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, 263 insertions, 0 deletions

diff --git a/drivers/input/keyboard/qt1070.c b/drivers/input/keyboard/qt1070.c
new file mode 100644
index 000000000..e31cb115a
--- /dev/null
+++ b/drivers/input/keyboard/qt1070.c
@@ -0,0 +1,263 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Atmel AT42QT1070 QTouch Sensor Controller
+ *
+ *  Copyright (C) 2011 Atmel
+ *
+ *  Authors: Bo Shen <voice.shen@atmel.com>
+ *
+ *  Base on AT42QT2160 driver by:
+ *  Raphael Derosso Pereira <raphaelpereira@gmail.com>
+ *  Copyright (C) 2009
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/slab.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+#include <linux/jiffies.h>
+#include <linux/delay.h>
+
+/* Address for each register */
+#define CHIP_ID            0x00
+#define QT1070_CHIP_ID     0x2E
+
+#define FW_VERSION         0x01
+#define QT1070_FW_VERSION  0x15
+
+#define DET_STATUS         0x02
+
+#define KEY_STATUS         0x03
+
+/* Calibrate */
+#define CALIBRATE_CMD      0x38
+#define QT1070_CAL_TIME    200
+
+/* Reset */
+#define RESET              0x39
+#define QT1070_RESET_TIME  255
+
+/* AT42QT1070 support up to 7 keys */
+static const unsigned short qt1070_key2code[] = {
+	KEY_0, KEY_1, KEY_2, KEY_3,
+	KEY_4, KEY_5, KEY_6,
+};
+
+struct qt1070_data {
+	struct i2c_client *client;
+	struct input_dev *input;
+	unsigned int irq;
+	unsigned short keycodes[ARRAY_SIZE(qt1070_key2code)];
+	u8 last_keys;
+};
+
+static int qt1070_read(struct i2c_client *client, u8 reg)
+{
+	int ret;
+
+	ret = i2c_smbus_read_byte_data(client, reg);
+	if (ret < 0)
+		dev_err(&client->dev,
+			"can not read register, returned %d\n", ret);
+
+	return ret;
+}
+
+static int qt1070_write(struct i2c_client *client, u8 reg, u8 data)
+{
+	int ret;
+
+	ret = i2c_smbus_write_byte_data(client, reg, data);
+	if (ret < 0)
+		dev_err(&client->dev,
+			"can not write register, returned %d\n", ret);
+
+	return ret;
+}
+
+static bool qt1070_identify(struct i2c_client *client)
+{
+	int id, ver;
+
+	/* Read Chip ID */
+	id = qt1070_read(client, CHIP_ID);
+	if (id != QT1070_CHIP_ID) {
+		dev_err(&client->dev, "ID %d not supported\n", id);
+		return false;
+	}
+
+	/* Read firmware version */
+	ver = qt1070_read(client, FW_VERSION);
+	if (ver < 0) {
+		dev_err(&client->dev, "could not read the firmware version\n");
+		return false;
+	}
+
+	dev_info(&client->dev, "AT42QT1070 firmware version %x\n", ver);
+
+	return true;
+}
+
+static irqreturn_t qt1070_interrupt(int irq, void *dev_id)
+{
+	struct qt1070_data *data = dev_id;
+	struct i2c_client *client = data->client;
+	struct input_dev *input = data->input;
+	int i;
+	u8 new_keys, keyval, mask = 0x01;
+
+	/* Read the detected status register, thus clearing interrupt */
+	qt1070_read(client, DET_STATUS);
+
+	/* Read which key changed */
+	new_keys = qt1070_read(client, KEY_STATUS);
+
+	for (i = 0; i < ARRAY_SIZE(qt1070_key2code); i++) {
+		keyval = new_keys & mask;
+		if ((data->last_keys & mask) != keyval)
+			input_report_key(input, data->keycodes[i], keyval);
+		mask <<= 1;
+	}
+	input_sync(input);
+
+	data->last_keys = new_keys;
+	return IRQ_HANDLED;
+}
+
