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/mfd/max77843.c b/drivers/mfd/max77843.c
new file mode 100644
index 000000000..2a48577b1
--- /dev/null
+++ b/drivers/mfd/max77843.c
@@ -0,0 +1,217 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// MFD core driver for the Maxim MAX77843
+//
+// Copyright (C) 2015 Samsung Electronics
+// Author: Jaewon Kim <jaewon02.kim@samsung.com>
+// Author: Beomho Seo <beomho.seo@samsung.com>
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/max77693-common.h>
+#include <linux/mfd/max77843-private.h>
+#include <linux/platform_device.h>
+
+static const struct mfd_cell max77843_devs[] = {
+	{
+		.name = "max77843-muic",
+		.of_compatible = "maxim,max77843-muic",
+	}, {
+		.name = "max77843-regulator",
+		.of_compatible = "maxim,max77843-regulator",
+	}, {
+		.name = "max77843-charger",
+		.of_compatible = "maxim,max77843-charger"
+	}, {
+		.name = "max77843-fuelgauge",
+		.of_compatible = "maxim,max77843-fuelgauge",
+	}, {
+		.name = "max77843-haptic",
+		.of_compatible = "maxim,max77843-haptic",
+	},
+};
+
+static const struct regmap_config max77843_charger_regmap_config = {
+	.reg_bits	= 8,
+	.val_bits	= 8,
+	.max_register	= MAX77843_CHG_REG_END,
+};
+
+static const struct regmap_config max77843_regmap_config = {
+	.reg_bits	= 8,
+	.val_bits	= 8,
+	.max_register	= MAX77843_SYS_REG_END,
+};
+
+static const struct regmap_irq max77843_irqs[] = {
+	/* TOPSYS interrupts */
+	{ .reg_offset = 0, .mask = MAX77843_SYS_IRQ_SYSUVLO_INT, },
+	{ .reg_offset = 0, .mask = MAX77843_SYS_IRQ_SYSOVLO_INT, },
+	{ .reg_offset = 0, .mask = MAX77843_SYS_IRQ_TSHDN_INT, },
+	{ .reg_offset = 0, .mask = MAX77843_SYS_IRQ_TM_INT, },
+};
+
+static const struct regmap_irq_chip max77843_irq_chip = {
+	.name		= "max77843",
+	.status_base	= MAX77843_SYS_REG_SYSINTSRC,
+	.mask_base	= MAX77843_SYS_REG_SYSINTMASK,
+	.num_regs	= 1,
+	.irqs		= max77843_irqs,
+	.num_irqs	= ARRAY_SIZE(max77843_irqs),
+};
+
+/* Charger and Charger regulator use same regmap. */
+static int max77843_chg_init(struct max77693_dev *max77843)
+{
+	int ret;
+
+	max77843->i2c_chg = i2c_new_dummy_device(max77843->i2c->adapter, I2C_ADDR_CHG);
+	if (IS_ERR(max77843->i2c_chg)) {
+		dev_err(&max77843->i2c->dev,
+				"Cannot allocate I2C device for Charger\n");
+		return PTR_ERR(max77843->i2c_chg);
+	}
+	i2c_set_clientdata(max77843->i2c_chg, max77843);
+
+	max77843->regmap_chg = devm_regmap_init_i2c(max77843->i2c_chg,
+			&max77843_charger_regmap_config);
+	if (IS_ERR(max77843->regmap_chg)) {
+		ret = PTR_ERR(max77843->regmap_chg);
+		goto err_chg_i2c;
+	}
+
+	return 0;
+
+err_chg_i2c:
+	i2c_unregister_device(max77843->i2c_chg);
+
+	return ret;
+}
+
+static int max77843_probe(struct i2c_client *i2c)
+{
+	const struct i2c_device_id *id = i2c_client_get_device_id(i2c);
+	struct max77693_dev *max77843;
+	unsigned int reg_data;
+	int ret;
+
+	max77843 = devm_kzalloc(&i2c->dev, sizeof(*max77843), GFP_KERNEL);
