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, 278 insertions, 0 deletions

diff --git a/drivers/mfd/max77686.c b/drivers/mfd/max77686.c
new file mode 100644
index 000000000..0118a444a
--- /dev/null
+++ b/drivers/mfd/max77686.c
@@ -0,0 +1,278 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// max77686.c - mfd core driver for the Maxim 77686/802
+//
+// Copyright (C) 2012 Samsung Electronics
+// Chiwoong Byun <woong.byun@samsung.com>
+// Jonghwa Lee <jonghwa3.lee@samsung.com>
+//
+//This driver is based on max8997.c
+
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+#include <linux/pm_runtime.h>
+#include <linux/module.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/max77686.h>
+#include <linux/mfd/max77686-private.h>
+#include <linux/err.h>
+#include <linux/of.h>
+
+static const struct mfd_cell max77686_devs[] = {
+	{ .name = "max77686-pmic", },
+	{ .name = "max77686-rtc", },
+	{ .name = "max77686-clk", },
+};
+
+static const struct mfd_cell max77802_devs[] = {
+	{ .name = "max77802-pmic", },
+	{ .name = "max77802-clk", },
+	{ .name = "max77802-rtc", },
+};
+
+static bool max77802_pmic_is_accessible_reg(struct device *dev,
+					    unsigned int reg)
+{
+	return reg < MAX77802_REG_PMIC_END;
+}
+
+static bool max77802_rtc_is_accessible_reg(struct device *dev,
+					   unsigned int reg)
+{
+	return (reg >= MAX77802_RTC_INT && reg < MAX77802_RTC_END);
+}
+
+static bool max77802_is_accessible_reg(struct device *dev, unsigned int reg)
+{
+	return (max77802_pmic_is_accessible_reg(dev, reg) ||
+		max77802_rtc_is_accessible_reg(dev, reg));
+}
+
+static bool max77802_pmic_is_precious_reg(struct device *dev, unsigned int reg)
+{
+	return (reg == MAX77802_REG_INTSRC || reg == MAX77802_REG_INT1 ||
+		reg == MAX77802_REG_INT2);
+}
+
+static bool max77802_rtc_is_precious_reg(struct device *dev, unsigned int reg)
+{
+	return (reg == MAX77802_RTC_INT ||
+		reg == MAX77802_RTC_UPDATE0 ||
+		reg == MAX77802_RTC_UPDATE1);
+}
+
+static bool max77802_is_precious_reg(struct device *dev, unsigned int reg)
+{
+	return (max77802_pmic_is_precious_reg(dev, reg) ||
+		max77802_rtc_is_precious_reg(dev, reg));
+}
+
+static bool max77802_pmic_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+	return (max77802_is_precious_reg(dev, reg) ||
+		reg == MAX77802_REG_STATUS1 || reg == MAX77802_REG_STATUS2 ||
+		reg == MAX77802_REG_PWRON);
+}
+
+static bool max77802_rtc_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+	return (max77802_rtc_is_precious_reg(dev, reg) ||
+		reg == MAX77802_RTC_SEC ||
+		reg == MAX77802_RTC_MIN ||
+		reg == MAX77802_RTC_HOUR ||
+		reg == MAX77802_RTC_WEEKDAY ||
+		reg == MAX77802_RTC_MONTH ||
+		reg == MAX77802_RTC_YEAR ||
+		reg == MAX77802_RTC_MONTHDAY);
+}
+
+static bool max77802_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+	return (max77802_pmic_is_volatile_reg(dev, reg) ||
+		max77802_rtc_is_volatile_reg(dev, reg));
+}
+
+static const struct regmap_config max77686_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+};
+
+static const struct regmap_config max77802_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.writeable_reg = max77802_is_accessible_reg,
+	.readable_reg = max77802_is_accessible_reg,
+	.precious_reg = max77802_is_precious_reg,
+	.volatile_reg = max77802_is_volatile_reg,
+	.name = "max77802-pmic",
+	.cache_type = REGCACHE_MAPLE,
+};
+
+static const struct regmap_irq max77686_irqs[] = {
+	/* INT1 interrupts */
+	{ .reg_offset = 0, .mask = MAX77686_INT1_PWRONF_MSK, },
+	{ .reg_offset = 0, .mask = MAX77686_INT1_PWRONR_MSK, },
+	{ .reg_offset = 0, .mask = MAX77686_INT1_JIGONBF_MSK, },
+	{ .reg_offset = 0, .mask = MAX77686_INT1_JIGONBR_MSK, },
+	{ .reg_offset = 0, .mask = MAX77686_INT1_ACOKBF_MSK, },
+	{ .reg_offset = 0, .mask = MAX77686_INT1_ACOKBR_MSK, },
+	{ .reg_offset = 0, .mask = MAX77686_INT1_ONKEY1S_MSK, },
+	{ .reg_offset = 0, .mask = MAX77686_INT1_MRSTB_MSK, },
+	/* INT2 interrupts */
+	{ .reg_offset = 1, .mask = MAX77686_INT2_140C_MSK, },
+	{ .reg_offset = 1, .mask = MAX77686_INT2_120C_MSK, },
+};
+
