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, 308 insertions, 0 deletions

diff --git a/drivers/misc/apds9802als.c b/drivers/misc/apds9802als.c
new file mode 100644
index 000000000..1488e2881
--- /dev/null
+++ b/drivers/misc/apds9802als.c
@@ -0,0 +1,308 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * apds9802als.c - apds9802  ALS Driver
+ *
+ * Copyright (C) 2009 Intel Corp
+ *
+ *  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/err.h>
+#include <linux/delay.h>
+#include <linux/mutex.h>
+#include <linux/sysfs.h>
+#include <linux/pm_runtime.h>
+
+#define ALS_MIN_RANGE_VAL 1
+#define ALS_MAX_RANGE_VAL 2
+#define POWER_STA_ENABLE 1
+#define POWER_STA_DISABLE 0
+
+#define DRIVER_NAME "apds9802als"
+
+struct als_data {
+	struct mutex mutex;
+};
+
+static ssize_t als_sensing_range_show(struct device *dev,
+			struct device_attribute *attr,  char *buf)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	int  val;
+
+	val = i2c_smbus_read_byte_data(client, 0x81);
+	if (val < 0)
+		return val;
+	if (val & 1)
+		return sprintf(buf, "4095\n");
+	else
+		return sprintf(buf, "65535\n");
+}
+
+static int als_wait_for_data_ready(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	int ret;
+	int retry = 10;
+
+	do {
+		msleep(30);
+		ret = i2c_smbus_read_byte_data(client, 0x86);
+	} while (!(ret & 0x80) && retry--);
+
+	if (retry < 0) {
+		dev_warn(dev, "timeout waiting for data ready\n");
+		return -ETIMEDOUT;
+	}
+
+	return 0;
+}
+
+static ssize_t als_lux0_input_data_show(struct device *dev,
+			struct device_attribute *attr, char *buf)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct als_data *data = i2c_get_clientdata(client);
+	int ret_val;
+	int temp;
+
+	/* Protect against parallel reads */
+	pm_runtime_get_sync(dev);
+	mutex_lock(&data->mutex);
+
+	/* clear EOC interrupt status */
+	i2c_smbus_write_byte(client, 0x40);
+	/* start measurement */
+	temp = i2c_smbus_read_byte_data(client, 0x81);
+	i2c_smbus_write_byte_data(client, 0x81, temp | 0x08);
+
+	ret_val = als_wait_for_data_ready(dev);
+	if (ret_val < 0)
+		goto failed;
+
+	temp = i2c_smbus_read_byte_data(client, 0x8C); /* LSB data */
+	if (temp < 0) {
+		ret_val = temp;
+		goto failed;
+	}
+	ret_val = i2c_smbus_read_byte_data(client, 0x8D); /* MSB data */
+	if (ret_val < 0)
+		goto failed;
+
+	mutex_unlock(&data->mutex);
+	pm_runtime_put_sync(dev);
+
+	temp = (ret_val << 8) | temp;
+	return sprintf(buf, "%d\n", temp);
+failed:
+	mutex_unlock(&data->mutex);
+	pm_runtime_put_sync(dev);
+	return ret_val;
+}
+
+static ssize_t als_sensing_range_store(struct device *dev,
+		struct device_attribute *attr, const  char *buf, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct als_data *data = i2c_get_clientdata(client);
+	int ret_val;
+	unsigned long val;
+
+	ret_val = kstrtoul(buf, 10, &val);
+	if (ret_val)
+		return ret_val;
+
+	if (val < 4096)
+		val = 1;
+	else if (val < 65536)
+		val = 2;
+	else
+		return -ERANGE;
+
+	pm_runtime_get_sync(dev);
+
+	/* Make sure nobody else reads/modifies/writes 0x81 while we
+	   are active */
+	mutex_lock(&data->mutex);
+
+	ret_val = i2c_smbus_read_byte_data(client, 0x81);
+	if (ret_val < 0)
+		goto fail;
+
+	/* Reset the bits before setting them */
+	ret_val = ret_val & 0xFA;
+
+	if (val == 1) /* Setting detection range up to 4k LUX */
+		ret_val = (ret_val | 0x01);
+	else /* Setting detection range up to 64k LUX*/
+		ret_val = (ret_val | 0x00);
+
+	ret_val = i2c_smbus_write_byte_data(client, 0x81, ret_val);
+
+	if (ret_val >= 0) {
+		/* All OK */
+		mutex_unlock(&data->mutex);
+		pm_runtime_put_sync(dev);
+		return count;
+	}
+fail:
+	mutex_unlock(&data->mutex);
+	pm_runtime_put_sync(dev);
+	return ret_val;
+}
+
