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, 122 insertions, 0 deletions

diff --git a/drivers/mfd/rt5120.c b/drivers/mfd/rt5120.c
new file mode 100644
index 000000000..a229eb292
--- /dev/null
+++ b/drivers/mfd/rt5120.c
@@ -0,0 +1,122 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2022 Richtek Technology Corp.
+ * Author: ChiYuan Huang <cy_huang@richtek.com>
+ */
+
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/mfd/core.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+
+#define RT5120_REG_INTENABLE	0x1D
+#define RT5120_REG_INTSTAT	0x1E
+#define RT5120_REG_FZCMODE	0x44
+
+#define RT5120_INT_HOTDIE	0
+#define RT5120_INT_PWRKEY_REL	5
+#define RT5120_INT_PWRKEY_PRESS	6
+
+static const struct regmap_range rt5120_rd_yes_ranges[] = {
+	regmap_reg_range(0x03, 0x13),
+	regmap_reg_range(0x1c, 0x20),
+	regmap_reg_range(0x44, 0x44),
+};
+
+static const struct regmap_range rt5120_wr_yes_ranges[] = {
+	regmap_reg_range(0x06, 0x13),
+	regmap_reg_range(0x1c, 0x20),
+	regmap_reg_range(0x44, 0x44),
+};
+
+static const struct regmap_access_table rt5120_rd_table = {
+	.yes_ranges = rt5120_rd_yes_ranges,
+	.n_yes_ranges = ARRAY_SIZE(rt5120_rd_yes_ranges),
+};
+
+static const struct regmap_access_table rt5120_wr_table = {
+	.yes_ranges = rt5120_wr_yes_ranges,
+	.n_yes_ranges = ARRAY_SIZE(rt5120_wr_yes_ranges),
+};
+
+static const struct regmap_config rt5120_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = RT5120_REG_FZCMODE,
+
+	.wr_table = &rt5120_wr_table,
+	.rd_table = &rt5120_rd_table,
+};
+
+static const struct regmap_irq rt5120_irqs[] = {
+	REGMAP_IRQ_REG_LINE(RT5120_INT_HOTDIE, 8),
+	REGMAP_IRQ_REG_LINE(RT5120_INT_PWRKEY_REL, 8),
+	REGMAP_IRQ_REG_LINE(RT5120_INT_PWRKEY_PRESS, 8),
+};
+
+static const struct regmap_irq_chip rt5120_irq_chip = {
+	.name = "rt5120-pmic",
+	.status_base = RT5120_REG_INTSTAT,
+	.unmask_base = RT5120_REG_INTENABLE,
+	.ack_base = RT5120_REG_INTSTAT,
+	.use_ack = true,
+	.num_regs = 1,
+	.irqs = rt5120_irqs,
+	.num_irqs = ARRAY_SIZE(rt5120_irqs),
+};
+
+static const struct resource rt5120_regulator_resources[] = {
+	DEFINE_RES_IRQ(RT5120_INT_HOTDIE),
+};
+
+static const struct resource rt5120_pwrkey_resources[] = {
+	DEFINE_RES_IRQ_NAMED(RT5120_INT_PWRKEY_PRESS, "pwrkey-press"),
+	DEFINE_RES_IRQ_NAMED(RT5120_INT_PWRKEY_REL, "pwrkey-release"),
+};
+
+static const struct mfd_cell rt5120_devs[] = {
+	MFD_CELL_RES("rt5120-regulator", rt5120_regulator_resources),
+	MFD_CELL_OF("rt5120-pwrkey", rt5120_pwrkey_resources, NULL, 0, 0, "richtek,rt5120-pwrkey"),
+};
+
+static int rt5120_probe(struct i2c_client *i2c)
+{
+	struct device *dev = &i2c->dev;
+	struct regmap *regmap;
+	struct regmap_irq_chip_data *irq_data;
+	int ret;
+
+	regmap = devm_regmap_init_i2c(i2c, &rt5120_regmap_config);
+	if (IS_ERR(regmap))
+		return dev_err_probe(dev, PTR_ERR(regmap),
+				     "Failed to init regmap\n");
+
+	ret = devm_regmap_add_irq_chip(dev, regmap, i2c->irq, IRQF_ONESHOT, 0,
+				       &rt5120_irq_chip, &irq_data);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to add IRQ chip\n");
+
+	return devm_mfd_add_devices(dev, PLATFORM_DEVID_AUTO, rt5120_devs,
+				    ARRAY_SIZE(rt5120_devs), NULL, 0,
+				    regmap_irq_get_domain(irq_data));
+}
+
+static const struct of_device_id rt5120_device_match_table[] = {
+	{ .compatible = "richtek,rt5120" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, rt5120_device_match_table);
+
+static struct i2c_driver rt5120_driver = {
+	.driver = {
+		.name = "rt5120",
+		.of_match_table = rt5120_device_match_table,
+	},
+	.probe = rt5120_probe,
+};
+module_i2c_driver(rt5120_driver);
+
+MODULE_AUTHOR("ChiYuan Huang <cy_huang@richtek.com>");
+MODULE_DESCRIPTION("Richtek RT5120 I2C driver");
+MODULE_LICENSE("GPL v2");