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, 307 insertions, 0 deletions

diff --git a/drivers/input/keyboard/max7360-keypad.c b/drivers/input/keyboard/max7360-keypad.c
new file mode 100644
index 000000000..1e5251f87
--- /dev/null
+++ b/drivers/input/keyboard/max7360-keypad.c
@@ -0,0 +1,307 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2025 Bootlin
+ *
+ * Author: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bitops.h>
+#include <linux/dev_printk.h>
+#include <linux/device/devres.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/input.h>
+#include <linux/input/matrix_keypad.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/max7360.h>
+#include <linux/minmax.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/platform_device.h>
+#include <linux/pm_wakeirq.h>
+#include <linux/regmap.h>
+
+struct max7360_keypad {
+	struct input_dev *input;
+	unsigned int rows;
+	unsigned int cols;
+	unsigned int debounce_ms;
+	int irq;
+	struct regmap *regmap;
+	unsigned short keycodes[MAX7360_MAX_KEY_ROWS * MAX7360_MAX_KEY_COLS];
+};
+
+static irqreturn_t max7360_keypad_irq(int irq, void *data)
+{
+	struct max7360_keypad *max7360_keypad = data;
+	struct device *dev = max7360_keypad->input->dev.parent;
+	unsigned int val;
+	unsigned int row, col;
+	unsigned int release;
+	unsigned int code;
+	int error;
+
+	error = regmap_read(max7360_keypad->regmap, MAX7360_REG_KEYFIFO, &val);
+	if (error) {
+		dev_err(dev, "Failed to read MAX7360 FIFO");
+		return IRQ_NONE;
+	}
+
+	/* FIFO overflow: ignore it and get next event. */
+	if (val == MAX7360_FIFO_OVERFLOW) {
+		dev_warn(dev, "max7360 FIFO overflow");
+		error = regmap_read_poll_timeout(max7360_keypad->regmap, MAX7360_REG_KEYFIFO,
+						 val, val != MAX7360_FIFO_OVERFLOW, 0, 1000);
+		if (error) {
+			dev_err(dev, "Failed to empty MAX7360 FIFO");
+			return IRQ_NONE;
+		}
+	}
+
+	if (val == MAX7360_FIFO_EMPTY) {
+		dev_dbg(dev, "Got a spurious interrupt");
+
+		return IRQ_NONE;
+	}
+
+	row = FIELD_GET(MAX7360_FIFO_ROW, val);
+	col = FIELD_GET(MAX7360_FIFO_COL, val);
+	release = val & MAX7360_FIFO_RELEASE;
+
+	code = MATRIX_SCAN_CODE(row, col, get_count_order(max7360_keypad->cols));
+
+	dev_dbg(dev, "key[%d:%d] %s\n", row, col, release ? "release" : "press");
+
+	input_event(max7360_keypad->input, EV_MSC, MSC_SCAN, code);
+	input_report_key(max7360_keypad->input, max7360_keypad->keycodes[code], !release);
+	input_sync(max7360_keypad->input);
+
+	return IRQ_HANDLED;
+}
+
+static int max7360_keypad_open(struct input_dev *pdev)
+{
+	struct max7360_keypad *max7360_keypad = input_get_drvdata(pdev);
+	struct device *dev = max7360_keypad->input->dev.parent;
+	int error;
+
+	/* Somebody is using the device: get out of sleep. */
+	error = regmap_write_bits(max7360_keypad->regmap, MAX7360_REG_CONFIG,
+				  MAX7360_CFG_SLEEP, MAX7360_CFG_SLEEP);
+	if (error)
+		dev_err(dev, "Failed to write max7360 configuration: %d\n", error);
+
+	return error;
+}
+
+static void max7360_keypad_close(struct input_dev *pdev)
+{
+	struct max7360_keypad *max7360_keypad = input_get_drvdata(pdev);
+	struct device *dev = max7360_keypad->input->dev.parent;