+	if (!max77843)
+		return -ENOMEM;
+
+	i2c_set_clientdata(i2c, max77843);
+	max77843->dev = &i2c->dev;
+	max77843->i2c = i2c;
+	max77843->irq = i2c->irq;
+	max77843->type = id->driver_data;
+
+	max77843->regmap = devm_regmap_init_i2c(i2c,
+			&max77843_regmap_config);
+	if (IS_ERR(max77843->regmap)) {
+		dev_err(&i2c->dev, "Failed to allocate topsys register map\n");
+		return PTR_ERR(max77843->regmap);
+	}
+
+	ret = regmap_add_irq_chip(max77843->regmap, max77843->irq,
+			IRQF_TRIGGER_LOW | IRQF_ONESHOT | IRQF_SHARED,
+			0, &max77843_irq_chip, &max77843->irq_data_topsys);
+	if (ret) {
+		dev_err(&i2c->dev, "Failed to add TOPSYS IRQ chip\n");
+		return ret;
+	}
+
+	ret = regmap_read(max77843->regmap,
+			MAX77843_SYS_REG_PMICID, &reg_data);
+	if (ret < 0) {
+		dev_err(&i2c->dev, "Failed to read PMIC ID\n");
+		goto err_pmic_id;
+	}
+	dev_info(&i2c->dev, "device ID: 0x%x\n", reg_data);
+
+	ret = max77843_chg_init(max77843);
+	if (ret) {
+		dev_err(&i2c->dev, "Failed to init Charger\n");
+		goto err_pmic_id;
+	}
+
+	ret = regmap_update_bits(max77843->regmap,
+				 MAX77843_SYS_REG_INTSRCMASK,
+				 MAX77843_INTSRC_MASK_MASK,
+				 (unsigned int)~MAX77843_INTSRC_MASK_MASK);
+	if (ret < 0) {
+		dev_err(&i2c->dev, "Failed to unmask interrupt source\n");
+		goto err_pmic_id;
+	}
+
+	ret = mfd_add_devices(max77843->dev, -1, max77843_devs,
+			      ARRAY_SIZE(max77843_devs), NULL, 0, NULL);
+	if (ret < 0) {
+		dev_err(&i2c->dev, "Failed to add mfd device\n");
+		goto err_pmic_id;
+	}
+
+	device_init_wakeup(max77843->dev, true);
+
+	return 0;
+
+err_pmic_id:
+	regmap_del_irq_chip(max77843->irq, max77843->irq_data_topsys);
+
+	return ret;
+}
+
+static const struct of_device_id max77843_dt_match[] = {
+	{ .compatible = "maxim,max77843", },
+	{ },
+};
+
+static const struct i2c_device_id max77843_id[] = {
+	{ "max77843", TYPE_MAX77843, },
+	{ },
+};
+
+static int __maybe_unused max77843_suspend(struct device *dev)
+{
+	struct i2c_client *i2c = to_i2c_client(dev);
+	struct max77693_dev *max77843 = i2c_get_clientdata(i2c);
+
+	disable_irq(max77843->irq);
+	if (device_may_wakeup(dev))
+		enable_irq_wake(max77843->irq);
+
+	return 0;
+}
+
+static int __maybe_unused max77843_resume(struct device *dev)
+{
+	struct i2c_client *i2c = to_i2c_client(dev);
+	struct max77693_dev *max77843 = i2c_get_clientdata(i2c);
+
+	if (device_may_wakeup(dev))
+		disable_irq_wake(max77843->irq);
+	enable_irq(max77843->irq);
+
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(max77843_pm, max77843_suspend, max77843_resume);
+
+static struct i2c_driver max77843_i2c_driver = {
+	.driver	= {
+		.name = "max77843",
+		.pm = &max77843_pm,
+		.of_match_table = max77843_dt_match,
+		.suppress_bind_attrs = true,
+	},
+	.probe = max77843_probe,
+	.id_table = max77843_id,
+};
+
+static int __init max77843_i2c_init(void)
+{
+	return i2c_add_driver(&max77843_i2c_driver);
+}
+subsys_initcall(max77843_i2c_init);