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, 144 insertions, 0 deletions

diff --git a/drivers/hwmon/ad7314.c b/drivers/hwmon/ad7314.c
new file mode 100644
index 000000000..59424103f
--- /dev/null
+++ b/drivers/hwmon/ad7314.c
@@ -0,0 +1,144 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * AD7314 digital temperature sensor driver for AD7314, ADT7301 and ADT7302
+ *
+ * Copyright 2010 Analog Devices Inc.
+ *
+ * Conversion to hwmon from IIO done by Jonathan Cameron <jic23@cam.ac.uk>
+ */
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <linux/spi/spi.h>
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/bitops.h>
+
+/*
+ * AD7314 temperature masks
+ */
+#define AD7314_TEMP_MASK		0x7FE0
+#define AD7314_TEMP_SHIFT		5
+#define AD7314_LEADING_ZEROS_MASK	BIT(15)
+
+/*
+ * ADT7301 and ADT7302 temperature masks
+ */
+#define ADT7301_TEMP_MASK		0x3FFF
+#define ADT7301_LEADING_ZEROS_MASK	(BIT(15) | BIT(14))
+
+enum ad7314_variant {
+	adt7301,
+	adt7302,
+	ad7314,
+};
+
+struct ad7314_data {
+	struct spi_device	*spi_dev;
+	u16 rx ____cacheline_aligned;
+};
+
+static int ad7314_spi_read(struct ad7314_data *chip)
+{
+	int ret;
+
+	ret = spi_read(chip->spi_dev, (u8 *)&chip->rx, sizeof(chip->rx));
+	if (ret < 0) {
+		dev_err(&chip->spi_dev->dev, "SPI read error\n");
+		return ret;
+	}
+
+	return be16_to_cpu(chip->rx);
+}
+
+static ssize_t ad7314_temperature_show(struct device *dev,
+				       struct device_attribute *attr,
+				       char *buf)
+{
+	struct ad7314_data *chip = dev_get_drvdata(dev);
+	s16 data;
+	int ret;
+
+	ret = ad7314_spi_read(chip);
+	if (ret < 0)
+		return ret;
+	switch (spi_get_device_id(chip->spi_dev)->driver_data) {
+	case ad7314:
+		if (ret & AD7314_LEADING_ZEROS_MASK) {
+			/* Invalid read-out, leading zero part is missing */
+			return -EIO;
+		}
+		data = (ret & AD7314_TEMP_MASK) >> AD7314_TEMP_SHIFT;
+		data = sign_extend32(data, 9);
+
+		return sprintf(buf, "%d\n", 250 * data);
+	case adt7301:
+	case adt7302:
+		if (ret & ADT7301_LEADING_ZEROS_MASK) {
+			/* Invalid read-out, leading zero part is missing */
+			return -EIO;
+		}
+		/*
+		 * Documented as a 13 bit twos complement register
+		 * with a sign bit - which is a 14 bit 2's complement
+		 * register.  1lsb - 31.25 milli degrees centigrade
+		 */
+		data = ret & ADT7301_TEMP_MASK;
+		data = sign_extend32(data, 13);
+
+		return sprintf(buf, "%d\n",
+			       DIV_ROUND_CLOSEST(data * 3125, 100));
+	default:
+		return -EINVAL;
+	}
+}
+
+static SENSOR_DEVICE_ATTR_RO(temp1_input, ad7314_temperature, 0);
+
+static struct attribute *ad7314_attrs[] = {
+	&sensor_dev_attr_temp1_input.dev_attr.attr,
+	NULL,
+};
+
+ATTRIBUTE_GROUPS(ad7314);
+
+static int ad7314_probe(struct spi_device *spi_dev)
+{
+	struct ad7314_data *chip;
+	struct device *hwmon_dev;
+
+	chip = devm_kzalloc(&spi_dev->dev, sizeof(*chip), GFP_KERNEL);
+	if (chip == NULL)
+		return -ENOMEM;
+
+	chip->spi_dev = spi_dev;
+	hwmon_dev = devm_hwmon_device_register_with_groups(&spi_dev->dev,
+							   spi_dev->modalias,
+							   chip, ad7314_groups);
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct spi_device_id ad7314_id[] = {
+	{ "adt7301", adt7301 },
+	{ "adt7302", adt7302 },
+	{ "ad7314", ad7314 },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, ad7314_id);
+
+static struct spi_driver ad7314_driver = {
+	.driver = {
+		.name = "ad7314",
+	},
+	.probe = ad7314_probe,
+	.id_table = ad7314_id,
+};
+
+module_spi_driver(ad7314_driver);
+
+MODULE_AUTHOR("Sonic Zhang <sonic.zhang@analog.com>");
+MODULE_DESCRIPTION("Analog Devices AD7314, ADT7301 and ADT7302 digital temperature sensor driver");
+MODULE_LICENSE("GPL v2");