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, 483 insertions, 0 deletions

diff --git a/drivers/hwmon/tmp421.c b/drivers/hwmon/tmp421.c
new file mode 100644
index 000000000..ed00ccfdd
--- /dev/null
+++ b/drivers/hwmon/tmp421.c
@@ -0,0 +1,483 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* tmp421.c
+ *
+ * Copyright (C) 2009 Andre Prendel <andre.prendel@gmx.de>
+ * Preliminary support by:
+ * Melvin Rook, Raymond Ng
+ */
+
+/*
+ * Driver for the Texas Instruments TMP421 SMBus temperature sensor IC.
+ * Supported models: TMP421, TMP422, TMP423, TMP441, TMP442
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/jiffies.h>
+#include <linux/i2c.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/sysfs.h>
+
+/* Addresses to scan */
+static const unsigned short normal_i2c[] = { 0x2a, 0x4c, 0x4d, 0x4e, 0x4f,
+					     I2C_CLIENT_END };
+
+enum chips { tmp421, tmp422, tmp423, tmp441, tmp442 };
+
+#define MAX_CHANNELS				4
+/* The TMP421 registers */
+#define TMP421_STATUS_REG			0x08
+#define TMP421_CONFIG_REG_1			0x09
+#define TMP421_CONFIG_REG_2			0x0A
+#define TMP421_CONFIG_REG_REN(x)		(BIT(3 + (x)))
+#define TMP421_CONFIG_REG_REN_MASK		GENMASK(6, 3)
+#define TMP421_CONVERSION_RATE_REG		0x0B
+#define TMP421_N_FACTOR_REG_1			0x21
+#define TMP421_MANUFACTURER_ID_REG		0xFE
+#define TMP421_DEVICE_ID_REG			0xFF
+
+static const u8 TMP421_TEMP_MSB[MAX_CHANNELS]	= { 0x00, 0x01, 0x02, 0x03 };
+static const u8 TMP421_TEMP_LSB[MAX_CHANNELS]	= { 0x10, 0x11, 0x12, 0x13 };
+
+/* Flags */
+#define TMP421_CONFIG_SHUTDOWN			0x40
+#define TMP421_CONFIG_RANGE			0x04
+
+/* Manufacturer / Device ID's */
+#define TMP421_MANUFACTURER_ID			0x55
+#define TMP421_DEVICE_ID			0x21
+#define TMP422_DEVICE_ID			0x22
+#define TMP423_DEVICE_ID			0x23
+#define TMP441_DEVICE_ID			0x41
+#define TMP442_DEVICE_ID			0x42
+
+static const struct i2c_device_id tmp421_id[] = {
+	{ .name = "tmp421", .driver_data = 2 },
+	{ .name = "tmp422", .driver_data = 3 },
+	{ .name = "tmp423", .driver_data = 4 },
+	{ .name = "tmp441", .driver_data = 2 },
+	{ .name = "tmp442", .driver_data = 3 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, tmp421_id);
+
+static const struct of_device_id __maybe_unused tmp421_of_match[] = {
+	{
+		.compatible = "ti,tmp421",
+		.data = (void *)2
+	},
+	{
+		.compatible = "ti,tmp422",
+		.data = (void *)3
+	},
+	{
+		.compatible = "ti,tmp423",
+		.data = (void *)4
+	},
+	{
+		.compatible = "ti,tmp441",
+		.data = (void *)2
+	},
+	{
+		.compatible = "ti,tmp442",
+		.data = (void *)3
+	},
+	{ },
+};
+MODULE_DEVICE_TABLE(of, tmp421_of_match);
+
+struct tmp421_channel {
+	const char *label;
+	bool enabled;
+	s16 temp;
+};
+
+struct tmp421_data {
+	struct i2c_client *client;
+	u32 temp_config[MAX_CHANNELS + 1];
+	struct hwmon_channel_info temp_info;
+	const struct hwmon_channel_info *info[2];
+	struct hwmon_chip_info chip;
+	bool valid;
+	unsigned long last_updated;
+	unsigned long channels;
+	u8 config;
+	struct tmp421_channel channel[MAX_CHANNELS];
