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, 594 insertions, 0 deletions

diff --git a/drivers/hwmon/ibmpex.c b/drivers/hwmon/ibmpex.c
new file mode 100644
index 000000000..dec730798
--- /dev/null
+++ b/drivers/hwmon/ibmpex.c
@@ -0,0 +1,594 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * A hwmon driver for the IBM PowerExecutive temperature/power sensors
+ * Copyright (C) 2007 IBM
+ *
+ * Author: Darrick J. Wong <darrick.wong@oracle.com>
+ */
+
+#include <linux/ipmi.h>
+#include <linux/module.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/jiffies.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+
+#define REFRESH_INTERVAL	(2 * HZ)
+#define DRVNAME			"ibmpex"
+
+#define PEX_GET_VERSION		1
+#define PEX_GET_SENSOR_COUNT	2
+#define PEX_GET_SENSOR_NAME	3
+#define PEX_RESET_HIGH_LOW	4
+#define PEX_GET_SENSOR_DATA	6
+
+#define PEX_NET_FUNCTION	0x3A
+#define PEX_COMMAND		0x3C
+
+static inline u16 extract_value(const char *data, int offset)
+{
+	return be16_to_cpup((__be16 *)&data[offset]);
+}
+
+#define TEMP_SENSOR		1
+#define POWER_SENSOR		2
+
+#define PEX_SENSOR_TYPE_LEN	3
+static u8 const power_sensor_sig[] = {0x70, 0x77, 0x72};
+static u8 const temp_sensor_sig[]  = {0x74, 0x65, 0x6D};
+
+#define PEX_MULT_LEN		2
+static u8 const watt_sensor_sig[]  = {0x41, 0x43};
+
+#define PEX_NUM_SENSOR_FUNCS	3
+static const char * const sensor_name_suffixes[] = {
+	"",
+	"_lowest",
+	"_highest"
+};
+
+static void ibmpex_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data);
+static void ibmpex_register_bmc(int iface, struct device *dev);
+static void ibmpex_bmc_gone(int iface);
+
+struct ibmpex_sensor_data {
+	int			in_use;
+	s16			values[PEX_NUM_SENSOR_FUNCS];
+	int			multiplier;
+
+	struct sensor_device_attribute_2	attr[PEX_NUM_SENSOR_FUNCS];
+};
+
+struct ibmpex_bmc_data {
+	struct list_head	list;
+	struct device		*hwmon_dev;
+	struct device		*bmc_device;
+	struct mutex		lock;
+	bool			valid;
+	unsigned long		last_updated;	/* In jiffies */
+
+	struct ipmi_addr	address;
+	struct completion	read_complete;
+	struct ipmi_user	*user;
+	int			interface;
+
+	struct kernel_ipmi_msg	tx_message;
+	unsigned char		tx_msg_data[IPMI_MAX_MSG_LENGTH];
+	long			tx_msgid;
+
+	unsigned char		rx_msg_data[IPMI_MAX_MSG_LENGTH];
+	unsigned long		rx_msg_len;
+	unsigned char		rx_result;
+	int			rx_recv_type;
+
+	unsigned char		sensor_major;
+	unsigned char		sensor_minor;
+
+	unsigned char		num_sensors;
+	struct ibmpex_sensor_data	*sensors;
+};
+
+struct ibmpex_driver_data {
+	struct list_head	bmc_data;
+	struct ipmi_smi_watcher	bmc_events;
+	struct ipmi_user_hndl	ipmi_hndlrs;
+};
+
+static struct ibmpex_driver_data driver_data = {
+	.bmc_data = LIST_HEAD_INIT(driver_data.bmc_data),
+	.bmc_events = {
+		.owner = THIS_MODULE,
+		.new_smi = ibmpex_register_bmc,
+		.smi_gone = ibmpex_bmc_gone,
+	},
+	.ipmi_hndlrs = {
+		.ipmi_recv_hndl = ibmpex_msg_handler,
+	},
+};
+
+static int ibmpex_send_message(struct ibmpex_bmc_data *data)
+{
+	int err;
+
+	err = ipmi_validate_addr(&data->address, sizeof(data->address));
