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, 199 insertions, 0 deletions

diff --git a/drivers/input/misc/gpio-vibra.c b/drivers/input/misc/gpio-vibra.c
new file mode 100644
index 000000000..ad44b4d18
--- /dev/null
+++ b/drivers/input/misc/gpio-vibra.c
@@ -0,0 +1,199 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ *  GPIO vibrator driver
+ *
+ *  Copyright (C) 2019 Luca Weiss <luca@z3ntu.xyz>
+ *
+ *  Based on PWM vibrator driver:
+ *  Copyright (C) 2017 Collabora Ltd.
+ *
+ *  Based on previous work from:
+ *  Copyright (C) 2012 Dmitry Torokhov <dmitry.torokhov@gmail.com>
+ *
+ *  Based on PWM beeper driver:
+ *  Copyright (C) 2010, Lars-Peter Clausen <lars@metafoo.de>
+ */
+
+#include <linux/gpio/consumer.h>
+#include <linux/input.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+
+struct gpio_vibrator {
+	struct input_dev *input;
+	struct gpio_desc *gpio;
+	struct regulator *vcc;
+
+	struct work_struct play_work;
+	bool running;
+	bool vcc_on;
+};
+
+static int gpio_vibrator_start(struct gpio_vibrator *vibrator)
+{
+	struct device *pdev = vibrator->input->dev.parent;
+	int err;
+
+	if (!vibrator->vcc_on) {
+		err = regulator_enable(vibrator->vcc);
+		if (err) {
+			dev_err(pdev, "failed to enable regulator: %d\n", err);
+			return err;
+		}
+		vibrator->vcc_on = true;
+	}
+
+	gpiod_set_value_cansleep(vibrator->gpio, 1);
+
+	return 0;
+}
+
+static void gpio_vibrator_stop(struct gpio_vibrator *vibrator)
+{
+	gpiod_set_value_cansleep(vibrator->gpio, 0);
+
+	if (vibrator->vcc_on) {
+		regulator_disable(vibrator->vcc);
+		vibrator->vcc_on = false;
+	}
+}
+
+static void gpio_vibrator_play_work(struct work_struct *work)
+{
+	struct gpio_vibrator *vibrator =
+		container_of(work, struct gpio_vibrator, play_work);
+
+	if (vibrator->running)
+		gpio_vibrator_start(vibrator);
+	else
+		gpio_vibrator_stop(vibrator);
+}
+
+static int gpio_vibrator_play_effect(struct input_dev *dev, void *data,
+				     struct ff_effect *effect)
+{
+	struct gpio_vibrator *vibrator = input_get_drvdata(dev);
+	int level;
+
+	level = effect->u.rumble.strong_magnitude;
+	if (!level)
+		level = effect->u.rumble.weak_magnitude;
+
+	vibrator->running = level;
+	schedule_work(&vibrator->play_work);
+
+	return 0;
+}
+
+static void gpio_vibrator_close(struct input_dev *input)
+{
+	struct gpio_vibrator *vibrator = input_get_drvdata(input);
+
+	cancel_work_sync(&vibrator->play_work);
+	gpio_vibrator_stop(vibrator);
+	vibrator->running = false;
+}
+
+static int gpio_vibrator_probe(struct platform_device *pdev)
+{
+	struct gpio_vibrator *vibrator;
+	int err;
+
+	vibrator = devm_kzalloc(&pdev->dev, sizeof(*vibrator), GFP_KERNEL);
+	if (!vibrator)
+		return -ENOMEM;
+
+	vibrator->input = devm_input_allocate_device(&pdev->dev);
+	if (!vibrator->input)
+		return -ENOMEM;
+
+	vibrator->vcc = devm_regulator_get(&pdev->dev, "vcc");
+	if (IS_ERR(vibrator->vcc))
+		return dev_err_probe(&pdev->dev, PTR_ERR(vibrator->vcc),
+				     "Failed to request regulator\n");
+
+	vibrator->gpio = devm_gpiod_get(&pdev->dev, "enable", GPIOD_OUT_LOW);
+	if (IS_ERR(vibrator->gpio))
+		return dev_err_probe(&pdev->dev, PTR_ERR(vibrator->gpio),
+				     "Failed to request main gpio\n");
+
+	INIT_WORK(&vibrator->play_work, gpio_vibrator_play_work);
+
+	vibrator->input->name = "gpio-vibrator";
+	vibrator->input->id.bustype = BUS_HOST;
+	vibrator->input->close = gpio_vibrator_close;
+
+	input_set_drvdata(vibrator->input, vibrator);
+	input_set_capability(vibrator->input, EV_FF, FF_RUMBLE);
+
+	err = input_ff_create_memless(vibrator->input, NULL,
+				      gpio_vibrator_play_effect);
+	if (err) {
+		dev_err(&pdev->dev, "Couldn't create FF dev: %d\n", err);
+		return err;
+	}
+
+	err = input_register_device(vibrator->input);
+	if (err) {
+		dev_err(&pdev->dev, "Couldn't register input dev: %d\n", err);
+		return err;
+	}
+
+	platform_set_drvdata(pdev, vibrator);
+
+	return 0;
+}
+
+static int gpio_vibrator_suspend(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct gpio_vibrator *vibrator = platform_get_drvdata(pdev);
+
+	cancel_work_sync(&vibrator->play_work);
+	if (vibrator->running)
+		gpio_vibrator_stop(vibrator);
+
+	return 0;
+}
+
+static int gpio_vibrator_resume(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct gpio_vibrator *vibrator = platform_get_drvdata(pdev);
+
+	if (vibrator->running)
+		gpio_vibrator_start(vibrator);
+
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(gpio_vibrator_pm_ops,
+				gpio_vibrator_suspend, gpio_vibrator_resume);
+
+#ifdef CONFIG_OF
+static const struct of_device_id gpio_vibra_dt_match_table[] = {
+	{ .compatible = "gpio-vibrator" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, gpio_vibra_dt_match_table);
+#endif
+
+static struct platform_driver gpio_vibrator_driver = {
+	.probe	= gpio_vibrator_probe,
+	.driver	= {
+		.name	= "gpio-vibrator",
+		.pm	= pm_sleep_ptr(&gpio_vibrator_pm_ops),
+		.of_match_table = of_match_ptr(gpio_vibra_dt_match_table),
+	},
+};
+module_platform_driver(gpio_vibrator_driver);
+
+MODULE_AUTHOR("Luca Weiss <luca@z3ntu.xy>");
+MODULE_DESCRIPTION("GPIO vibrator driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:gpio-vibrator");