+};
+
+static int temp_from_raw(u16 reg, bool extended)
+{
+	/* Mask out status bits */
+	int temp = reg & ~0xf;
+
+	if (extended)
+		temp = temp - 64 * 256;
+	else
+		temp = (s16)temp;
+
+	return DIV_ROUND_CLOSEST(temp * 1000, 256);
+}
+
+static int tmp421_update_device(struct tmp421_data *data)
+{
+	struct i2c_client *client = data->client;
+	int ret = 0;
+	int i;
+
+	if (time_after(jiffies, data->last_updated + (HZ / 2)) ||
+	    !data->valid) {
+		data->valid = false;
+		ret = i2c_smbus_read_byte_data(client, TMP421_CONFIG_REG_1);
+		if (ret < 0)
+			return ret;
+		data->config = ret;
+
+		for (i = 0; i < data->channels; i++) {
+			ret = i2c_smbus_read_byte_data(client, TMP421_TEMP_MSB[i]);
+			if (ret < 0)
+				return ret;
+			data->channel[i].temp = ret << 8;
+
+			ret = i2c_smbus_read_byte_data(client, TMP421_TEMP_LSB[i]);
+			if (ret < 0)
+				return ret;
+			data->channel[i].temp |= ret;
+		}
+		data->last_updated = jiffies;
+		data->valid = true;
+	}
+	return 0;
+}
+
+static int tmp421_enable_channels(struct tmp421_data *data)
+{
+	int err;
+	struct i2c_client *client = data->client;
+	struct device *dev = &client->dev;
+	int old = i2c_smbus_read_byte_data(client, TMP421_CONFIG_REG_2);
+	int new, i;
+
+	if (old < 0) {
+		dev_err(dev, "error reading register, can't disable channels\n");
+		return old;
+	}
+
+	new = old & ~TMP421_CONFIG_REG_REN_MASK;
+	for (i = 0; i < data->channels; i++)
+		if (data->channel[i].enabled)
+			new |= TMP421_CONFIG_REG_REN(i);
+
+	if (new == old)
+		return 0;
+
+	err = i2c_smbus_write_byte_data(client, TMP421_CONFIG_REG_2, new);
+	if (err < 0)
+		dev_err(dev, "error writing register, can't disable channels\n");
+
+	return err;
+}
+
+static int tmp421_read(struct device *dev, enum hwmon_sensor_types type,
+		       u32 attr, int channel, long *val)
+{
+	struct tmp421_data *tmp421 = dev_get_drvdata(dev);
+	int ret = 0;
+
+	ret = tmp421_update_device(tmp421);
+	if (ret)
+		return ret;
+
+	switch (attr) {
+	case hwmon_temp_input:
+		if (!tmp421->channel[channel].enabled)
+			return -ENODATA;
+		*val = temp_from_raw(tmp421->channel[channel].temp,
+				     tmp421->config & TMP421_CONFIG_RANGE);
+		return 0;
+	case hwmon_temp_fault:
+		if (!tmp421->channel[channel].enabled)
+			return -ENODATA;
+		/*
+		 * Any of OPEN or /PVLD bits indicate a hardware mulfunction
+		 * and the conversion result may be incorrect
+		 */
+		*val = !!(tmp421->channel[channel].temp & 0x03);
+		return 0;
+	case hwmon_temp_enable:
+		*val = tmp421->channel[channel].enabled;
+		return 0;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+}
+
+static int tmp421_read_string(struct device *dev, enum hwmon_sensor_types type,
+			     u32 attr, int channel, const char **str)
+{
+	struct tmp421_data *data = dev_get_drvdata(dev);
+
+	*str = data->channel[channel].label;
+
+	return 0;
+}
+
+static int tmp421_write(struct device *dev, enum hwmon_sensor_types type,
+			u32 attr, int channel, long val)
+{
