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, 439 insertions, 0 deletions

diff --git a/drivers/hwmon/max31730.c b/drivers/hwmon/max31730.c
new file mode 100644
index 000000000..d132be2d6
--- /dev/null
+++ b/drivers/hwmon/max31730.c
@@ -0,0 +1,439 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Driver for MAX31730 3-Channel Remote Temperature Sensor
+ *
+ * Copyright (c) 2019 Guenter Roeck <linux@roeck-us.net>
+ */
+
+#include <linux/bits.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/hwmon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+
+/* Addresses scanned */
+static const unsigned short normal_i2c[] = { 0x1c, 0x1d, 0x1e, 0x1f, 0x4c,
+					     0x4d, 0x4e, 0x4f, I2C_CLIENT_END };
+
+/* The MAX31730 registers */
+#define MAX31730_REG_TEMP		0x00
+#define MAX31730_REG_CONF		0x13
+#define  MAX31730_STOP			BIT(7)
+#define  MAX31730_EXTRANGE		BIT(1)
+#define MAX31730_REG_TEMP_OFFSET	0x16
+#define  MAX31730_TEMP_OFFSET_BASELINE	0x77
+#define MAX31730_REG_OFFSET_ENABLE	0x17
+#define MAX31730_REG_TEMP_MAX		0x20
+#define MAX31730_REG_TEMP_MIN		0x30
+#define MAX31730_REG_STATUS_HIGH	0x32
+#define MAX31730_REG_STATUS_LOW		0x33
+#define MAX31730_REG_CHANNEL_ENABLE	0x35
+#define MAX31730_REG_TEMP_FAULT		0x36
+
+#define MAX31730_REG_MFG_ID		0x50
+#define  MAX31730_MFG_ID		0x4d
+#define MAX31730_REG_MFG_REV		0x51
+#define  MAX31730_MFG_REV		0x01
+
+#define MAX31730_TEMP_MIN		(-128000)
+#define MAX31730_TEMP_MAX		127937
+
+/* Each client has this additional data */
+struct max31730_data {
+	struct i2c_client	*client;
+	u8			orig_conf;
+	u8			current_conf;
+	u8			offset_enable;
+	u8			channel_enable;
+};
+
+/*-----------------------------------------------------------------------*/
+
+static inline long max31730_reg_to_mc(s16 temp)
+{
+	return DIV_ROUND_CLOSEST((temp >> 4) * 1000, 16);
+}
+
+static int max31730_write_config(struct max31730_data *data, u8 set_mask,
+				 u8 clr_mask)
+{
+	u8 value;
+
+	clr_mask |= MAX31730_EXTRANGE;
+	value = data->current_conf & ~clr_mask;
+	value |= set_mask;
+
+	if (data->current_conf != value) {
+		s32 err;
+
+		err = i2c_smbus_write_byte_data(data->client, MAX31730_REG_CONF,
+						value);
+		if (err)
+			return err;
+		data->current_conf = value;
+	}
+	return 0;
+}
+
+static int max31730_set_enable(struct i2c_client *client, int reg,
+			       u8 *confdata, int channel, bool enable)
+{
+	u8 regval = *confdata;
+	int err;
+
+	if (enable)
+		regval |= BIT(channel);
+	else
+		regval &= ~BIT(channel);
+
+	if (regval != *confdata) {
+		err = i2c_smbus_write_byte_data(client, reg, regval);
+		if (err)
+			return err;
+		*confdata = regval;
+	}
+	return 0;
+}
+
+static int max31730_set_offset_enable(struct max31730_data *data, int channel,
+				      bool enable)
+{
+	return max31730_set_enable(data->client, MAX31730_REG_OFFSET_ENABLE,
+				   &data->offset_enable, channel, enable);
+}
+
+static int max31730_set_channel_enable(struct max31730_data *data, int channel,
+				       bool enable)
+{
+	return max31730_set_enable(data->client, MAX31730_REG_CHANNEL_ENABLE,
+				   &data->channel_enable, channel, enable);
+}
+
+static int max31730_read(struct device *dev, enum hwmon_sensor_types type,
+			 u32 attr, int channel, long *val)
+{
+	struct max31730_data *data = dev_get_drvdata(dev);
+	int regval, reg, offset;
+
+	if (type != hwmon_temp)
+		return -EINVAL;
+
+	switch (attr) {
+	case hwmon_temp_input:
+		if (!(data->channel_enable & BIT(channel)))
+			return -ENODATA;
+		reg = MAX31730_REG_TEMP + (channel * 2);
+		break;
+	case hwmon_temp_max:
+		reg = MAX31730_REG_TEMP_MAX + (channel * 2);
+		break;
+	case hwmon_temp_min:
+		reg = MAX31730_REG_TEMP_MIN;
+		break;
+	case hwmon_temp_enable:
+		*val = !!(data->channel_enable & BIT(channel));
+		return 0;
+	case hwmon_temp_offset:
+		if (!channel)
+			return -EINVAL;
+		if (!(data->offset_enable & BIT(channel))) {
+			*val = 0;
+			return 0;
