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, 217 insertions, 0 deletions

diff --git a/drivers/extcon/extcon-intel-int3496.c b/drivers/extcon/extcon-intel-int3496.c
new file mode 100644
index 000000000..7d16d5b7d
--- /dev/null
+++ b/drivers/extcon/extcon-intel-int3496.c
@@ -0,0 +1,217 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Intel INT3496 ACPI device extcon driver
+ *
+ * Copyright (c) 2016 Hans de Goede <hdegoede@redhat.com>
+ *
+ * Based on android x86 kernel code which is:
+ *
+ * Copyright (c) 2014, Intel Corporation.
+ * Author: David Cohen <david.a.cohen@linux.intel.com>
+ */
+
+#include <linux/acpi.h>
+#include <linux/devm-helpers.h>
+#include <linux/extcon-provider.h>
+#include <linux/gpio/consumer.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+
+#define INT3496_GPIO_USB_ID	0
+#define INT3496_GPIO_VBUS_EN	1
+#define INT3496_GPIO_USB_MUX	2
+#define DEBOUNCE_TIME		msecs_to_jiffies(50)
+
+struct int3496_data {
+	struct device *dev;
+	struct extcon_dev *edev;
+	struct delayed_work work;
+	struct gpio_desc *gpio_usb_id;
+	struct gpio_desc *gpio_vbus_en;
+	struct gpio_desc *gpio_usb_mux;
+	struct regulator *vbus_boost;
+	int usb_id_irq;
+	bool vbus_boost_enabled;
+};
+
+static const unsigned int int3496_cable[] = {
+	EXTCON_USB_HOST,
+	EXTCON_NONE,
+};
+
+static const struct acpi_gpio_params id_gpios = { INT3496_GPIO_USB_ID, 0, false };
+static const struct acpi_gpio_params vbus_gpios = { INT3496_GPIO_VBUS_EN, 0, false };
+static const struct acpi_gpio_params mux_gpios = { INT3496_GPIO_USB_MUX, 0, false };
+
+static const struct acpi_gpio_mapping acpi_int3496_default_gpios[] = {
+	/*
+	 * Some platforms have a bug in ACPI GPIO description making IRQ
+	 * GPIO to be output only. Ask the GPIO core to ignore this limit.
+	 */
+	{ "id-gpios", &id_gpios, 1, ACPI_GPIO_QUIRK_NO_IO_RESTRICTION },
+	{ "vbus-gpios", &vbus_gpios, 1 },
+	{ "mux-gpios", &mux_gpios, 1 },
+	{ },
+};
+
+static void int3496_set_vbus_boost(struct int3496_data *data, bool enable)
+{
+	int ret;
+
+	if (IS_ERR_OR_NULL(data->vbus_boost))
+		return;
+
+	if (data->vbus_boost_enabled == enable)
+		return;
+
+	if (enable)
+		ret = regulator_enable(data->vbus_boost);
+	else
+		ret = regulator_disable(data->vbus_boost);
+
+	if (ret == 0)
+		data->vbus_boost_enabled = enable;
+	else
+		dev_err(data->dev, "Error updating Vbus boost regulator: %d\n", ret);
+}
+
+static void int3496_do_usb_id(struct work_struct *work)
+{
+	struct int3496_data *data =
+		container_of(work, struct int3496_data, work.work);
+	int id = gpiod_get_value_cansleep(data->gpio_usb_id);
+
+	/* id == 1: PERIPHERAL, id == 0: HOST */
+	dev_dbg(data->dev, "Connected %s cable\n", id ? "PERIPHERAL" : "HOST");
+
+	/*
+	 * Peripheral: set USB mux to peripheral and disable VBUS
+	 * Host: set USB mux to host and enable VBUS
+	 */
+	if (!IS_ERR(data->gpio_usb_mux))
+		gpiod_direction_output(data->gpio_usb_mux, id);
+
+	if (!IS_ERR(data->gpio_vbus_en))
+		gpiod_direction_output(data->gpio_vbus_en, !id);
+	else
+		int3496_set_vbus_boost(data, !id);
+