+static int qt1070_probe(struct i2c_client *client)
+{
+	struct qt1070_data *data;
+	struct input_dev *input;
+	int i;
+	int err;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE)) {
+		dev_err(&client->dev, "%s adapter not supported\n",
+			dev_driver_string(&client->adapter->dev));
+		return -ENODEV;
+	}
+
+	if (!client->irq) {
+		dev_err(&client->dev, "please assign the irq to this device\n");
+		return -EINVAL;
+	}
+
+	/* Identify the qt1070 chip */
+	if (!qt1070_identify(client))
+		return -ENODEV;
+
+	data = devm_kzalloc(&client->dev, sizeof(struct qt1070_data),
+			    GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	input = devm_input_allocate_device(&client->dev);
+	if (!input)
+		return -ENOMEM;
+
+	data->client = client;
+	data->input = input;
+	data->irq = client->irq;
+
+	input->name = "AT42QT1070 QTouch Sensor";
+	input->id.bustype = BUS_I2C;
+
+	/* Add the keycode */
+	input->keycode = data->keycodes;
+	input->keycodesize = sizeof(data->keycodes[0]);
+	input->keycodemax = ARRAY_SIZE(qt1070_key2code);
+
+	__set_bit(EV_KEY, input->evbit);
+
+	for (i = 0; i < ARRAY_SIZE(qt1070_key2code); i++) {
+		data->keycodes[i] = qt1070_key2code[i];
+		__set_bit(qt1070_key2code[i], input->keybit);
+	}
+
+	/* Calibrate device */
+	qt1070_write(client, CALIBRATE_CMD, 1);
+	msleep(QT1070_CAL_TIME);
+
+	/* Soft reset */
+	qt1070_write(client, RESET, 1);
+	msleep(QT1070_RESET_TIME);
+
+	err = devm_request_threaded_irq(&client->dev, client->irq,
+					NULL, qt1070_interrupt,
+					IRQF_TRIGGER_NONE | IRQF_ONESHOT,
+					client->dev.driver->name, data);
+	if (err) {
+		dev_err(&client->dev, "fail to request irq\n");
+		return err;
+	}
+
+	/* Register the input device */
+	err = input_register_device(data->input);
+	if (err) {
+		dev_err(&client->dev, "Failed to register input device\n");
+		return err;
+	}
+
+	i2c_set_clientdata(client, data);
+
+	/* Read to clear the chang line */
+	qt1070_read(client, DET_STATUS);
+
+	return 0;
+}
+
+static int qt1070_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct qt1070_data *data = i2c_get_clientdata(client);
+
+	if (device_may_wakeup(dev))
+		enable_irq_wake(data->irq);
+
+	return 0;
+}
+
+static int qt1070_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct qt1070_data *data = i2c_get_clientdata(client);
+
+	if (device_may_wakeup(dev))
+		disable_irq_wake(data->irq);
+
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(qt1070_pm_ops, qt1070_suspend, qt1070_resume);
+
+static const struct i2c_device_id qt1070_id[] = {
+	{ .name = "qt1070" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, qt1070_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id qt1070_of_match[] = {
+	{ .compatible = "qt1070", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, qt1070_of_match);
+#endif
+
+static struct i2c_driver qt1070_driver = {
+	.driver	= {
+		.name	= "qt1070",
+		.of_match_table = of_match_ptr(qt1070_of_match),
+		.pm	= pm_sleep_ptr(&qt1070_pm_ops),
+	},
+	.id_table	= qt1070_id,
+	.probe		= qt1070_probe,
+};
+
+module_i2c_driver(qt1070_driver);
+
+MODULE_AUTHOR("Bo Shen <voice.shen@atmel.com>");
+MODULE_DESCRIPTION("Driver for AT42QT1070 QTouch sensor");
+MODULE_LICENSE("GPL");