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, 319 insertions, 0 deletions

diff --git a/drivers/hwmon/max1668.c b/drivers/hwmon/max1668.c
new file mode 100644
index 000000000..32548f564
--- /dev/null
+++ b/drivers/hwmon/max1668.c
@@ -0,0 +1,319 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2011 David George <david.george@ska.ac.za>
+ *
+ * based on adm1021.c
+ * some credit to Christoph Scheurer, but largely a rewrite
+ */
+
+#include <linux/bitops.h>
+#include <linux/bits.h>
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+/* Addresses to scan */
+static const unsigned short max1668_addr_list[] = {
+	0x18, 0x19, 0x1a, 0x29, 0x2a, 0x2b, 0x4c, 0x4d, 0x4e, I2C_CLIENT_END };
+
+/* max1668 registers */
+
+#define MAX1668_REG_TEMP(nr)	(nr)
+#define MAX1668_REG_STAT1	0x05
+#define MAX1668_REG_STAT2	0x06
+#define MAX1668_REG_MAN_ID	0xfe
+#define MAX1668_REG_DEV_ID	0xff
+
+/* limits */
+
+/* high limits */
+#define MAX1668_REG_LIMH(nr)	(0x08 + 2 * (nr))
+/* read low limits */
+#define MAX1668_REG_LIML(nr)	(0x09 + 2 * (nr))
+
+/* manufacturer and device ID Constants */
+#define MAN_ID_MAXIM		0x4d
+#define DEV_ID_MAX1668		0x3
+#define DEV_ID_MAX1805		0x5
+#define DEV_ID_MAX1989		0xb
+
+/* read only mode module parameter */
+static bool read_only;
+module_param(read_only, bool, 0);
+MODULE_PARM_DESC(read_only, "Don't set any values, read only mode");
+
+struct max1668_data {
+	struct regmap *regmap;
+	int channels;
+};
+
+static int max1668_read(struct device *dev, enum hwmon_sensor_types type,
+			u32 attr, int channel, long *val)
+{
+	struct max1668_data *data = dev_get_drvdata(dev);
+	struct regmap *regmap = data->regmap;
+	u32 regs[2] = { MAX1668_REG_STAT1, MAX1668_REG_TEMP(channel) };
+	u8 regvals[2];
+	u32 regval;
+	int ret;
+
+	switch (attr) {
+	case hwmon_temp_input:
+		ret = regmap_read(regmap, MAX1668_REG_TEMP(channel), &regval);
+		if (ret)
+			return ret;
+		*val = sign_extend32(regval, 7) * 1000;
+		break;
+	case hwmon_temp_min:
+		ret = regmap_read(regmap, MAX1668_REG_LIML(channel), &regval);
+		if (ret)
+			return ret;
+		*val = sign_extend32(regval, 7) * 1000;
+		break;
+	case hwmon_temp_max:
+		ret = regmap_read(regmap, MAX1668_REG_LIMH(channel), &regval);
+		if (ret)
+			return ret;
+		*val = sign_extend32(regval, 7) * 1000;
+		break;
+	case hwmon_temp_min_alarm:
+		ret = regmap_read(regmap,
+				  channel ? MAX1668_REG_STAT2 : MAX1668_REG_STAT1,
+				  &regval);
+		if (ret)
+			return ret;
+		if (channel)
+			*val = !!(regval & BIT(9 - channel * 2));
+		else
+			*val = !!(regval & BIT(5));
+		break;
+	case hwmon_temp_max_alarm:
+		ret = regmap_read(regmap,
+				  channel ? MAX1668_REG_STAT2 : MAX1668_REG_STAT1,
+				  &regval);
+		if (ret)
+			return ret;
+		if (channel)
+			*val = !!(regval & BIT(8 - channel * 2));
+		else
+			*val = !!(regval & BIT(6));
+		break;
+	case hwmon_temp_fault:
+		ret = regmap_multi_reg_read(regmap, regs, regvals, 2);
+		if (ret)
+			return ret;
+		*val = !!((regvals[0] & BIT(4)) && regvals[1] == 127);
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+	return 0;
+}
+
+static int max1668_write(struct device *dev, enum hwmon_sensor_types type,
+			 u32 attr, int channel, long val)
+{
+	struct max1668_data *data = dev_get_drvdata(dev);
+	struct regmap *regmap = data->regmap;
+
+	val = clamp_val(val / 1000, -128, 127);
+
+	switch (attr) {
+	case hwmon_temp_min:
+		return regmap_write(regmap, MAX1668_REG_LIML(channel), val);
+	case hwmon_temp_max:
+		return regmap_write(regmap, MAX1668_REG_LIMH(channel), val);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static umode_t max1668_is_visible(const void *_data, enum hwmon_sensor_types type,
+				  u32 attr, int channel)
+{
+	const struct max1668_data *data = _data;
+
+	if (channel >= data->channels)
+		return 0;
+
+	switch (attr) {
+	case hwmon_temp_min:
+	case hwmon_temp_max:
+		return read_only ? 0444 : 0644;
+	case hwmon_temp_input:
+	case hwmon_temp_min_alarm:
+	case hwmon_temp_max_alarm:
+		return 0444;
+	case hwmon_temp_fault:
+		if (channel)
+			return 0444;
+		break;
+	default:
+		break;
+	}
+	return 0;
+}
+
+static const struct hwmon_channel_info * const max1668_info[] = {
+	HWMON_CHANNEL_INFO(temp,
+			   HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