+	struct tmp421_data *data = dev_get_drvdata(dev);
+	int ret;
+
+	switch (attr) {
+	case hwmon_temp_enable:
+		data->channel[channel].enabled = val;
+		ret = tmp421_enable_channels(data);
+		break;
+	default:
+	    ret = -EOPNOTSUPP;
+	}
+
+	return ret;
+}
+
+static umode_t tmp421_is_visible(const void *data, enum hwmon_sensor_types type,
+				 u32 attr, int channel)
+{
+	switch (attr) {
+	case hwmon_temp_fault:
+	case hwmon_temp_input:
+	case hwmon_temp_label:
+		return 0444;
+	case hwmon_temp_enable:
+		return 0644;
+	default:
+		return 0;
+	}
+}
+
+static int tmp421_init_client(struct tmp421_data *data)
+{
+	int config, config_orig;
+	struct i2c_client *client = data->client;
+
+	/* Set the conversion rate to 2 Hz */
+	i2c_smbus_write_byte_data(client, TMP421_CONVERSION_RATE_REG, 0x05);
+
+	/* Start conversions (disable shutdown if necessary) */
+	config = i2c_smbus_read_byte_data(client, TMP421_CONFIG_REG_1);
+	if (config < 0) {
+		dev_err(&client->dev,
+			"Could not read configuration register (%d)\n", config);
+		return config;
+	}
+
+	config_orig = config;
+	config &= ~TMP421_CONFIG_SHUTDOWN;
+
+	if (config != config_orig) {
+		dev_info(&client->dev, "Enable monitoring chip\n");
+		i2c_smbus_write_byte_data(client, TMP421_CONFIG_REG_1, config);
+	}
+
+	return tmp421_enable_channels(data);
+}
+
+static int tmp421_detect(struct i2c_client *client,
+			 struct i2c_board_info *info)
+{
+	enum chips kind;
+	struct i2c_adapter *adapter = client->adapter;
+	static const char * const names[] = {
+		"TMP421", "TMP422", "TMP423",
+		"TMP441", "TMP442"
+	};
+	int addr = client->addr;
+	u8 reg;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+		return -ENODEV;
+
+	reg = i2c_smbus_read_byte_data(client, TMP421_MANUFACTURER_ID_REG);
+	if (reg != TMP421_MANUFACTURER_ID)
+		return -ENODEV;
+
+	reg = i2c_smbus_read_byte_data(client, TMP421_CONVERSION_RATE_REG);
+	if (reg & 0xf8)
+		return -ENODEV;
+
+	reg = i2c_smbus_read_byte_data(client, TMP421_STATUS_REG);
+	if (reg & 0x7f)
+		return -ENODEV;
+
+	reg = i2c_smbus_read_byte_data(client, TMP421_DEVICE_ID_REG);
+	switch (reg) {
+	case TMP421_DEVICE_ID:
+		kind = tmp421;
+		break;
+	case TMP422_DEVICE_ID:
+		if (addr == 0x2a)
+			return -ENODEV;
+		kind = tmp422;
+		break;
+	case TMP423_DEVICE_ID:
+		if (addr != 0x4c && addr != 0x4d)
+			return -ENODEV;
+		kind = tmp423;
+		break;
+	case TMP441_DEVICE_ID:
+		kind = tmp441;
+		break;
+	case TMP442_DEVICE_ID:
+		if (addr != 0x4c && addr != 0x4d)
+			return -ENODEV;
+		kind = tmp442;
+		break;
+	default:
+		return -ENODEV;
+	}
+
+	strscpy(info->type, tmp421_id[kind].name, I2C_NAME_SIZE);
+	dev_info(&adapter->dev, "Detected TI %s chip at 0x%02x\n",
+		 names[kind], client->addr);
+
+	return 0;
+}
+
+static int tmp421_probe_child_from_dt(struct i2c_client *client,
+				      struct device_node *child,
+				      struct tmp421_data *data)
+
+{
+	struct device *dev = &client->dev;
+	u32 i;
+	s32 val;
+	int err;
+
+	err = of_property_read_u32(child, "reg", &i);