+	if (err)
+		goto out;
+
+	data->tx_msgid++;
+	err = ipmi_request_settime(data->user, &data->address, data->tx_msgid,
+				   &data->tx_message, data, 0, 0, 0);
+	if (err)
+		goto out1;
+
+	return 0;
+out1:
+	dev_err(data->bmc_device, "request_settime=%x\n", err);
+	return err;
+out:
+	dev_err(data->bmc_device, "validate_addr=%x\n", err);
+	return err;
+}
+
+static int ibmpex_ver_check(struct ibmpex_bmc_data *data)
+{
+	data->tx_msg_data[0] = PEX_GET_VERSION;
+	data->tx_message.data_len = 1;
+	ibmpex_send_message(data);
+
+	wait_for_completion(&data->read_complete);
+
+	if (data->rx_result || data->rx_msg_len != 6)
+		return -ENOENT;
+
+	data->sensor_major = data->rx_msg_data[0];
+	data->sensor_minor = data->rx_msg_data[1];
+
+	dev_info(data->bmc_device,
+		 "Found BMC with sensor interface v%d.%d %d-%02d-%02d on interface %d\n",
+		 data->sensor_major,
+		 data->sensor_minor,
+		 extract_value(data->rx_msg_data, 2),
+		 data->rx_msg_data[4],
+		 data->rx_msg_data[5],
+		 data->interface);
+
+	return 0;
+}
+
+static int ibmpex_query_sensor_count(struct ibmpex_bmc_data *data)
+{
+	data->tx_msg_data[0] = PEX_GET_SENSOR_COUNT;
+	data->tx_message.data_len = 1;
+	ibmpex_send_message(data);
+
+	wait_for_completion(&data->read_complete);
+
+	if (data->rx_result || data->rx_msg_len != 1)
+		return -ENOENT;
+
+	return data->rx_msg_data[0];
+}
+
+static int ibmpex_query_sensor_name(struct ibmpex_bmc_data *data, int sensor)
+{
+	data->tx_msg_data[0] = PEX_GET_SENSOR_NAME;
+	data->tx_msg_data[1] = sensor;
+	data->tx_message.data_len = 2;
+	ibmpex_send_message(data);
+
+	wait_for_completion(&data->read_complete);
+
+	if (data->rx_result || data->rx_msg_len < 1)
+		return -ENOENT;
+
+	return 0;
+}
+
+static int ibmpex_query_sensor_data(struct ibmpex_bmc_data *data, int sensor)
+{
+	data->tx_msg_data[0] = PEX_GET_SENSOR_DATA;
+	data->tx_msg_data[1] = sensor;
+	data->tx_message.data_len = 2;
+	ibmpex_send_message(data);
+
+	wait_for_completion(&data->read_complete);
+
+	if (data->rx_result || data->rx_msg_len < 26) {
+		dev_err(data->bmc_device, "Error reading sensor %d.\n",
+			sensor);
+		return -ENOENT;
+	}
+
+	return 0;
+}
+
+static int ibmpex_reset_high_low_data(struct ibmpex_bmc_data *data)
+{
+	data->tx_msg_data[0] = PEX_RESET_HIGH_LOW;
+	data->tx_message.data_len = 1;
+	ibmpex_send_message(data);
+
+	wait_for_completion(&data->read_complete);
+
+	return 0;
+}
+
+static void ibmpex_update_device(struct ibmpex_bmc_data *data)
+{
+	int i, err;
+
+	mutex_lock(&data->lock);
+	if (time_before(jiffies, data->last_updated + REFRESH_INTERVAL) &&
+	    data->valid)
+		goto out;
+
+	for (i = 0; i < data->num_sensors; i++) {
+		if (!data->sensors[i].in_use)
+			continue;
+		err = ibmpex_query_sensor_data(data, i);
+		if (err)
+			continue;
+		data->sensors[i].values[0] =
+			extract_value(data->rx_msg_data, 16);
+		data->sensors[i].values[1] =
+			extract_value(data->rx_msg_data, 18);
+		data->sensors[i].values[2] =
+			extract_value(data->rx_msg_data, 20);
