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, 413 insertions, 0 deletions

diff --git a/drivers/input/misc/axp20x-pek.c b/drivers/input/misc/axp20x-pek.c
new file mode 100644
index 000000000..24f9e9d89
--- /dev/null
+++ b/drivers/input/misc/axp20x-pek.c
@@ -0,0 +1,413 @@
+/*
+ * axp20x power button driver.
+ *
+ * Copyright (C) 2013 Carlo Caione <carlo@caione.org>
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License. See the file "COPYING" in the main directory of this
+ * archive for more details.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/acpi.h>
+#include <linux/errno.h>
+#include <linux/irq.h>
+#include <linux/init.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/mfd/axp20x.h>
+#include <linux/module.h>
+#include <linux/platform_data/x86/soc.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+#define AXP20X_PEK_STARTUP_MASK		(0xc0)
+#define AXP20X_PEK_SHUTDOWN_MASK	(0x03)
+
+struct axp20x_info {
+	const struct axp20x_time *startup_time;
+	unsigned int startup_mask;
+	const struct axp20x_time *shutdown_time;
+	unsigned int shutdown_mask;
+};
+
+struct axp20x_pek {
+	struct axp20x_dev *axp20x;
+	struct input_dev *input;
+	struct axp20x_info *info;
+	int irq_dbr;
+	int irq_dbf;
+};
+
+struct axp20x_time {
+	unsigned int time;
+	unsigned int idx;
+};
+
+static const struct axp20x_time startup_time[] = {
+	{ .time = 128,  .idx = 0 },
+	{ .time = 1000, .idx = 2 },
+	{ .time = 3000, .idx = 1 },
+	{ .time = 2000, .idx = 3 },
+};
+
+static const struct axp20x_time axp221_startup_time[] = {
+	{ .time = 128,  .idx = 0 },
+	{ .time = 1000, .idx = 1 },
+	{ .time = 2000, .idx = 2 },
+	{ .time = 3000, .idx = 3 },
+};
+
+static const struct axp20x_time shutdown_time[] = {
+	{ .time = 4000,  .idx = 0 },
+	{ .time = 6000,  .idx = 1 },
+	{ .time = 8000,  .idx = 2 },
+	{ .time = 10000, .idx = 3 },
+};
+
+static const struct axp20x_info axp20x_info = {
+	.startup_time = startup_time,
+	.startup_mask = AXP20X_PEK_STARTUP_MASK,
+	.shutdown_time = shutdown_time,
+	.shutdown_mask = AXP20X_PEK_SHUTDOWN_MASK,
+};
+
+static const struct axp20x_info axp221_info = {
+	.startup_time = axp221_startup_time,
+	.startup_mask = AXP20X_PEK_STARTUP_MASK,
+	.shutdown_time = shutdown_time,
+	.shutdown_mask = AXP20X_PEK_SHUTDOWN_MASK,
+};
+
+static ssize_t axp20x_show_attr(struct device *dev,
+				const struct axp20x_time *time,
+				unsigned int mask, char *buf)
+{
+	struct axp20x_pek *axp20x_pek = dev_get_drvdata(dev);
+	unsigned int val;
+	int ret, i;
+
+	ret = regmap_read(axp20x_pek->axp20x->regmap, AXP20X_PEK_KEY, &val);
+	if (ret != 0)
+		return ret;
+
+	val &= mask;
+	val >>= ffs(mask) - 1;
+
+	for (i = 0; i < 4; i++)
+		if (val == time[i].idx)
+			val = time[i].time;
+
+	return sprintf(buf, "%u\n", val);
+}
+
+static ssize_t axp20x_show_attr_startup(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct axp20x_pek *axp20x_pek = dev_get_drvdata(dev);
+
+	return axp20x_show_attr(dev, axp20x_pek->info->startup_time,
+				axp20x_pek->info->startup_mask, buf);
+}
+
+static ssize_t axp20x_show_attr_shutdown(struct device *dev,
+					 struct device_attribute *attr,
+					 char *buf)
+{
+	struct axp20x_pek *axp20x_pek = dev_get_drvdata(dev);
+
+	return axp20x_show_attr(dev, axp20x_pek->info->shutdown_time,
+				axp20x_pek->info->shutdown_mask, buf);
+}
+
+static ssize_t axp20x_store_attr(struct device *dev,
+				 const struct axp20x_time *time,
+				 unsigned int mask, const char *buf,
+				 size_t count)
+{
+	struct axp20x_pek *axp20x_pek = dev_get_drvdata(dev);
+	int ret, i;
+	unsigned int val, idx = 0;
+	unsigned int best_err = UINT_MAX;
+
+	ret = kstrtouint(buf, 10, &val);
+	if (ret)
+		return ret;
+
+	for (i = 3; i >= 0; i--) {
+		unsigned int err;
+
+		err = abs(time[i].time - val);
+		if (err < best_err) {
+			best_err = err;
+			idx = time[i].idx;
+		}
+