+	if (err) {
+		dev_err(dev, "missing reg property of %pOFn\n", child);
+		return err;
+	}
+
+	if (i >= data->channels) {
+		dev_err(dev, "invalid reg %d of %pOFn\n", i, child);
+		return -EINVAL;
+	}
+
+	err = of_property_read_string(child, "label", &data->channel[i].label);
+	if (err == -ENODATA || err == -EILSEQ) {
+		dev_err(dev, "invalid label property in %pOFn\n", child);
+		return err;
+	}
+	if (data->channel[i].label)
+		data->temp_config[i] |= HWMON_T_LABEL;
+
+	data->channel[i].enabled = of_device_is_available(child);
+
+	err = of_property_read_s32(child, "ti,n-factor", &val);
+	if (!err) {
+		if (i == 0) {
+			dev_err(dev, "n-factor can't be set for internal channel\n");
+			return -EINVAL;
+		}
+
+		if (val > 127 || val < -128) {
+			dev_err(dev, "n-factor for channel %d invalid (%d)\n",
+				i, val);
+			return -EINVAL;
+		}
+		i2c_smbus_write_byte_data(client, TMP421_N_FACTOR_REG_1 + i - 1,
+					  val);
+	}
+
+	return 0;
+}
+
+static int tmp421_probe_from_dt(struct i2c_client *client, struct tmp421_data *data)
+{
+	struct device *dev = &client->dev;
+	const struct device_node *np = dev->of_node;
+	int err;
+
+	for_each_child_of_node_scoped(np, child) {
+		if (strcmp(child->name, "channel"))
+			continue;
+
+		err = tmp421_probe_child_from_dt(client, child, data);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static const struct hwmon_ops tmp421_ops = {
+	.is_visible = tmp421_is_visible,
+	.read = tmp421_read,
+	.read_string = tmp421_read_string,
+	.write = tmp421_write,
+};
+
+static int tmp421_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct device *hwmon_dev;
+	struct tmp421_data *data;
+	int i, err;
+
+	data = devm_kzalloc(dev, sizeof(struct tmp421_data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->channels = (unsigned long)i2c_get_match_data(client);
+	data->client = client;
+
+	for (i = 0; i < data->channels; i++) {
+		data->temp_config[i] = HWMON_T_INPUT | HWMON_T_FAULT | HWMON_T_ENABLE;
+		data->channel[i].enabled = true;
+	}
+
+	err = tmp421_probe_from_dt(client, data);
+	if (err)
+		return err;
+
+	err = tmp421_init_client(data);
+	if (err)
+		return err;
+
+	data->chip.ops = &tmp421_ops;
+	data->chip.info = data->info;
+
+	data->info[0] = &data->temp_info;
+
+	data->temp_info.type = hwmon_temp;
+	data->temp_info.config = data->temp_config;
+
+	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
+							 data,
+							 &data->chip,
+							 NULL);
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static struct i2c_driver tmp421_driver = {
+	.class = I2C_CLASS_HWMON,
+	.driver = {
+		.name	= "tmp421",
+		.of_match_table = of_match_ptr(tmp421_of_match),
+	},
+	.probe = tmp421_probe,
+	.id_table = tmp421_id,
+	.detect = tmp421_detect,
+	.address_list = normal_i2c,
+};
+
+module_i2c_driver(tmp421_driver);
+
+MODULE_AUTHOR("Andre Prendel <andre.prendel@gmx.de>");
+MODULE_DESCRIPTION("Texas Instruments TMP421/422/423/441/442 temperature sensor driver");
+MODULE_LICENSE("GPL");