+	extcon_set_state_sync(data->edev, EXTCON_USB_HOST, !id);
+}
+
+static irqreturn_t int3496_thread_isr(int irq, void *priv)
+{
+	struct int3496_data *data = priv;
+
+	/* Let the pin settle before processing it */
+	mod_delayed_work(system_percpu_wq, &data->work, DEBOUNCE_TIME);
+
+	return IRQ_HANDLED;
+}
+
+static int int3496_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct int3496_data *data;
+	int ret;
+
+	if (has_acpi_companion(dev)) {
+		ret = devm_acpi_dev_add_driver_gpios(dev, acpi_int3496_default_gpios);
+		if (ret) {
+			dev_err(dev, "can't add GPIO ACPI mapping\n");
+			return ret;
+		}
+	}
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->dev = dev;
+	ret = devm_delayed_work_autocancel(dev, &data->work, int3496_do_usb_id);
+	if (ret)
+		return ret;
+
+	data->gpio_usb_id =
+		devm_gpiod_get(dev, "id", GPIOD_IN | GPIOD_FLAGS_BIT_NONEXCLUSIVE);
+	if (IS_ERR(data->gpio_usb_id)) {
+		ret = PTR_ERR(data->gpio_usb_id);
+		dev_err(dev, "can't request USB ID GPIO: %d\n", ret);
+		return ret;
+	}
+
+	data->usb_id_irq = gpiod_to_irq(data->gpio_usb_id);
+	if (data->usb_id_irq < 0) {
+		dev_err(dev, "can't get USB ID IRQ: %d\n", data->usb_id_irq);
+		return data->usb_id_irq;
+	}
+
+	data->gpio_vbus_en = devm_gpiod_get(dev, "vbus", GPIOD_ASIS);
+	if (IS_ERR(data->gpio_vbus_en)) {
+		dev_dbg(dev, "can't request VBUS EN GPIO\n");
+		data->vbus_boost = devm_regulator_get_optional(dev, "vbus");
+	}
+
+	data->gpio_usb_mux = devm_gpiod_get(dev, "mux", GPIOD_ASIS);
+	if (IS_ERR(data->gpio_usb_mux))
+		dev_dbg(dev, "can't request USB MUX GPIO\n");
+
+	/* register extcon device */
+	data->edev = devm_extcon_dev_allocate(dev, int3496_cable);
+	if (IS_ERR(data->edev))
+		return -ENOMEM;
+
+	ret = devm_extcon_dev_register(dev, data->edev);
+	if (ret < 0) {
+		dev_err(dev, "can't register extcon device: %d\n", ret);
+		return ret;
+	}
+
+	ret = devm_request_threaded_irq(dev, data->usb_id_irq,
+					NULL, int3496_thread_isr,
+					IRQF_SHARED | IRQF_ONESHOT |
+					IRQF_TRIGGER_RISING |
+					IRQF_TRIGGER_FALLING,
+					dev_name(dev), data);
+	if (ret < 0) {
+		dev_err(dev, "can't request IRQ for USB ID GPIO: %d\n", ret);
+		return ret;
+	}
+
+	/* process id-pin so that we start with the right status */
+	queue_delayed_work(system_percpu_wq, &data->work, 0);
+	flush_delayed_work(&data->work);
+
+	platform_set_drvdata(pdev, data);
+
+	return 0;
+}
+
+static const struct acpi_device_id int3496_acpi_match[] = {
+	{ "INT3496" },
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, int3496_acpi_match);
+
+static const struct platform_device_id int3496_ids[] = {
+	{ .name = "intel-int3496" },
+	{},
+};
+MODULE_DEVICE_TABLE(platform, int3496_ids);
+
+static struct platform_driver int3496_driver = {
+	.driver = {
+		.name = "intel-int3496",
+		.acpi_match_table = int3496_acpi_match,
+	},
+	.probe = int3496_probe,
+	.id_table = int3496_ids,
+};
+
+module_platform_driver(int3496_driver);
+
+MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
+MODULE_DESCRIPTION("Intel INT3496 ACPI device extcon driver");
+MODULE_LICENSE("GPL v2");