+		if (!err)
+			break;
+	}
+
+	idx <<= ffs(mask) - 1;
+	ret = regmap_update_bits(axp20x_pek->axp20x->regmap, AXP20X_PEK_KEY,
+				 mask, idx);
+	if (ret != 0)
+		return -EINVAL;
+
+	return count;
+}
+
+static ssize_t axp20x_store_attr_startup(struct device *dev,
+					 struct device_attribute *attr,
+					 const char *buf, size_t count)
+{
+	struct axp20x_pek *axp20x_pek = dev_get_drvdata(dev);
+
+	return axp20x_store_attr(dev, axp20x_pek->info->startup_time,
+				 axp20x_pek->info->startup_mask, buf, count);
+}
+
+static ssize_t axp20x_store_attr_shutdown(struct device *dev,
+					  struct device_attribute *attr,
+					  const char *buf, size_t count)
+{
+	struct axp20x_pek *axp20x_pek = dev_get_drvdata(dev);
+
+	return axp20x_store_attr(dev, axp20x_pek->info->shutdown_time,
+				 axp20x_pek->info->shutdown_mask, buf, count);
+}
+
+static DEVICE_ATTR(startup, 0644, axp20x_show_attr_startup,
+		   axp20x_store_attr_startup);
+static DEVICE_ATTR(shutdown, 0644, axp20x_show_attr_shutdown,
+		   axp20x_store_attr_shutdown);
+
+static struct attribute *axp20x_attrs[] = {
+	&dev_attr_startup.attr,
+	&dev_attr_shutdown.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(axp20x);
+
+static irqreturn_t axp20x_pek_irq(int irq, void *pwr)
+{
+	struct input_dev *idev = pwr;
+	struct axp20x_pek *axp20x_pek = input_get_drvdata(idev);
+
+	/*
+	 * The power-button is connected to ground so a falling edge (dbf)
+	 * means it is pressed.
+	 */
+	if (irq == axp20x_pek->irq_dbf)
+		input_report_key(idev, KEY_POWER, true);
+	else if (irq == axp20x_pek->irq_dbr)
+		input_report_key(idev, KEY_POWER, false);
+
+	input_sync(idev);
+
+	return IRQ_HANDLED;
+}
+
+static int axp20x_pek_probe_input_device(struct axp20x_pek *axp20x_pek,
+					 struct platform_device *pdev)
+{
+	struct axp20x_dev *axp20x = axp20x_pek->axp20x;
+	struct input_dev *idev;
+	int error;
+
+	axp20x_pek->irq_dbr = platform_get_irq_byname(pdev, "PEK_DBR");
+	if (axp20x_pek->irq_dbr < 0)
+		return axp20x_pek->irq_dbr;
+	axp20x_pek->irq_dbr = regmap_irq_get_virq(axp20x->regmap_irqc,
+						  axp20x_pek->irq_dbr);
+
+	axp20x_pek->irq_dbf = platform_get_irq_byname(pdev, "PEK_DBF");
+	if (axp20x_pek->irq_dbf < 0)
+		return axp20x_pek->irq_dbf;
+	axp20x_pek->irq_dbf = regmap_irq_get_virq(axp20x->regmap_irqc,
+						  axp20x_pek->irq_dbf);
+
+	axp20x_pek->input = devm_input_allocate_device(&pdev->dev);
+	if (!axp20x_pek->input)
+		return -ENOMEM;
+
+	idev = axp20x_pek->input;
+
+	idev->name = "axp20x-pek";
+	idev->phys = "m1kbd/input2";
+	idev->dev.parent = &pdev->dev;
+
+	input_set_capability(idev, EV_KEY, KEY_POWER);
+
+	input_set_drvdata(idev, axp20x_pek);
+
+	error = devm_request_any_context_irq(&pdev->dev, axp20x_pek->irq_dbr,
+					     axp20x_pek_irq, 0,
+					     "axp20x-pek-dbr", idev);
+	if (error < 0) {
+		dev_err(&pdev->dev, "Failed to request dbr IRQ#%d: %d\n",
+			axp20x_pek->irq_dbr, error);
+		return error;
+	}
+
+	error = devm_request_any_context_irq(&pdev->dev, axp20x_pek->irq_dbf,
+					  axp20x_pek_irq, 0,
+					  "axp20x-pek-dbf", idev);
+	if (error < 0) {
+		dev_err(&pdev->dev, "Failed to request dbf IRQ#%d: %d\n",
+			axp20x_pek->irq_dbf, error);
+		return error;
+	}
+
+	error = input_register_device(idev);
+	if (error) {
+		dev_err(&pdev->dev, "Can't register input device: %d\n",
+			error);
+		return error;
+	}
+
+	device_init_wakeup(&pdev->dev, true);
+
+	return 0;
+}
+
+static bool axp20x_pek_should_register_input(struct axp20x_pek *axp20x_pek)
+{
+	if (IS_ENABLED(CONFIG_INPUT_SOC_BUTTON_ARRAY) &&
+	    axp20x_pek->axp20x->variant == AXP288_ID) {
+		/*
+		 * On Cherry Trail platforms (hrv == 3), do not register the
+		 * input device if there is an "INTCFD9" or "ACPI0011" gpio
+		 * button ACPI device, as that handles the power button too,
+		 * and otherwise we end up reporting all presses twice.