+	}
+
+	data->last_updated = jiffies;
+	data->valid = true;
+
+out:
+	mutex_unlock(&data->lock);
+}
+
+static struct ibmpex_bmc_data *get_bmc_data(int iface)
+{
+	struct ibmpex_bmc_data *p, *next;
+
+	list_for_each_entry_safe(p, next, &driver_data.bmc_data, list)
+		if (p->interface == iface)
+			return p;
+
+	return NULL;
+}
+
+static DEVICE_STRING_ATTR_RO(name, 0444, DRVNAME);
+
+static ssize_t ibmpex_show_sensor(struct device *dev,
+				  struct device_attribute *devattr,
+				  char *buf)
+{
+	struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(devattr);
+	struct ibmpex_bmc_data *data = dev_get_drvdata(dev);
+	int mult = data->sensors[attr->index].multiplier;
+	ibmpex_update_device(data);
+
+	return sprintf(buf, "%d\n",
+		       data->sensors[attr->index].values[attr->nr] * mult);
+}
+
+static ssize_t ibmpex_high_low_store(struct device *dev,
+				     struct device_attribute *devattr,
+				     const char *buf, size_t count)
+{
+	struct ibmpex_bmc_data *data = dev_get_drvdata(dev);
+
+	ibmpex_reset_high_low_data(data);
+
+	return count;
+}
+
+static SENSOR_DEVICE_ATTR_WO(reset_high_low, ibmpex_high_low, 0);
+
+static int is_power_sensor(const char *sensor_id, int len)
+{
+	if (len < PEX_SENSOR_TYPE_LEN)
+		return 0;
+
+	if (!memcmp(sensor_id, power_sensor_sig, PEX_SENSOR_TYPE_LEN))
+		return 1;
+	return 0;
+}
+
+static int is_temp_sensor(const char *sensor_id, int len)
+{
+	if (len < PEX_SENSOR_TYPE_LEN)
+		return 0;
+
+	if (!memcmp(sensor_id, temp_sensor_sig, PEX_SENSOR_TYPE_LEN))
+		return 1;
+	return 0;
+}
+
+static int power_sensor_multiplier(struct ibmpex_bmc_data *data,
+				   const char *sensor_id, int len)
+{
+	int i;
+
+	if (data->sensor_major == 2)
+		return 1000000;
+
+	for (i = PEX_SENSOR_TYPE_LEN; i < len - 1; i++)
+		if (!memcmp(&sensor_id[i], watt_sensor_sig, PEX_MULT_LEN))
+			return 1000000;
+
+	return 100000;
+}
+
+static int create_sensor(struct ibmpex_bmc_data *data, int type,
+			 int counter, int sensor, int func)
+{
+	int err;
+	char *n;
+
+	n = kmalloc(32, GFP_KERNEL);
+	if (!n)
+		return -ENOMEM;
+
+	if (type == TEMP_SENSOR)
+		sprintf(n, "temp%d_input%s",
+			counter, sensor_name_suffixes[func]);
+	else if (type == POWER_SENSOR)
+		sprintf(n, "power%d_average%s",
+			counter, sensor_name_suffixes[func]);
+
+	sysfs_attr_init(&data->sensors[sensor].attr[func].dev_attr.attr);
+	data->sensors[sensor].attr[func].dev_attr.attr.name = n;
+	data->sensors[sensor].attr[func].dev_attr.attr.mode = 0444;
+	data->sensors[sensor].attr[func].dev_attr.show = ibmpex_show_sensor;
+	data->sensors[sensor].attr[func].index = sensor;
+	data->sensors[sensor].attr[func].nr = func;
+
+	err = device_create_file(data->bmc_device,
+				 &data->sensors[sensor].attr[func].dev_attr);
+	if (err) {
+		data->sensors[sensor].attr[func].dev_attr.attr.name = NULL;
+		kfree(n);
+		return err;
+	}
+
+	return 0;
+}
+
+static int ibmpex_find_sensors(struct ibmpex_bmc_data *data)
+{
+	int i, j, err;
+	int sensor_type;
+	int sensor_counter;
+	int num_power = 0;
