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, 143 insertions, 0 deletions

diff --git a/drivers/mfd/madera-i2c.c b/drivers/mfd/madera-i2c.c
new file mode 100644
index 000000000..0986e4a99
--- /dev/null
+++ b/drivers/mfd/madera-i2c.c
@@ -0,0 +1,143 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * I2C bus interface to Cirrus Logic Madera codecs
+ *
+ * Copyright (C) 2015-2018 Cirrus Logic
+ */
+
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+
+#include <linux/mfd/madera/core.h>
+
+#include "madera.h"
+
+static int madera_i2c_probe(struct i2c_client *i2c)
+{
+	struct madera *madera;
+	const struct regmap_config *regmap_16bit_config = NULL;
+	const struct regmap_config *regmap_32bit_config = NULL;
+	unsigned long type;
+	const char *name;
+	int ret;
+
+	type = (uintptr_t)i2c_get_match_data(i2c);
+	switch (type) {
+	case CS47L15:
+		if (IS_ENABLED(CONFIG_MFD_CS47L15)) {
+			regmap_16bit_config = &cs47l15_16bit_i2c_regmap;
+			regmap_32bit_config = &cs47l15_32bit_i2c_regmap;
+		}
+		break;
+	case CS47L35:
+		if (IS_ENABLED(CONFIG_MFD_CS47L35)) {
+			regmap_16bit_config = &cs47l35_16bit_i2c_regmap;
+			regmap_32bit_config = &cs47l35_32bit_i2c_regmap;
+		}
+		break;
+	case CS47L85:
+	case WM1840:
+		if (IS_ENABLED(CONFIG_MFD_CS47L85)) {
+			regmap_16bit_config = &cs47l85_16bit_i2c_regmap;
+			regmap_32bit_config = &cs47l85_32bit_i2c_regmap;
+		}
+		break;
+	case CS47L90:
+	case CS47L91:
+		if (IS_ENABLED(CONFIG_MFD_CS47L90)) {
+			regmap_16bit_config = &cs47l90_16bit_i2c_regmap;
+			regmap_32bit_config = &cs47l90_32bit_i2c_regmap;
+		}
+		break;
+	case CS42L92:
+	case CS47L92:
+	case CS47L93:
+		if (IS_ENABLED(CONFIG_MFD_CS47L92)) {
+			regmap_16bit_config = &cs47l92_16bit_i2c_regmap;
+			regmap_32bit_config = &cs47l92_32bit_i2c_regmap;
+		}
+		break;
+	default:
+		dev_err(&i2c->dev,
+			"Unknown Madera I2C device type %ld\n", type);
+		return -EINVAL;
+	}
+
+	name = madera_name_from_type(type);
+
+	if (!regmap_16bit_config) {
+		/* it's polite to say which codec isn't built into the kernel */
+		dev_err(&i2c->dev,
+			"Kernel does not include support for %s\n", name);
+		return -EINVAL;
+	}
+
+	madera = devm_kzalloc(&i2c->dev, sizeof(*madera), GFP_KERNEL);
+	if (!madera)
+		return -ENOMEM;
+
+	madera->regmap = devm_regmap_init_i2c(i2c, regmap_16bit_config);
+	if (IS_ERR(madera->regmap)) {
+		ret = PTR_ERR(madera->regmap);
+		dev_err(&i2c->dev,
+			"Failed to allocate 16-bit register map: %d\n",	ret);
+		return ret;
+	}
+
+	madera->regmap_32bit = devm_regmap_init_i2c(i2c, regmap_32bit_config);
+	if (IS_ERR(madera->regmap_32bit)) {
+		ret = PTR_ERR(madera->regmap_32bit);
+		dev_err(&i2c->dev,
+			"Failed to allocate 32-bit register map: %d\n", ret);
+		return ret;
+	}
+
+	madera->type = type;
+	madera->type_name = name;
+	madera->dev = &i2c->dev;
+	madera->irq = i2c->irq;
+
+	return madera_dev_init(madera);
+}
+
+static void madera_i2c_remove(struct i2c_client *i2c)
+{
+	struct madera *madera = dev_get_drvdata(&i2c->dev);
+
+	madera_dev_exit(madera);
+}
+
+static const struct i2c_device_id madera_i2c_id[] = {
+	{ "cs47l15", CS47L15 },
+	{ "cs47l35", CS47L35 },
+	{ "cs47l85", CS47L85 },
+	{ "cs47l90", CS47L90 },
+	{ "cs47l91", CS47L91 },
+	{ "cs42l92", CS42L92 },
+	{ "cs47l92", CS47L92 },
+	{ "cs47l93", CS47L93 },
+	{ "wm1840", WM1840 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, madera_i2c_id);
+
+static struct i2c_driver madera_i2c_driver = {
+	.driver = {
+		.name	= "madera",
+		.pm	= &madera_pm_ops,
+		.of_match_table	= of_match_ptr(madera_of_match),
+	},
+	.probe		= madera_i2c_probe,
+	.remove		= madera_i2c_remove,
+	.id_table	= madera_i2c_id,
+};
+
+module_i2c_driver(madera_i2c_driver);
+
+MODULE_DESCRIPTION("Madera I2C bus interface");
+MODULE_AUTHOR("Richard Fitzgerald <rf@opensource.cirrus.com>");
+MODULE_LICENSE("GPL v2");