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, 294 insertions, 0 deletions

diff --git a/drivers/extcon/extcon-usb-gpio.c b/drivers/extcon/extcon-usb-gpio.c
new file mode 100644
index 000000000..e35fd1f69
--- /dev/null
+++ b/drivers/extcon/extcon-usb-gpio.c
@@ -0,0 +1,294 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * drivers/extcon/extcon-usb-gpio.c - USB GPIO extcon driver
+ *
+ * Copyright (C) 2015 Texas Instruments Incorporated - https://www.ti.com
+ * Author: Roger Quadros <rogerq@ti.com>
+ */
+
+#include <linux/extcon-provider.h>
+#include <linux/gpio/consumer.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+#include <linux/pinctrl/consumer.h>
+
+#define USB_GPIO_DEBOUNCE_MS	20	/* ms */
+
+struct usb_extcon_info {
+	struct device *dev;
+	struct extcon_dev *edev;
+
+	struct gpio_desc *id_gpiod;
+	struct gpio_desc *vbus_gpiod;
+	int id_irq;
+	int vbus_irq;
+
+	unsigned long debounce_jiffies;
+	struct delayed_work wq_detcable;
+};
+
+static const unsigned int usb_extcon_cable[] = {
+	EXTCON_USB,
+	EXTCON_USB_HOST,
+	EXTCON_NONE,
+};
+
+/*
+ * "USB" = VBUS and "USB-HOST" = !ID, so we have:
+ * Both "USB" and "USB-HOST" can't be set as active at the
+ * same time so if "USB-HOST" is active (i.e. ID is 0)  we keep "USB" inactive
+ * even if VBUS is on.
+ *
+ *  State              |    ID   |   VBUS
+ * ----------------------------------------
+ *  [1] USB            |    H    |    H
+ *  [2] none           |    H    |    L
+ *  [3] USB-HOST       |    L    |    H
+ *  [4] USB-HOST       |    L    |    L
+ *
+ * In case we have only one of these signals:
+ * - VBUS only - we want to distinguish between [1] and [2], so ID is always 1.
+ * - ID only - we want to distinguish between [1] and [4], so VBUS = ID.
+*/
+static void usb_extcon_detect_cable(struct work_struct *work)
+{
+	int id, vbus;
+	struct usb_extcon_info *info = container_of(to_delayed_work(work),
+						    struct usb_extcon_info,
+						    wq_detcable);
+
+	/* check ID and VBUS and update cable state */
+	id = info->id_gpiod ?
+		gpiod_get_value_cansleep(info->id_gpiod) : 1;
+	vbus = info->vbus_gpiod ?
+		gpiod_get_value_cansleep(info->vbus_gpiod) : id;
+
+	/* at first we clean states which are no longer active */
+	if (id)
+		extcon_set_state_sync(info->edev, EXTCON_USB_HOST, false);
+	if (!vbus)
+		extcon_set_state_sync(info->edev, EXTCON_USB, false);
+
+	if (!id) {
+		extcon_set_state_sync(info->edev, EXTCON_USB_HOST, true);
+	} else {
+		if (vbus)
+			extcon_set_state_sync(info->edev, EXTCON_USB, true);
+	}
+}
+
+static irqreturn_t usb_irq_handler(int irq, void *dev_id)
+{
+	struct usb_extcon_info *info = dev_id;
+
+	queue_delayed_work(system_power_efficient_wq, &info->wq_detcable,
+			   info->debounce_jiffies);
+
+	return IRQ_HANDLED;
+}
+
+static int usb_extcon_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	struct usb_extcon_info *info;
+	int ret;
+
+	if (!np)
+		return -EINVAL;
+
+	info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	info->dev = dev;
+	info->id_gpiod = devm_gpiod_get_optional(&pdev->dev, "id", GPIOD_IN);
+	info->vbus_gpiod = devm_gpiod_get_optional(&pdev->dev, "vbus",
+						   GPIOD_IN);
+
+	if (!info->id_gpiod && !info->vbus_gpiod) {
+		dev_err(dev, "failed to get gpios\n");
+		return -ENODEV;
+	}
+
+	if (IS_ERR(info->id_gpiod))
+		return PTR_ERR(info->id_gpiod);
+
+	if (IS_ERR(info->vbus_gpiod))
+		return PTR_ERR(info->vbus_gpiod);
+
+	info->edev = devm_extcon_dev_allocate(dev, usb_extcon_cable);
+	if (IS_ERR(info->edev)) {
+		dev_err(dev, "failed to allocate extcon device\n");
+		return -ENOMEM;
+	}
+
+	ret = devm_extcon_dev_register(dev, info->edev);
+	if (ret < 0) {
+		dev_err(dev, "failed to register extcon device\n");
+		return ret;
+	}
+
+	if (info->id_gpiod)
+		ret = gpiod_set_debounce(info->id_gpiod,