+		}
+		offset = i2c_smbus_read_byte_data(data->client,
+						  MAX31730_REG_TEMP_OFFSET);
+		if (offset < 0)
+			return offset;
+		*val = (offset - MAX31730_TEMP_OFFSET_BASELINE) * 125;
+		return 0;
+	case hwmon_temp_fault:
+		regval = i2c_smbus_read_byte_data(data->client,
+						  MAX31730_REG_TEMP_FAULT);
+		if (regval < 0)
+			return regval;
+		*val = !!(regval & BIT(channel));
+		return 0;
+	case hwmon_temp_min_alarm:
+		regval = i2c_smbus_read_byte_data(data->client,
+						  MAX31730_REG_STATUS_LOW);
+		if (regval < 0)
+			return regval;
+		*val = !!(regval & BIT(channel));
+		return 0;
+	case hwmon_temp_max_alarm:
+		regval = i2c_smbus_read_byte_data(data->client,
+						  MAX31730_REG_STATUS_HIGH);
+		if (regval < 0)
+			return regval;
+		*val = !!(regval & BIT(channel));
+		return 0;
+	default:
+		return -EINVAL;
+	}
+	regval = i2c_smbus_read_word_swapped(data->client, reg);
+	if (regval < 0)
+		return regval;
+
+	*val = max31730_reg_to_mc(regval);
+
+	return 0;
+}
+
+static int max31730_write(struct device *dev, enum hwmon_sensor_types type,
+			  u32 attr, int channel, long val)
+{
+	struct max31730_data *data = dev_get_drvdata(dev);
+	int reg, err;
+
+	if (type != hwmon_temp)
+		return -EINVAL;
+
+	switch (attr) {
+	case hwmon_temp_max:
+		reg = MAX31730_REG_TEMP_MAX + channel * 2;
+		break;
+	case hwmon_temp_min:
+		reg = MAX31730_REG_TEMP_MIN;
+		break;
+	case hwmon_temp_enable:
+		if (val != 0 && val != 1)
+			return -EINVAL;
+		return max31730_set_channel_enable(data, channel, val);
+	case hwmon_temp_offset:
+		val = clamp_val(val, -14875, 17000) + 14875;
+		val = DIV_ROUND_CLOSEST(val, 125);
+		err = max31730_set_offset_enable(data, channel,
+					val != MAX31730_TEMP_OFFSET_BASELINE);
+		if (err)
+			return err;
+		return i2c_smbus_write_byte_data(data->client,
+						 MAX31730_REG_TEMP_OFFSET, val);
+	default:
+		return -EINVAL;
+	}
+
+	val = clamp_val(val, MAX31730_TEMP_MIN, MAX31730_TEMP_MAX);
+	val = DIV_ROUND_CLOSEST(val << 4, 1000) << 4;
+
+	return i2c_smbus_write_word_swapped(data->client, reg, (u16)val);
+}
+
+static umode_t max31730_is_visible(const void *data,
+				   enum hwmon_sensor_types type,
+				   u32 attr, int channel)
+{
+	switch (type) {
+	case hwmon_temp:
+		switch (attr) {
+		case hwmon_temp_input:
+		case hwmon_temp_min_alarm:
+		case hwmon_temp_max_alarm:
+		case hwmon_temp_fault:
+			return 0444;
+		case hwmon_temp_min:
+			return channel ? 0444 : 0644;
+		case hwmon_temp_offset:
+		case hwmon_temp_enable:
+		case hwmon_temp_max:
+			return 0644;
+		}
+		break;
+	default:
+		break;
+	}
+	return 0;
+}
+
+static const struct hwmon_channel_info * const max31730_info[] = {
+	HWMON_CHANNEL_INFO(chip,
+			   HWMON_C_REGISTER_TZ),
+	HWMON_CHANNEL_INFO(temp,
+			   HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
+			   HWMON_T_ENABLE |
+			   HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM,
+			   HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
+			   HWMON_T_OFFSET | HWMON_T_ENABLE |
+			   HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM |
+			   HWMON_T_FAULT,
+			   HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
+			   HWMON_T_OFFSET | HWMON_T_ENABLE |
+			   HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM |
+			   HWMON_T_FAULT,
+			   HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
+			   HWMON_T_OFFSET | HWMON_T_ENABLE |
+			   HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM |
+			   HWMON_T_FAULT
+			   ),
+	NULL
+};
+
+static const struct hwmon_ops max31730_hwmon_ops = {
+	.is_visible = max31730_is_visible,
+	.read = max31730_read,
+	.write = max31730_write,
+};
+
+static const struct hwmon_chip_info max31730_chip_info = {
+	.ops = &max31730_hwmon_ops,
+	.info = max31730_info,
+};
+
+static void max31730_remove(void *data)
+{
+	struct max31730_data *max31730 = data;
+	struct i2c_client *client = max31730->client;
+
