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, 213 insertions, 0 deletions

diff --git a/drivers/extcon/extcon-adc-jack.c b/drivers/extcon/extcon-adc-jack.c
new file mode 100644
index 000000000..e735f43dc
--- /dev/null
+++ b/drivers/extcon/extcon-adc-jack.c
@@ -0,0 +1,213 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * drivers/extcon/extcon-adc-jack.c
+ *
+ * Analog Jack extcon driver with ADC-based detection capability.
+ *
+ * Copyright (C) 2016 Samsung Electronics
+ * Chanwoo Choi <cw00.choi@samsung.com>
+ *
+ * Copyright (C) 2012 Samsung Electronics
+ * MyungJoo Ham <myungjoo.ham@samsung.com>
+ *
+ * Modified for calling to IIO to get adc by <anish.singh@samsung.com>
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/workqueue.h>
+#include <linux/iio/consumer.h>
+#include <linux/extcon/extcon-adc-jack.h>
+#include <linux/extcon-provider.h>
+
+/**
+ * struct adc_jack_data - internal data for adc_jack device driver
+ * @dev:		The device structure associated with the adc_jack.
+ * @edev:		extcon device.
+ * @cable_names:	list of supported cables.
+ * @adc_conditions:	list of adc value conditions.
+ * @num_conditions:	size of adc_conditions.
+ * @irq:		irq number of attach/detach event (0 if not exist).
+ * @handling_delay:	interrupt handler will schedule extcon event
+ *			handling at handling_delay jiffies.
+ * @handler:		extcon event handler called by interrupt handler.
+ * @chan:		iio channel being queried.
+ * @wakeup_source:	Indicates if the device can wake up the system.
+ */
+struct adc_jack_data {
+	struct device *dev;
+	struct extcon_dev *edev;
+
+	const unsigned int **cable_names;
+	struct adc_jack_cond *adc_conditions;
+	int num_conditions;
+
+	int irq;
+	unsigned long handling_delay; /* in jiffies */
+	struct delayed_work handler;
+
+	struct iio_channel *chan;
+	bool wakeup_source;
+};
+
+static void adc_jack_handler(struct work_struct *work)
+{
+	struct adc_jack_data *data = container_of(to_delayed_work(work),
+			struct adc_jack_data,
+			handler);
+	struct adc_jack_cond *def;
+	int ret, adc_val;
+	int i;
+
+	ret = iio_read_channel_raw(data->chan, &adc_val);
+	if (ret < 0) {
+		dev_err(data->dev, "read channel() error: %d\n", ret);
+		return;
+	}
+
+	/* Get state from adc value with adc_conditions */
+	for (i = 0; i < data->num_conditions; i++) {
+		def = &data->adc_conditions[i];
+		if (def->min_adc <= adc_val && def->max_adc >= adc_val) {
+			extcon_set_state_sync(data->edev, def->id, true);
+			return;
+		}
+	}
+
+	/* Set the detached state if adc value is not included in the range */
+	for (i = 0; i < data->num_conditions; i++) {
+		def = &data->adc_conditions[i];
+		extcon_set_state_sync(data->edev, def->id, false);
+	}
+}
+
+static irqreturn_t adc_jack_irq_thread(int irq, void *_data)
+{
+	struct adc_jack_data *data = _data;
+
+	queue_delayed_work(system_power_efficient_wq,
+			   &data->handler, data->handling_delay);
+	return IRQ_HANDLED;
+}
+
+static int adc_jack_probe(struct platform_device *pdev)
+{
+	struct adc_jack_data *data;
+	struct adc_jack_pdata *pdata = dev_get_platdata(&pdev->dev);
+	int i, err = 0;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	if (!pdata->cable_names) {
+		dev_err(&pdev->dev, "error: cable_names not defined.\n");
+		return -EINVAL;
+	}
+
+	data->dev = &pdev->dev;
+	data->edev = devm_extcon_dev_allocate(&pdev->dev, pdata->cable_names);
+	if (IS_ERR(data->edev)) {
+		dev_err(&pdev->dev, "failed to allocate extcon device\n");
+		return -ENOMEM;
+	}
+
+	if (!pdata->adc_conditions) {
+		dev_err(&pdev->dev, "error: adc_conditions not defined.\n");
+		return -EINVAL;
+	}
+	data->adc_conditions = pdata->adc_conditions;
+
+	/* Check the length of array and set num_conditions */
+	for (i = 0; data->adc_conditions[i].id != EXTCON_NONE; i++);
+	data->num_conditions = i;
+
+	data->chan = devm_iio_channel_get(&pdev->dev, pdata->consumer_channel);
+	if (IS_ERR(data->chan))
+		return PTR_ERR(data->chan);
+
+	data->handling_delay = msecs_to_jiffies(pdata->handling_delay_ms);
+	data->wakeup_source = pdata->wakeup_source;
+
+	INIT_DEFERRABLE_WORK(&data->handler, adc_jack_handler);
+
+	platform_set_drvdata(pdev, data);
+
+	err = devm_extcon_dev_register(&pdev->dev, data->edev);
+	if (err)
+		return err;
+
+	data->irq = platform_get_irq(pdev, 0);
+	if (data->irq < 0)
+		return -ENODEV;
+
+	err = request_any_context_irq(data->irq, adc_jack_irq_thread,
+			pdata->irq_flags, pdata->name, data);
+
+	if (err < 0) {
+		dev_err(&pdev->dev, "error: irq %d\n", data->irq);
+		return err;
+	}
+
+	if (data->wakeup_source)
+		device_init_wakeup(&pdev->dev, 1);
+
+	adc_jack_handler(&data->handler.work);
+	return 0;
+}
+
+static void adc_jack_remove(struct platform_device *pdev)
+{
+	struct adc_jack_data *data = platform_get_drvdata(pdev);
+
+	if (data->wakeup_source)
+		device_init_wakeup(&pdev->dev, false);
+	free_irq(data->irq, data);
+	cancel_work_sync(&data->handler.work);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int adc_jack_suspend(struct device *dev)
+{
+	struct adc_jack_data *data = dev_get_drvdata(dev);
+
+	cancel_delayed_work_sync(&data->handler);
+	if (device_may_wakeup(data->dev))
+		enable_irq_wake(data->irq);
+
+	return 0;
+}
+
+static int adc_jack_resume(struct device *dev)
+{
+	struct adc_jack_data *data = dev_get_drvdata(dev);
+
+	if (device_may_wakeup(data->dev))
+		disable_irq_wake(data->irq);
+
+	return 0;
+}
+#endif /* CONFIG_PM_SLEEP */
+
+static SIMPLE_DEV_PM_OPS(adc_jack_pm_ops,
+		adc_jack_suspend, adc_jack_resume);
+
+static struct platform_driver adc_jack_driver = {
+	.probe          = adc_jack_probe,
+	.remove         = adc_jack_remove,
+	.driver         = {
+		.name   = "adc-jack",
+		.pm = &adc_jack_pm_ops,
+	},
+};
+
+module_platform_driver(adc_jack_driver);
+
+MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
+MODULE_DESCRIPTION("ADC Jack extcon driver");
+MODULE_LICENSE("GPL v2");
+MODULE_IMPORT_NS("IIO_CONSUMER");