+	int num_temp = 0;
+
+	err = ibmpex_query_sensor_count(data);
+	if (err <= 0)
+		return -ENOENT;
+	data->num_sensors = err;
+
+	data->sensors = kzalloc_objs(*data->sensors, data->num_sensors);
+	if (!data->sensors)
+		return -ENOMEM;
+
+	for (i = 0; i < data->num_sensors; i++) {
+		err = ibmpex_query_sensor_name(data, i);
+		if (err)
+			continue;
+
+		if (is_power_sensor(data->rx_msg_data, data->rx_msg_len)) {
+			sensor_type = POWER_SENSOR;
+			num_power++;
+			sensor_counter = num_power;
+			data->sensors[i].multiplier =
+				power_sensor_multiplier(data,
+							data->rx_msg_data,
+							data->rx_msg_len);
+		} else if (is_temp_sensor(data->rx_msg_data,
+					  data->rx_msg_len)) {
+			sensor_type = TEMP_SENSOR;
+			num_temp++;
+			sensor_counter = num_temp;
+			data->sensors[i].multiplier = 1000;
+		} else
+			continue;
+
+		data->sensors[i].in_use = 1;
+
+		/* Create attributes */
+		for (j = 0; j < PEX_NUM_SENSOR_FUNCS; j++) {
+			err = create_sensor(data, sensor_type, sensor_counter,
+					    i, j);
+			if (err)
+				goto exit_remove;
+		}
+	}
+
+	err = device_create_file(data->bmc_device,
+			&sensor_dev_attr_reset_high_low.dev_attr);
+	if (err)
+		goto exit_remove;
+
+	err = device_create_file(data->bmc_device, &dev_attr_name.attr);
+	if (err)
+		goto exit_remove;
+
+	return 0;
+
+exit_remove:
+	device_remove_file(data->bmc_device,
+			   &sensor_dev_attr_reset_high_low.dev_attr);
+	device_remove_file(data->bmc_device, &dev_attr_name.attr);
+	for (i = 0; i < data->num_sensors; i++)
+		for (j = 0; j < PEX_NUM_SENSOR_FUNCS; j++) {
+			if (!data->sensors[i].attr[j].dev_attr.attr.name)
+				continue;
+			device_remove_file(data->bmc_device,
+				&data->sensors[i].attr[j].dev_attr);
+			kfree(data->sensors[i].attr[j].dev_attr.attr.name);
+		}
+
+	kfree(data->sensors);
+	return err;
+}
+
+static void ibmpex_register_bmc(int iface, struct device *dev)
+{
+	struct ibmpex_bmc_data *data;
+	int err;
+
+	data = kzalloc_obj(*data);
+	if (!data)
+		return;
+
+	data->address.addr_type = IPMI_SYSTEM_INTERFACE_ADDR_TYPE;
+	data->address.channel = IPMI_BMC_CHANNEL;
+	data->address.data[0] = 0;
+	data->interface = iface;
+	data->bmc_device = dev;
+
+	/* Create IPMI messaging interface user */
+	err = ipmi_create_user(data->interface, &driver_data.ipmi_hndlrs,
+			       data, &data->user);
+	if (err < 0) {
+		dev_err(dev,
+			"Unable to register user with IPMI interface %d\n",
+			data->interface);
+		goto out;
+	}
+
+	mutex_init(&data->lock);
+
+	/* Initialize message */
+	data->tx_msgid = 0;
+	init_completion(&data->read_complete);
+	data->tx_message.netfn = PEX_NET_FUNCTION;
+	data->tx_message.cmd = PEX_COMMAND;
+	data->tx_message.data = data->tx_msg_data;
+
+	/* Does this BMC support PowerExecutive? */
+	err = ibmpex_ver_check(data);
+	if (err)
+		goto out_user;
+
+	/* Register the BMC as a HWMON class device */
+	data->hwmon_dev = hwmon_device_register(data->bmc_device);
+
+	if (IS_ERR(data->hwmon_dev)) {
+		dev_err(data->bmc_device,
+			"Unable to register hwmon device for IPMI interface %d\n",