+static int als_set_power_state(struct i2c_client *client, bool on_off)
+{
+	int ret_val;
+	struct als_data *data = i2c_get_clientdata(client);
+
+	mutex_lock(&data->mutex);
+	ret_val = i2c_smbus_read_byte_data(client, 0x80);
+	if (ret_val < 0)
+		goto fail;
+	if (on_off)
+		ret_val = ret_val | 0x01;
+	else
+		ret_val = ret_val & 0xFE;
+	ret_val = i2c_smbus_write_byte_data(client, 0x80, ret_val);
+fail:
+	mutex_unlock(&data->mutex);
+	return ret_val;
+}
+
+static DEVICE_ATTR(lux0_sensor_range, S_IRUGO | S_IWUSR,
+	als_sensing_range_show, als_sensing_range_store);
+static DEVICE_ATTR(lux0_input, S_IRUGO, als_lux0_input_data_show, NULL);
+
+static struct attribute *mid_att_als[] = {
+	&dev_attr_lux0_sensor_range.attr,
+	&dev_attr_lux0_input.attr,
+	NULL
+};
+
+static const struct attribute_group m_als_gr = {
+	.name = "apds9802als",
+	.attrs = mid_att_als
+};
+
+static int als_set_default_config(struct i2c_client *client)
+{
+	int ret_val;
+	/* Write the command and then switch on */
+	ret_val = i2c_smbus_write_byte_data(client, 0x80, 0x01);
+	if (ret_val < 0) {
+		dev_err(&client->dev, "failed default switch on write\n");
+		return ret_val;
+	}
+	/* detection range: 1~64K Lux, maunal measurement */
+	ret_val = i2c_smbus_write_byte_data(client, 0x81, 0x08);
+	if (ret_val < 0)
+		dev_err(&client->dev, "failed default LUX on write\n");
+
+	/*  We always get 0 for the 1st measurement after system power on,
+	 *  so make sure it is finished before user asks for data.
+	 */
+	als_wait_for_data_ready(&client->dev);
+
+	return ret_val;
+}
+
+static int apds9802als_probe(struct i2c_client *client)
+{
+	int res;
+	struct als_data *data;
+
+	data = kzalloc_obj(struct als_data);
+	if (data == NULL) {
+		dev_err(&client->dev, "Memory allocation failed\n");
+		return -ENOMEM;
+	}
+	i2c_set_clientdata(client, data);
+	res = sysfs_create_group(&client->dev.kobj, &m_als_gr);
+	if (res) {
+		dev_err(&client->dev, "device create file failed\n");
+		goto als_error1;
+	}
+	dev_info(&client->dev, "ALS chip found\n");
+	als_set_default_config(client);
+	mutex_init(&data->mutex);
+
+	pm_runtime_set_active(&client->dev);
+	pm_runtime_enable(&client->dev);
+
+	return res;
+als_error1:
+	kfree(data);
+	return res;
+}
+
+static void apds9802als_remove(struct i2c_client *client)
+{
+	struct als_data *data = i2c_get_clientdata(client);
+
+	pm_runtime_get_sync(&client->dev);
+
+	als_set_power_state(client, false);
+	sysfs_remove_group(&client->dev.kobj, &m_als_gr);
+
+	pm_runtime_disable(&client->dev);
+	pm_runtime_set_suspended(&client->dev);
+	pm_runtime_put_noidle(&client->dev);
+
+	kfree(data);
+}
+
+#ifdef CONFIG_PM
+
+static int apds9802als_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+
+	als_set_power_state(client, false);
+	return 0;
+}
+
+static int apds9802als_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+
+	als_set_power_state(client, true);
+	return 0;
+}
+
+static UNIVERSAL_DEV_PM_OPS(apds9802als_pm_ops, apds9802als_suspend,
+	apds9802als_resume, NULL);
+
+#define APDS9802ALS_PM_OPS (&apds9802als_pm_ops)
+
+#else	/* CONFIG_PM */
+#define APDS9802ALS_PM_OPS NULL
+#endif	/* CONFIG_PM */
+
+static const struct i2c_device_id apds9802als_id[] = {
+	{ .name = DRIVER_NAME },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(i2c, apds9802als_id);
+
+static struct i2c_driver apds9802als_driver = {
+	.driver = {
+		.name = DRIVER_NAME,
+		.pm = APDS9802ALS_PM_OPS,
+	},
+	.probe = apds9802als_probe,
+	.remove = apds9802als_remove,
+	.id_table = apds9802als_id,
+};
+
+module_i2c_driver(apds9802als_driver);
+
+MODULE_AUTHOR("Anantha Narayanan <Anantha.Narayanan@intel.com");
+MODULE_DESCRIPTION("Avago apds9802als ALS Driver");
+MODULE_LICENSE("GPL v2");