+			   HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM,
+			   HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
+			   HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM |
+			   HWMON_T_FAULT,
+			   HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
+			   HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM |
+			   HWMON_T_FAULT,
+			   HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
+			   HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM |
+			   HWMON_T_FAULT,
+			   HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
+			   HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM |
+			   HWMON_T_FAULT),
+	NULL
+};
+
+static const struct hwmon_ops max1668_hwmon_ops = {
+	.is_visible = max1668_is_visible,
+	.read = max1668_read,
+	.write = max1668_write,
+};
+
+static const struct hwmon_chip_info max1668_chip_info = {
+	.ops = &max1668_hwmon_ops,
+	.info = max1668_info,
+};
+
+/* Return 0 if detection is successful, -ENODEV otherwise */
+static int max1668_detect(struct i2c_client *client,
+			  struct i2c_board_info *info)
+{
+	struct i2c_adapter *adapter = client->adapter;
+	const char *type_name;
+	int man_id, dev_id;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+		return -ENODEV;
+
+	/* Check for unsupported part */
+	man_id = i2c_smbus_read_byte_data(client, MAX1668_REG_MAN_ID);
+	if (man_id != MAN_ID_MAXIM)
+		return -ENODEV;
+
+	dev_id = i2c_smbus_read_byte_data(client, MAX1668_REG_DEV_ID);
+	if (dev_id < 0)
+		return -ENODEV;
+
+	type_name = NULL;
+	if (dev_id == DEV_ID_MAX1668)
+		type_name = "max1668";
+	else if (dev_id == DEV_ID_MAX1805)
+		type_name = "max1805";
+	else if (dev_id == DEV_ID_MAX1989)
+		type_name = "max1989";
+
+	if (!type_name)
+		return -ENODEV;
+
+	strscpy(info->type, type_name, I2C_NAME_SIZE);
+
+	return 0;
+}
+
+/* regmap */
+
+static int max1668_reg_read(void *context, unsigned int reg, unsigned int *val)
+{
+	int ret;
+
+	ret = i2c_smbus_read_byte_data(context, reg);
+	if (ret < 0)
+		return ret;
+
+	*val = ret;
+	return 0;
+}
+
+static int max1668_reg_write(void *context, unsigned int reg, unsigned int val)
+{
+	return i2c_smbus_write_byte_data(context, reg + 11, val);
+}
+
+static bool max1668_regmap_is_volatile(struct device *dev, unsigned int reg)
+{
+	return reg <= MAX1668_REG_STAT2;
+}
+
+static bool max1668_regmap_is_writeable(struct device *dev, unsigned int reg)
+{
+	return reg > MAX1668_REG_STAT2 && reg <= MAX1668_REG_LIML(4);
+}
+
+static const struct regmap_config max1668_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.cache_type = REGCACHE_MAPLE,
+	.volatile_reg = max1668_regmap_is_volatile,
+	.writeable_reg = max1668_regmap_is_writeable,
+};
+
+static const struct regmap_bus max1668_regmap_bus = {
+	.reg_write = max1668_reg_write,
+	.reg_read = max1668_reg_read,
+};
+
+static int max1668_probe(struct i2c_client *client)
+{
+	struct i2c_adapter *adapter = client->adapter;
+	struct device *dev = &client->dev;
+	struct device *hwmon_dev;
+	struct max1668_data *data;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+		return -ENODEV;
+
+	data = devm_kzalloc(dev, sizeof(struct max1668_data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->regmap = devm_regmap_init(dev, &max1668_regmap_bus, client,
+					&max1668_regmap_config);
+	if (IS_ERR(data->regmap))
+		return PTR_ERR(data->regmap);
+
+	data->channels = (uintptr_t)i2c_get_match_data(client);
+
+	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, data,
+							 &max1668_chip_info, NULL);
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct i2c_device_id max1668_id[] = {
+	{ .name = "max1668", .driver_data = 5 },
+	{ .name = "max1805", .driver_data = 3 },
+	{ .name = "max1989", .driver_data = 5 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, max1668_id);
+
+/* This is the driver that will be inserted */
+static struct i2c_driver max1668_driver = {
+	.class = I2C_CLASS_HWMON,
+	.driver = {
+		  .name	= "max1668",
+		  },
+	.probe = max1668_probe,
+	.id_table = max1668_id,
+	.detect	= max1668_detect,
+	.address_list = max1668_addr_list,
+};
+
+module_i2c_driver(max1668_driver);
+
+MODULE_AUTHOR("David George <david.george@ska.ac.za>");
+MODULE_DESCRIPTION("MAX1668 remote temperature sensor driver");
+MODULE_LICENSE("GPL");