa <jelle@vdwaa.nl>");
+MODULE_DESCRIPTION("ZEITEC zet622x I2C touchscreen driver");
+MODULE_LICENSE("GPL");