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, 222 insertions, 0 deletions

diff --git a/drivers/hwmon/tmp103.c b/drivers/hwmon/tmp103.c
new file mode 100644
index 000000000..f13d24767
--- /dev/null
+++ b/drivers/hwmon/tmp103.c
@@ -0,0 +1,222 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Texas Instruments TMP103 SMBus temperature sensor driver
+ * Copyright (C) 2014 Heiko Schocher <hs@denx.de>
+ *
+ * Based on:
+ * Texas Instruments TMP102 SMBus temperature sensor driver
+ *
+ * Copyright (C) 2010 Steven King <sfking@fdwdc.com>
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/hwmon.h>
+#include <linux/err.h>
+#include <linux/device.h>
+#include <linux/regmap.h>
+
+#define TMP103_TEMP_REG		0x00
+#define TMP103_CONF_REG		0x01
+#define TMP103_TLOW_REG		0x02
+#define TMP103_THIGH_REG	0x03
+
+#define TMP103_CONF_M0		0x01
+#define TMP103_CONF_M1		0x02
+#define TMP103_CONF_LC		0x04
+#define TMP103_CONF_FL		0x08
+#define TMP103_CONF_FH		0x10
+#define TMP103_CONF_CR0		0x20
+#define TMP103_CONF_CR1		0x40
+#define TMP103_CONF_ID		0x80
+#define TMP103_CONF_SD		(TMP103_CONF_M1)
+#define TMP103_CONF_SD_MASK	(TMP103_CONF_M0 | TMP103_CONF_M1)
+
+#define TMP103_CONFIG		(TMP103_CONF_CR1 | TMP103_CONF_M1)
+#define TMP103_CONFIG_MASK	(TMP103_CONF_CR0 | TMP103_CONF_CR1 | \
+				 TMP103_CONF_M0 | TMP103_CONF_M1)
+
+static inline int tmp103_reg_to_mc(s8 val)
+{
+	return val * 1000;
+}
+
+static inline u8 tmp103_mc_to_reg(int val)
+{
+	return DIV_ROUND_CLOSEST(val, 1000);
+}
+
+static int tmp103_read(struct device *dev, enum hwmon_sensor_types type,
+		       u32 attr, int channel, long *temp)
+{
+	struct regmap *regmap = dev_get_drvdata(dev);
+	unsigned int regval;
+	int err, reg;
+
+	switch (attr) {
+	case hwmon_temp_input:
+		reg = TMP103_TEMP_REG;
+		break;
+	case hwmon_temp_min:
+		reg = TMP103_TLOW_REG;
+		break;
+	case hwmon_temp_max:
+		reg = TMP103_THIGH_REG;
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	err = regmap_read(regmap, reg, &regval);
+	if (err < 0)
+		return err;
+
+	*temp = tmp103_reg_to_mc(regval);
+
+	return 0;
+}
+
+static int tmp103_write(struct device *dev, enum hwmon_sensor_types type,
+			u32 attr, int channel, long temp)
+{
+	struct regmap *regmap = dev_get_drvdata(dev);
+	int reg;
+
+	switch (attr) {
+	case hwmon_temp_min:
+		reg = TMP103_TLOW_REG;
+		break;
+	case hwmon_temp_max:
+		reg = TMP103_THIGH_REG;
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	temp = clamp_val(temp, -55000, 127000);
+	return regmap_write(regmap, reg, tmp103_mc_to_reg(temp));
+}
+
+static umode_t tmp103_is_visible(const void *data, enum hwmon_sensor_types type,
+				 u32 attr, int channel)
+{
+	if (type != hwmon_temp)
+		return 0;
+
+	switch (attr) {
+	case hwmon_temp_input:
+		return 0444;
+	case hwmon_temp_min:
+	case hwmon_temp_max:
+		return 0644;
+	default:
+		return 0;
+	}
+}
+
+static const struct hwmon_channel_info * const tmp103_info[] = {
+	HWMON_CHANNEL_INFO(chip,
+			   HWMON_C_REGISTER_TZ),
+	HWMON_CHANNEL_INFO(temp,
+			   HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MIN),
+	NULL
+};
+
+static const struct hwmon_ops tmp103_hwmon_ops = {
+	.is_visible = tmp103_is_visible,
+	.read = tmp103_read,
+	.write = tmp103_write,
+};
+
+static const struct hwmon_chip_info tmp103_chip_info = {
+	.ops = &tmp103_hwmon_ops,
+	.info = tmp103_info,
+};
+
+static bool tmp103_regmap_is_volatile(struct device *dev, unsigned int reg)
+{
+	return reg == TMP103_TEMP_REG;
+}
+
+static const struct regmap_config tmp103_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = TMP103_THIGH_REG,
+	.volatile_reg = tmp103_regmap_is_volatile,
+};
+
+static int tmp103_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct device *hwmon_dev;
+	struct regmap *regmap;
+	int ret;
+
+	regmap = devm_regmap_init_i2c(client, &tmp103_regmap_config);
+	if (IS_ERR(regmap)) {
+		dev_err(dev, "failed to allocate register map\n");
+		return PTR_ERR(regmap);
+	}
+
+	ret = regmap_update_bits(regmap, TMP103_CONF_REG, TMP103_CONFIG_MASK,
+				 TMP103_CONFIG);
+	if (ret < 0) {
+		dev_err(&client->dev, "error writing config register\n");
+		return ret;
+	}
+
+	i2c_set_clientdata(client, regmap);
+	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
+							 regmap,
+							 &tmp103_chip_info,
+							 NULL);
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static int tmp103_suspend(struct device *dev)
+{
+	struct regmap *regmap = dev_get_drvdata(dev);
+
+	return regmap_update_bits(regmap, TMP103_CONF_REG,
+				  TMP103_CONF_SD_MASK, 0);
+}
+
+static int tmp103_resume(struct device *dev)
+{
+	struct regmap *regmap = dev_get_drvdata(dev);
+
+	return regmap_update_bits(regmap, TMP103_CONF_REG,
+				  TMP103_CONF_SD_MASK, TMP103_CONF_SD);
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(tmp103_dev_pm_ops, tmp103_suspend, tmp103_resume);
+
+static const struct i2c_device_id tmp103_id[] = {
+	{ .name = "tmp103" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, tmp103_id);
+
+static const struct of_device_id __maybe_unused tmp103_of_match[] = {
+	{ .compatible = "ti,tmp103" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, tmp103_of_match);
+
+static struct i2c_driver tmp103_driver = {
+	.driver = {
+		.name	= "tmp103",
+		.of_match_table = of_match_ptr(tmp103_of_match),
+		.pm	= pm_sleep_ptr(&tmp103_dev_pm_ops),
+	},
+	.probe		= tmp103_probe,
+	.id_table	= tmp103_id,
+};
+
+module_i2c_driver(tmp103_driver);
+
+MODULE_AUTHOR("Heiko Schocher <hs@denx.de>");
+MODULE_DESCRIPTION("Texas Instruments TMP103 temperature sensor driver");
+MODULE_LICENSE("GPL");