+	int error;
+
+	/* Nobody is using the device anymore: go to sleep. */
+	error = regmap_write_bits(max7360_keypad->regmap, MAX7360_REG_CONFIG, MAX7360_CFG_SLEEP, 0);
+	if (error)
+		dev_err(dev, "Failed to write max7360 configuration: %d\n", error);
+}
+
+static int max7360_keypad_hw_init(struct max7360_keypad *max7360_keypad)
+{
+	struct device *dev = max7360_keypad->input->dev.parent;
+	unsigned int val;
+	int error;
+
+	val = max7360_keypad->debounce_ms - MAX7360_DEBOUNCE_MIN;
+	error = regmap_write_bits(max7360_keypad->regmap, MAX7360_REG_DEBOUNCE,
+				  MAX7360_DEBOUNCE,
+				  FIELD_PREP(MAX7360_DEBOUNCE, val));
+	if (error)
+		return dev_err_probe(dev, error,
+				     "Failed to write max7360 debounce configuration\n");
+
+	error = regmap_write_bits(max7360_keypad->regmap, MAX7360_REG_INTERRUPT,
+				  MAX7360_INTERRUPT_TIME_MASK,
+				  FIELD_PREP(MAX7360_INTERRUPT_TIME_MASK, 1));
+	if (error)
+		return dev_err_probe(dev, error,
+				     "Failed to write max7360 keypad interrupt configuration\n");
+
+	return 0;
+}
+
+static int max7360_keypad_build_keymap(struct max7360_keypad *max7360_keypad)
+{
+	struct input_dev *input_dev = max7360_keypad->input;
+	struct device *dev = input_dev->dev.parent->parent;
+	struct matrix_keymap_data keymap_data;
+	const char *propname = "linux,keymap";
+	unsigned int max_keys;
+	int error;
+	int size;
+
+	size = device_property_count_u32(dev, propname);
+	if (size <= 0) {
+		dev_err(dev, "missing or malformed property %s: %d\n", propname, size);
+		return size < 0 ? size : -EINVAL;
+	}
+
+	max_keys = max7360_keypad->cols * max7360_keypad->rows;
+	if (size > max_keys) {
+		dev_err(dev, "%s size overflow (%d vs max %u)\n", propname, size, max_keys);
+		return -EINVAL;
+	}
+
+	u32 *keys __free(kfree) = kmalloc_array(size, sizeof(*keys), GFP_KERNEL);
+	if (!keys)
+		return -ENOMEM;
+
+	error = device_property_read_u32_array(dev, propname, keys, size);
+	if (error) {
+		dev_err(dev, "failed to read %s property: %d\n", propname, error);
+		return error;
+	}
+
+	keymap_data.keymap = keys;
+	keymap_data.keymap_size = size;
+	error = matrix_keypad_build_keymap(&keymap_data, NULL,
+					   max7360_keypad->rows, max7360_keypad->cols,
+					   max7360_keypad->keycodes, max7360_keypad->input);
+	if (error)
+		return error;
+
+	return 0;
+}
+
+static int max7360_keypad_parse_fw(struct device *dev,
+				   struct max7360_keypad *max7360_keypad,
+				   bool *autorepeat)
+{
+	int error;
+
+	error = matrix_keypad_parse_properties(dev->parent, &max7360_keypad->rows,
+					       &max7360_keypad->cols);
+	if (error)
+		return error;
+
+	if (!max7360_keypad->rows || !max7360_keypad->cols ||
+	    max7360_keypad->rows > MAX7360_MAX_KEY_ROWS ||
+	    max7360_keypad->cols > MAX7360_MAX_KEY_COLS) {
+		dev_err(dev, "Invalid number of columns or rows (%ux%u)\n",
+			max7360_keypad->cols, max7360_keypad->rows);
+		return -EINVAL;
+	}
+
+	*autorepeat = device_property_read_bool(dev->parent, "autorepeat");
+
+	max7360_keypad->debounce_ms = MAX7360_DEBOUNCE_MIN;
+	error = device_property_read_u32(dev->parent, "keypad-debounce-delay-ms",