+	i2c_smbus_write_byte_data(client, MAX31730_REG_CONF,
+				  max31730->orig_conf);
+}
+
+static int
+max31730_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct device *hwmon_dev;
+	struct max31730_data *data;
+	int status, err;
+
+	if (!i2c_check_functionality(client->adapter,
+			I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA))
+		return -EIO;
+
+	data = devm_kzalloc(dev, sizeof(struct max31730_data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->client = client;
+
+	/* Cache original configuration and enable status */
+	status = i2c_smbus_read_byte_data(client, MAX31730_REG_CHANNEL_ENABLE);
+	if (status < 0)
+		return status;
+	data->channel_enable = status;
+
+	status = i2c_smbus_read_byte_data(client, MAX31730_REG_OFFSET_ENABLE);
+	if (status < 0)
+		return status;
+	data->offset_enable = status;
+
+	status = i2c_smbus_read_byte_data(client, MAX31730_REG_CONF);
+	if (status < 0)
+		return status;
+	data->orig_conf = status;
+	data->current_conf = status;
+
+	err = max31730_write_config(data,
+				    data->channel_enable ? 0 : MAX31730_STOP,
+				    data->channel_enable ? MAX31730_STOP : 0);
+	if (err)
+		return err;
+
+	dev_set_drvdata(dev, data);
+
+	err = devm_add_action_or_reset(dev, max31730_remove, data);
+	if (err)
+		return err;
+
+	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
+							 data,
+							 &max31730_chip_info,
+							 NULL);
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct i2c_device_id max31730_ids[] = {
+	{ .name = "max31730" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, max31730_ids);
+
+static const struct of_device_id __maybe_unused max31730_of_match[] = {
+	{
+		.compatible = "maxim,max31730",
+	},
+	{ },
+};
+MODULE_DEVICE_TABLE(of, max31730_of_match);
+
+static bool max31730_check_reg_temp(struct i2c_client *client,
+				    int reg)
+{
+	int regval;
+
+	regval = i2c_smbus_read_byte_data(client, reg + 1);
+	return regval < 0 || (regval & 0x0f);
+}
+
+/* Return 0 if detection is successful, -ENODEV otherwise */
+static int max31730_detect(struct i2c_client *client,
+			   struct i2c_board_info *info)
+{
+	struct i2c_adapter *adapter = client->adapter;
+	int regval;
+	int i;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
+				     I2C_FUNC_SMBUS_WORD_DATA))
+		return -ENODEV;
+
+	regval = i2c_smbus_read_byte_data(client, MAX31730_REG_MFG_ID);
+	if (regval != MAX31730_MFG_ID)
+		return -ENODEV;
+	regval = i2c_smbus_read_byte_data(client, MAX31730_REG_MFG_REV);
+	if (regval != MAX31730_MFG_REV)
+		return -ENODEV;
+
+	/* lower 4 bit of temperature and limit registers must be 0 */
+	if (max31730_check_reg_temp(client, MAX31730_REG_TEMP_MIN))
+		return -ENODEV;
+
+	for (i = 0; i < 4; i++) {
+		if (max31730_check_reg_temp(client, MAX31730_REG_TEMP + i * 2))
+			return -ENODEV;
+		if (max31730_check_reg_temp(client,
+					    MAX31730_REG_TEMP_MAX + i * 2))
+			return -ENODEV;
+	}
+
+	strscpy(info->type, "max31730", I2C_NAME_SIZE);
+
+	return 0;
+}
+
+static int max31730_suspend(struct device *dev)
+{
+	struct max31730_data *data = dev_get_drvdata(dev);
+
+	return max31730_write_config(data, MAX31730_STOP, 0);
+}
+
+static int max31730_resume(struct device *dev)
+{
+	struct max31730_data *data = dev_get_drvdata(dev);
+
+	return max31730_write_config(data, 0, MAX31730_STOP);
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(max31730_pm_ops, max31730_suspend, max31730_resume);
+
+static struct i2c_driver max31730_driver = {
+	.class		= I2C_CLASS_HWMON,
+	.driver = {
+		.name	= "max31730",
+		.of_match_table = of_match_ptr(max31730_of_match),
+		.pm	= pm_sleep_ptr(&max31730_pm_ops),
+	},
+	.probe		= max31730_probe,
+	.id_table	= max31730_ids,
+	.detect		= max31730_detect,
+	.address_list	= normal_i2c,
+};
+
+module_i2c_driver(max31730_driver);
+
+MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
+MODULE_DESCRIPTION("MAX31730 driver");
+MODULE_LICENSE("GPL");