+					 USB_GPIO_DEBOUNCE_MS * 1000);
+	if (!ret && info->vbus_gpiod)
+		ret = gpiod_set_debounce(info->vbus_gpiod,
+					 USB_GPIO_DEBOUNCE_MS * 1000);
+
+	if (ret < 0)
+		info->debounce_jiffies = msecs_to_jiffies(USB_GPIO_DEBOUNCE_MS);
+
+	INIT_DELAYED_WORK(&info->wq_detcable, usb_extcon_detect_cable);
+
+	if (info->id_gpiod) {
+		info->id_irq = gpiod_to_irq(info->id_gpiod);
+		if (info->id_irq < 0) {
+			dev_err(dev, "failed to get ID IRQ\n");
+			return info->id_irq;
+		}
+
+		ret = devm_request_threaded_irq(dev, info->id_irq, NULL,
+						usb_irq_handler,
+						IRQF_TRIGGER_RISING |
+						IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+						pdev->name, info);
+		if (ret < 0) {
+			dev_err(dev, "failed to request handler for ID IRQ\n");
+			return ret;
+		}
+	}
+
+	if (info->vbus_gpiod) {
+		info->vbus_irq = gpiod_to_irq(info->vbus_gpiod);
+		if (info->vbus_irq < 0) {
+			dev_err(dev, "failed to get VBUS IRQ\n");
+			return info->vbus_irq;
+		}
+
+		ret = devm_request_threaded_irq(dev, info->vbus_irq, NULL,
+						usb_irq_handler,
+						IRQF_TRIGGER_RISING |
+						IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+						pdev->name, info);
+		if (ret < 0) {
+			dev_err(dev, "failed to request handler for VBUS IRQ\n");
+			return ret;
+		}
+	}
+
+	platform_set_drvdata(pdev, info);
+	device_set_wakeup_capable(&pdev->dev, true);
+
+	/* Perform initial detection */
+	usb_extcon_detect_cable(&info->wq_detcable.work);
+
+	return 0;
+}
+
+static void usb_extcon_remove(struct platform_device *pdev)
+{
+	struct usb_extcon_info *info = platform_get_drvdata(pdev);
+
+	cancel_delayed_work_sync(&info->wq_detcable);
+	device_init_wakeup(&pdev->dev, false);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int usb_extcon_suspend(struct device *dev)
+{
+	struct usb_extcon_info *info = dev_get_drvdata(dev);
+	int ret = 0;
+
+	if (device_may_wakeup(dev)) {
+		if (info->id_gpiod) {
+			ret = enable_irq_wake(info->id_irq);
+			if (ret)
+				return ret;
+		}
+		if (info->vbus_gpiod) {
+			ret = enable_irq_wake(info->vbus_irq);
+			if (ret) {
+				if (info->id_gpiod)
+					disable_irq_wake(info->id_irq);
+
+				return ret;
+			}
+		}
+	}
+
+	if (!device_may_wakeup(dev))
+		pinctrl_pm_select_sleep_state(dev);
+
+	return ret;
+}
+
+static int usb_extcon_resume(struct device *dev)
+{
+	struct usb_extcon_info *info = dev_get_drvdata(dev);
+	int ret = 0;
+
+	if (!device_may_wakeup(dev))
+		pinctrl_pm_select_default_state(dev);
+
+	if (device_may_wakeup(dev)) {
+		if (info->id_gpiod) {
+			ret = disable_irq_wake(info->id_irq);
+			if (ret)
+				return ret;
+		}
+		if (info->vbus_gpiod) {
+			ret = disable_irq_wake(info->vbus_irq);
+			if (ret) {
+				if (info->id_gpiod)
+					enable_irq_wake(info->id_irq);
+
+				return ret;
+			}
+		}
+	}
+
+	queue_delayed_work(system_power_efficient_wq,
+			   &info->wq_detcable, 0);
+
+	return ret;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(usb_extcon_pm_ops,
+			 usb_extcon_suspend, usb_extcon_resume);
+
+static const struct of_device_id usb_extcon_dt_match[] = {
+	{ .compatible = "linux,extcon-usb-gpio", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, usb_extcon_dt_match);
+
+static const struct platform_device_id usb_extcon_platform_ids[] = {
+	{ .name = "extcon-usb-gpio", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(platform, usb_extcon_platform_ids);
+
+static struct platform_driver usb_extcon_driver = {
+	.probe		= usb_extcon_probe,
+	.remove		= usb_extcon_remove,
+	.driver		= {
+		.name	= "extcon-usb-gpio",
+		.pm	= &usb_extcon_pm_ops,
+		.of_match_table = usb_extcon_dt_match,
+	},
+	.id_table = usb_extcon_platform_ids,
+};
+
+module_platform_driver(usb_extcon_driver);
+
+MODULE_AUTHOR("Roger Quadros <rogerq@ti.com>");
+MODULE_DESCRIPTION("USB GPIO extcon driver");
+MODULE_LICENSE("GPL v2");