+					 &max7360_keypad->debounce_ms);
+	if (error == -EINVAL) {
+		dev_info(dev, "Using default keypad-debounce-delay-ms: %u\n",
+			 max7360_keypad->debounce_ms);
+	} else if (error < 0) {
+		dev_err(dev, "Failed to read keypad-debounce-delay-ms property\n");
+		return error;
+	}
+
+	if (!in_range(max7360_keypad->debounce_ms, MAX7360_DEBOUNCE_MIN,
+		      MAX7360_DEBOUNCE_MAX - MAX7360_DEBOUNCE_MIN + 1)) {
+		dev_err(dev, "Invalid keypad-debounce-delay-ms: %u, should be between %u and %u.\n",
+			max7360_keypad->debounce_ms, MAX7360_DEBOUNCE_MIN, MAX7360_DEBOUNCE_MAX);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int max7360_keypad_probe(struct platform_device *pdev)
+{
+	struct max7360_keypad *max7360_keypad;
+	struct device *dev = &pdev->dev;
+	struct input_dev *input;
+	struct regmap *regmap;
+	bool autorepeat;
+	int error;
+	int irq;
+
+	regmap = dev_get_regmap(dev->parent, NULL);
+	if (!regmap)
+		return dev_err_probe(dev, -ENODEV, "Could not get parent regmap\n");
+
+	irq = fwnode_irq_get_byname(dev_fwnode(dev->parent), "intk");
+	if (irq < 0)
+		return dev_err_probe(dev, irq, "Failed to get IRQ\n");
+
+	max7360_keypad = devm_kzalloc(dev, sizeof(*max7360_keypad), GFP_KERNEL);
+	if (!max7360_keypad)
+		return -ENOMEM;
+
+	max7360_keypad->regmap = regmap;
+
+	error = max7360_keypad_parse_fw(dev, max7360_keypad, &autorepeat);
+	if (error)
+		return error;
+
+	input = devm_input_allocate_device(dev);
+	if (!input)
+		return -ENOMEM;
+
+	max7360_keypad->input = input;
+
+	input->id.bustype = BUS_I2C;
+	input->name = pdev->name;
+	input->open = max7360_keypad_open;
+	input->close = max7360_keypad_close;
+
+	error = max7360_keypad_build_keymap(max7360_keypad);
+	if (error)
+		return dev_err_probe(dev, error, "Failed to build keymap\n");
+
+	input_set_capability(input, EV_MSC, MSC_SCAN);
+	if (autorepeat)
+		__set_bit(EV_REP, input->evbit);
+
+	input_set_drvdata(input, max7360_keypad);
+
+	error = devm_request_threaded_irq(dev, irq, NULL, max7360_keypad_irq,
+					  IRQF_ONESHOT,
+					  "max7360-keypad", max7360_keypad);
+	if (error)
+		return dev_err_probe(dev, error, "Failed to register interrupt\n");
+
+	error = input_register_device(input);
+	if (error)
+		return dev_err_probe(dev, error, "Could not register input device\n");
+
+	error = max7360_keypad_hw_init(max7360_keypad);
+	if (error)
+		return dev_err_probe(dev, error, "Failed to initialize max7360 keypad\n");
+
+	device_init_wakeup(dev, true);
+	error = dev_pm_set_wake_irq(dev, irq);
+	if (error)
+		dev_warn(dev, "Failed to set up wakeup irq: %d\n", error);
+
+	return 0;
+}
+
+static void max7360_keypad_remove(struct platform_device *pdev)
+{
+	dev_pm_clear_wake_irq(&pdev->dev);
+	device_init_wakeup(&pdev->dev, false);
+}
+
+static struct platform_driver max7360_keypad_driver = {
+	.driver = {
+		.name	= "max7360-keypad",
+	},
+	.probe		= max7360_keypad_probe,
+	.remove		= max7360_keypad_remove,
+};
+module_platform_driver(max7360_keypad_driver);
+
+MODULE_DESCRIPTION("MAX7360 Keypad driver");
+MODULE_AUTHOR("Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>");
+MODULE_LICENSE("GPL");