+			data->interface);
+		goto out_user;
+	}
+
+	/* finally add the new bmc data to the bmc data list */
+	dev_set_drvdata(dev, data);
+	list_add_tail(&data->list, &driver_data.bmc_data);
+
+	/* Now go find all the sensors */
+	err = ibmpex_find_sensors(data);
+	if (err) {
+		dev_err(data->bmc_device, "Error %d finding sensors\n", err);
+		goto out_register;
+	}
+
+	return;
+
+out_register:
+	list_del(&data->list);
+	hwmon_device_unregister(data->hwmon_dev);
+out_user:
+	ipmi_destroy_user(data->user);
+out:
+	kfree(data);
+}
+
+static void ibmpex_bmc_delete(struct ibmpex_bmc_data *data)
+{
+	int i, j;
+
+	device_remove_file(data->bmc_device,
+			   &sensor_dev_attr_reset_high_low.dev_attr);
+	device_remove_file(data->bmc_device, &dev_attr_name.attr);
+	for (i = 0; i < data->num_sensors; i++)
+		for (j = 0; j < PEX_NUM_SENSOR_FUNCS; j++) {
+			if (!data->sensors[i].attr[j].dev_attr.attr.name)
+				continue;
+			device_remove_file(data->bmc_device,
+				&data->sensors[i].attr[j].dev_attr);
+			kfree(data->sensors[i].attr[j].dev_attr.attr.name);
+		}
+
+	list_del(&data->list);
+	dev_set_drvdata(data->bmc_device, NULL);
+	hwmon_device_unregister(data->hwmon_dev);
+	ipmi_destroy_user(data->user);
+	kfree(data->sensors);
+	kfree(data);
+}
+
+static void ibmpex_bmc_gone(int iface)
+{
+	struct ibmpex_bmc_data *data = get_bmc_data(iface);
+
+	if (!data)
+		return;
+
+	ibmpex_bmc_delete(data);
+}
+
+static void ibmpex_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data)
+{
+	struct ibmpex_bmc_data *data = user_msg_data;
+
+	if (msg->msgid != data->tx_msgid) {
+		dev_err(data->bmc_device,
+			"Mismatch between received msgid (%02x) and transmitted msgid (%02x)!\n",
+			(int)msg->msgid,
+			(int)data->tx_msgid);
+		ipmi_free_recv_msg(msg);
+		return;
+	}
+
+	data->rx_recv_type = msg->recv_type;
+	if (msg->msg.data_len > 0)
+		data->rx_result = msg->msg.data[0];
+	else
+		data->rx_result = IPMI_UNKNOWN_ERR_COMPLETION_CODE;
+
+	if (msg->msg.data_len > 1) {
+		data->rx_msg_len = msg->msg.data_len - 1;
+		memcpy(data->rx_msg_data, msg->msg.data + 1, data->rx_msg_len);
+	} else
+		data->rx_msg_len = 0;
+
+	ipmi_free_recv_msg(msg);
+	complete(&data->read_complete);
+}
+
+static int __init ibmpex_init(void)
+{
+	return ipmi_smi_watcher_register(&driver_data.bmc_events);
+}
+
+static void __exit ibmpex_exit(void)
+{
+	struct ibmpex_bmc_data *p, *next;
+
+	ipmi_smi_watcher_unregister(&driver_data.bmc_events);
+	list_for_each_entry_safe(p, next, &driver_data.bmc_data, list)
+		ibmpex_bmc_delete(p);
+}
+
+MODULE_AUTHOR("Darrick J. Wong <darrick.wong@oracle.com>");
+MODULE_DESCRIPTION("IBM PowerExecutive power/temperature sensor driver");
+MODULE_LICENSE("GPL");
+
+module_init(ibmpex_init);
+module_exit(ibmpex_exit);
+
+MODULE_ALIAS("dmi:bvnIBM:*:pnIBMSystemx3350-*");
+MODULE_ALIAS("dmi:bvnIBM:*:pnIBMSystemx3550-*");
+MODULE_ALIAS("dmi:bvnIBM:*:pnIBMSystemx3650-*");
+MODULE_ALIAS("dmi:bvnIBM:*:pnIBMSystemx3655-*");
+MODULE_ALIAS("dmi:bvnIBM:*:pnIBMSystemx3755-*");