+		 */
+		if (soc_intel_is_cht() &&
+				(acpi_dev_present("INTCFD9", NULL, -1) ||
+				 acpi_dev_present("ACPI0011", NULL, -1)))
+			return false;
+	}
+
+	return true;
+}
+
+static int axp20x_pek_probe(struct platform_device *pdev)
+{
+	struct axp20x_pek *axp20x_pek;
+	const struct platform_device_id *match = platform_get_device_id(pdev);
+	int error;
+
+	if (!match) {
+		dev_err(&pdev->dev, "Failed to get platform_device_id\n");
+		return -EINVAL;
+	}
+
+	axp20x_pek = devm_kzalloc(&pdev->dev, sizeof(struct axp20x_pek),
+				  GFP_KERNEL);
+	if (!axp20x_pek)
+		return -ENOMEM;
+
+	axp20x_pek->axp20x = dev_get_drvdata(pdev->dev.parent);
+
+	if (axp20x_pek_should_register_input(axp20x_pek)) {
+		error = axp20x_pek_probe_input_device(axp20x_pek, pdev);
+		if (error)
+			return error;
+	}
+
+	axp20x_pek->info = (struct axp20x_info *)match->driver_data;
+
+	platform_set_drvdata(pdev, axp20x_pek);
+
+	return 0;
+}
+
+static int axp20x_pek_suspend(struct device *dev)
+{
+	struct axp20x_pek *axp20x_pek = dev_get_drvdata(dev);
+
+	/*
+	 * As nested threaded IRQs are not automatically disabled during
+	 * suspend, we must explicitly disable non-wakeup IRQs.
+	 */
+	if (device_may_wakeup(dev)) {
+		enable_irq_wake(axp20x_pek->irq_dbf);
+		enable_irq_wake(axp20x_pek->irq_dbr);
+	} else {
+		disable_irq(axp20x_pek->irq_dbf);
+		disable_irq(axp20x_pek->irq_dbr);
+	}
+
+	return 0;
+}
+
+static int axp20x_pek_resume(struct device *dev)
+{
+	struct axp20x_pek *axp20x_pek = dev_get_drvdata(dev);
+
+	if (device_may_wakeup(dev)) {
+		disable_irq_wake(axp20x_pek->irq_dbf);
+		disable_irq_wake(axp20x_pek->irq_dbr);
+	} else {
+		enable_irq(axp20x_pek->irq_dbf);
+		enable_irq(axp20x_pek->irq_dbr);
+	}
+
+	return 0;
+}
+
+static int __maybe_unused axp20x_pek_resume_noirq(struct device *dev)
+{
+	struct axp20x_pek *axp20x_pek = dev_get_drvdata(dev);
+
+	if (axp20x_pek->axp20x->variant != AXP288_ID)
+		return 0;
+
+	/*
+	 * Clear interrupts from button presses during suspend, to avoid
+	 * a wakeup power-button press getting reported to userspace.
+	 */
+	regmap_write(axp20x_pek->axp20x->regmap,
+		     AXP20X_IRQ1_STATE + AXP288_IRQ_POKN / 8,
+		     BIT(AXP288_IRQ_POKN % 8));
+
+	return 0;
+}
+
+static const struct dev_pm_ops axp20x_pek_pm_ops = {
+	SYSTEM_SLEEP_PM_OPS(axp20x_pek_suspend, axp20x_pek_resume)
+	.resume_noirq = pm_sleep_ptr(axp20x_pek_resume_noirq),
+};
+
+static const struct platform_device_id axp_pek_id_match[] = {
+	{
+		.name = "axp20x-pek",
+		.driver_data = (kernel_ulong_t)&axp20x_info,
+	},
+	{
+		.name = "axp221-pek",
+		.driver_data = (kernel_ulong_t)&axp221_info,
+	},
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(platform, axp_pek_id_match);
+
+static struct platform_driver axp20x_pek_driver = {
+	.probe		= axp20x_pek_probe,
+	.id_table	= axp_pek_id_match,
+	.driver		= {
+		.name		= "axp20x-pek",
+		.pm		= pm_sleep_ptr(&axp20x_pek_pm_ops),
+		.dev_groups	= axp20x_groups,
+	},
+};
+module_platform_driver(axp20x_pek_driver);
+
+MODULE_DESCRIPTION("axp20x Power Button");
+MODULE_AUTHOR("Carlo Caione <carlo@caione.org>");
+MODULE_LICENSE("GPL");