+static const struct regmap_irq_chip max77686_irq_chip = {
+	.name			= "max77686-pmic",
+	.status_base		= MAX77686_REG_INT1,
+	.mask_base		= MAX77686_REG_INT1MSK,
+	.num_regs		= 2,
+	.irqs			= max77686_irqs,
+	.num_irqs		= ARRAY_SIZE(max77686_irqs),
+};
+
+static const struct regmap_irq_chip max77802_irq_chip = {
+	.name			= "max77802-pmic",
+	.status_base		= MAX77802_REG_INT1,
+	.mask_base		= MAX77802_REG_INT1MSK,
+	.num_regs		= 2,
+	.irqs			= max77686_irqs, /* same masks as 77686 */
+	.num_irqs		= ARRAY_SIZE(max77686_irqs),
+};
+
+static const struct of_device_id max77686_pmic_dt_match[] = {
+	{
+		.compatible = "maxim,max77686",
+		.data = (void *)TYPE_MAX77686,
+	},
+	{
+		.compatible = "maxim,max77802",
+		.data = (void *)TYPE_MAX77802,
+	},
+	{ },
+};
+MODULE_DEVICE_TABLE(of, max77686_pmic_dt_match);
+
+static int max77686_i2c_probe(struct i2c_client *i2c)
+{
+	struct max77686_dev *max77686 = NULL;
+	unsigned int data;
+	int ret = 0;
+	const struct regmap_config *config;
+	const struct regmap_irq_chip *irq_chip;
+	const struct mfd_cell *cells;
+	int n_devs;
+
+	max77686 = devm_kzalloc(&i2c->dev,
+				sizeof(struct max77686_dev), GFP_KERNEL);
+	if (!max77686)
+		return -ENOMEM;
+
+	i2c_set_clientdata(i2c, max77686);
+	max77686->type = (unsigned long)of_device_get_match_data(&i2c->dev);
+	max77686->dev = &i2c->dev;
+	max77686->i2c = i2c;
+
+	max77686->irq = i2c->irq;
+
+	if (max77686->type == TYPE_MAX77686) {
+		config = &max77686_regmap_config;
+		irq_chip = &max77686_irq_chip;
+		cells =  max77686_devs;
+		n_devs = ARRAY_SIZE(max77686_devs);
+	} else {
+		config = &max77802_regmap_config;
+		irq_chip = &max77802_irq_chip;
+		cells =  max77802_devs;
+		n_devs = ARRAY_SIZE(max77802_devs);
+	}
+
+	max77686->regmap = devm_regmap_init_i2c(i2c, config);
+	if (IS_ERR(max77686->regmap)) {
+		ret = PTR_ERR(max77686->regmap);
+		dev_err(max77686->dev, "Failed to allocate register map: %d\n",
+				ret);
+		return ret;
+	}
+
+	ret = regmap_read(max77686->regmap, MAX77686_REG_DEVICE_ID, &data);
+	if (ret < 0) {
+		dev_err(max77686->dev,
+			"device not found on this channel (this is not an error)\n");
+		return -ENODEV;
+	}
+
+	ret = devm_regmap_add_irq_chip(&i2c->dev, max77686->regmap,
+				       max77686->irq,
+				       IRQF_ONESHOT | IRQF_SHARED, 0, irq_chip,
+				       &max77686->irq_data);
+	if (ret < 0) {
+		dev_err(&i2c->dev, "failed to add PMIC irq chip: %d\n", ret);
+		return ret;
+	}
+
+	ret = devm_mfd_add_devices(max77686->dev, -1, cells, n_devs, NULL,
+				   0, NULL);
+	if (ret < 0) {
+		dev_err(&i2c->dev, "failed to add MFD devices: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int max77686_suspend(struct device *dev)
+{
+	struct i2c_client *i2c = to_i2c_client(dev);
+	struct max77686_dev *max77686 = i2c_get_clientdata(i2c);
+
+	if (device_may_wakeup(dev))
+		enable_irq_wake(max77686->irq);
+
+	/*
+	 * IRQ must be disabled during suspend because if it happens
+	 * while suspended it will be handled before resuming I2C.
+	 *
+	 * When device is woken up from suspend (e.g. by RTC wake alarm),
+	 * an interrupt occurs before resuming I2C bus controller.
+	 * Interrupt handler tries to read registers but this read
+	 * will fail because I2C is still suspended.
+	 */
+	disable_irq(max77686->irq);
+
+	return 0;
+}
+
+static int max77686_resume(struct device *dev)
+{
+	struct i2c_client *i2c = to_i2c_client(dev);
+	struct max77686_dev *max77686 = i2c_get_clientdata(i2c);
+
+	if (device_may_wakeup(dev))
+		disable_irq_wake(max77686->irq);
+
+	enable_irq(max77686->irq);
+
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(max77686_pm, max77686_suspend, max77686_resume);
+
+static struct i2c_driver max77686_i2c_driver = {
+	.driver = {
+		   .name = "max77686",
+		   .pm = pm_sleep_ptr(&max77686_pm),
+		   .of_match_table = max77686_pmic_dt_match,
+	},
+	.probe = max77686_i2c_probe,
+};
+
+module_i2c_driver(max77686_i2c_driver);
+
+MODULE_DESCRIPTION("MAXIM 77686/802 multi-function core driver");
+MODULE_AUTHOR("Chiwoong Byun <woong.byun@samsung.com>");
+MODULE_LICENSE("GPL");