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, 160 insertions, 0 deletions

diff --git a/drivers/input/misc/tps65218-pwrbutton.c b/drivers/input/misc/tps65218-pwrbutton.c
new file mode 100644
index 000000000..fc450fce0
--- /dev/null
+++ b/drivers/input/misc/tps65218-pwrbutton.c
@@ -0,0 +1,160 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Texas Instruments' TPS65217 and TPS65218 Power Button Input Driver
+ *
+ * Copyright (C) 2014 Texas Instruments Incorporated - http://www.ti.com/
+ * Author: Felipe Balbi <balbi@ti.com>
+ * Author: Marcin Niestroj <m.niestroj@grinn-global.com>
+ */
+
+#include <linux/init.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/mfd/tps65217.h>
+#include <linux/mfd/tps65218.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+struct tps6521x_data {
+	unsigned int reg_status;
+	unsigned int pb_mask;
+	const char *name;
+};
+
+static const struct tps6521x_data tps65217_data = {
+	.reg_status = TPS65217_REG_STATUS,
+	.pb_mask = TPS65217_STATUS_PB,
+	.name = "tps65217_pwrbutton",
+};
+
+static const struct tps6521x_data tps65218_data = {
+	.reg_status = TPS65218_REG_STATUS,
+	.pb_mask = TPS65218_STATUS_PB_STATE,
+	.name = "tps65218_pwrbutton",
+};
+
+struct tps6521x_pwrbutton {
+	struct device *dev;
+	struct regmap *regmap;
+	struct input_dev *idev;
+	const struct tps6521x_data *data;
+	char phys[32];
+};
+
+static const struct of_device_id of_tps6521x_pb_match[] = {
+	{ .compatible = "ti,tps65217-pwrbutton", .data = &tps65217_data },
+	{ .compatible = "ti,tps65218-pwrbutton", .data = &tps65218_data },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, of_tps6521x_pb_match);
+
+static irqreturn_t tps6521x_pb_irq(int irq, void *_pwr)
+{
+	struct tps6521x_pwrbutton *pwr = _pwr;
+	const struct tps6521x_data *tps_data = pwr->data;
+	unsigned int reg;
+	int error;
+
+	error = regmap_read(pwr->regmap, tps_data->reg_status, &reg);
+	if (error) {
+		dev_err(pwr->dev, "can't read register: %d\n", error);
+		goto out;
+	}
+
+	if (reg & tps_data->pb_mask) {
+		input_report_key(pwr->idev, KEY_POWER, 1);
+		pm_wakeup_event(pwr->dev, 0);
+	} else {
+		input_report_key(pwr->idev, KEY_POWER, 0);
+	}
+
+	input_sync(pwr->idev);
+
+out:
+	return IRQ_HANDLED;
+}
+
+static int tps6521x_pb_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct tps6521x_pwrbutton *pwr;
+	struct input_dev *idev;
+	const struct of_device_id *match;
+	int error;
+	int irq;
+
+	match = of_match_node(of_tps6521x_pb_match, dev->of_node);
+	if (!match)
+		return -ENXIO;
+
+	pwr = devm_kzalloc(dev, sizeof(*pwr), GFP_KERNEL);
+	if (!pwr)
+		return -ENOMEM;
+
+	pwr->data = match->data;
+
+	idev = devm_input_allocate_device(dev);
+	if (!idev)
+		return -ENOMEM;
+
+	idev->name = pwr->data->name;
+	snprintf(pwr->phys, sizeof(pwr->phys), "%s/input0",
+		pwr->data->name);
+	idev->phys = pwr->phys;
+	idev->dev.parent = dev;
+	idev->id.bustype = BUS_I2C;
+
+	input_set_capability(idev, EV_KEY, KEY_POWER);
+
+	pwr->regmap = dev_get_regmap(dev->parent, NULL);
+	pwr->dev = dev;
+	pwr->idev = idev;
+	device_init_wakeup(dev, true);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return -EINVAL;
+
+	error = devm_request_threaded_irq(dev, irq, NULL, tps6521x_pb_irq,
+					  IRQF_TRIGGER_RISING |
+						IRQF_TRIGGER_FALLING |
+						IRQF_ONESHOT,
+					  pwr->data->name, pwr);
+	if (error) {
+		dev_err(dev, "failed to request IRQ #%d: %d\n", irq, error);
+		return error;
+	}
+
+	error= input_register_device(idev);
+	if (error) {
+		dev_err(dev, "Can't register power button: %d\n", error);
+		return error;
+	}
+
+	return 0;
+}
+
+static const struct platform_device_id tps6521x_pwrbtn_id_table[] = {
+	{ "tps65218-pwrbutton", },
+	{ "tps65217-pwrbutton", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(platform, tps6521x_pwrbtn_id_table);
+
+static struct platform_driver tps6521x_pb_driver = {
+	.probe	= tps6521x_pb_probe,
+	.driver	= {
+		.name	= "tps6521x_pwrbutton",
+		.of_match_table = of_tps6521x_pb_match,
+	},
+	.id_table = tps6521x_pwrbtn_id_table,
+};
+module_platform_driver(tps6521x_pb_driver);
+
+MODULE_DESCRIPTION("TPS6521X Power Button");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Felipe Balbi <balbi@ti.com>");