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, 171 insertions, 0 deletions

diff --git a/sound/soc/codecs/max9877.c b/sound/soc/codecs/max9877.c
new file mode 100644
index 000000000..7cd07b6f9
--- /dev/null
+++ b/sound/soc/codecs/max9877.c
@@ -0,0 +1,171 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * max9877.c  --  amp driver for max9877
+ *
+ * Copyright (C) 2009 Samsung Electronics Co.Ltd
+ * Author: Joonyoung Shim <jy0922.shim@samsung.com>
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+#include <linux/regmap.h>
+#include <sound/soc.h>
+#include <sound/tlv.h>
+
+#include "max9877.h"
+
+static const struct reg_default max9877_regs[] = {
+	{ 0, 0x40 },
+	{ 1, 0x00 },
+	{ 2, 0x00 },
+	{ 3, 0x00 },
+	{ 4, 0x49 },
+};
+
+static const DECLARE_TLV_DB_RANGE(max9877_pgain_tlv,
+	0, 1, TLV_DB_SCALE_ITEM(0, 900, 0),
+	2, 2, TLV_DB_SCALE_ITEM(2000, 0, 0)
+);
+
+static const DECLARE_TLV_DB_RANGE(max9877_output_tlv,
+	0, 7, TLV_DB_SCALE_ITEM(-7900, 400, 1),
+	8, 15, TLV_DB_SCALE_ITEM(-4700, 300, 0),
+	16, 23, TLV_DB_SCALE_ITEM(-2300, 200, 0),
+	24, 31, TLV_DB_SCALE_ITEM(-700, 100, 0)
+);
+
+static const char *max9877_out_mode[] = {
+	"INA -> SPK",
+	"INA -> HP",
+	"INA -> SPK and HP",
+	"INB -> SPK",
+	"INB -> HP",
+	"INB -> SPK and HP",
+	"INA + INB -> SPK",
+	"INA + INB -> HP",
+	"INA + INB -> SPK and HP",
+};
+
+static const char *max9877_osc_mode[] = {
+	"1176KHz",
+	"1100KHz",
+	"700KHz",
+};
+
+static const struct soc_enum max9877_enum[] = {
+	SOC_ENUM_SINGLE(MAX9877_OUTPUT_MODE, 0, ARRAY_SIZE(max9877_out_mode),
+			max9877_out_mode),
+	SOC_ENUM_SINGLE(MAX9877_OUTPUT_MODE, MAX9877_OSC_OFFSET,
+			ARRAY_SIZE(max9877_osc_mode), max9877_osc_mode),
+};
+
+static const struct snd_kcontrol_new max9877_controls[] = {
+	SOC_SINGLE_TLV("MAX9877 PGAINA Playback Volume",
+		       MAX9877_INPUT_MODE, 0, 2, 0, max9877_pgain_tlv),
+	SOC_SINGLE_TLV("MAX9877 PGAINB Playback Volume",
+		       MAX9877_INPUT_MODE, 2, 2, 0, max9877_pgain_tlv),
+	SOC_SINGLE_TLV("MAX9877 Amp Speaker Playback Volume",
+		       MAX9877_SPK_VOLUME, 0, 31, 0, max9877_output_tlv),
+	SOC_DOUBLE_R_TLV("MAX9877 Amp HP Playback Volume",
+			 MAX9877_HPL_VOLUME, MAX9877_HPR_VOLUME, 0, 31, 0,
+			 max9877_output_tlv),
+	SOC_SINGLE("MAX9877 INB Stereo Switch",
+		   MAX9877_INPUT_MODE, 4, 1, 1),
+	SOC_SINGLE("MAX9877 INA Stereo Switch",
+		   MAX9877_INPUT_MODE, 5, 1, 1),
+	SOC_SINGLE("MAX9877 Zero-crossing detection Switch",
+		   MAX9877_INPUT_MODE, 6, 1, 0),
+	SOC_SINGLE("MAX9877 Bypass Mode Switch",
+		   MAX9877_OUTPUT_MODE, 6, 1, 0),
+	SOC_ENUM("MAX9877 Output Mode", max9877_enum[0]),
+	SOC_ENUM("MAX9877 Oscillator Mode", max9877_enum[1]),
+};
+
+static const struct snd_soc_dapm_widget max9877_dapm_widgets[] = {
+SND_SOC_DAPM_INPUT("INA1"),
+SND_SOC_DAPM_INPUT("INA2"),
+SND_SOC_DAPM_INPUT("INB1"),
+SND_SOC_DAPM_INPUT("INB2"),
+SND_SOC_DAPM_INPUT("RXIN+"),
+SND_SOC_DAPM_INPUT("RXIN-"),
+
+SND_SOC_DAPM_PGA("SHDN", MAX9877_OUTPUT_MODE, 7, 1, NULL, 0),
+
+SND_SOC_DAPM_OUTPUT("OUT+"),
+SND_SOC_DAPM_OUTPUT("OUT-"),
+SND_SOC_DAPM_OUTPUT("HPL"),
+SND_SOC_DAPM_OUTPUT("HPR"),
+};
+
+static const struct snd_soc_dapm_route max9877_dapm_routes[] = {
+	{ "SHDN", NULL, "INA1" },
+	{ "SHDN", NULL, "INA2" },
+	{ "SHDN", NULL, "INB1" },
+	{ "SHDN", NULL, "INB2" },
+
+	{ "OUT+", NULL, "RXIN+" },
+	{ "OUT+", NULL, "SHDN" },
+
+	{ "OUT-", NULL, "SHDN" },
+	{ "OUT-", NULL, "RXIN-" },
+
+	{ "HPL", NULL, "SHDN" },
+	{ "HPR", NULL, "SHDN" },
+};
+
+static const struct snd_soc_component_driver max9877_component_driver = {
+	.controls = max9877_controls,
+	.num_controls = ARRAY_SIZE(max9877_controls),
+
+	.dapm_widgets = max9877_dapm_widgets,
+	.num_dapm_widgets = ARRAY_SIZE(max9877_dapm_widgets),
+	.dapm_routes = max9877_dapm_routes,
+	.num_dapm_routes = ARRAY_SIZE(max9877_dapm_routes),
+};
+
+static const struct regmap_config max9877_regmap = {
+	.reg_bits = 8,
+	.val_bits = 8,
+
+	.reg_defaults = max9877_regs,
+	.num_reg_defaults = ARRAY_SIZE(max9877_regs),
+	.cache_type = REGCACHE_RBTREE,
+};
+
+static int max9877_i2c_probe(struct i2c_client *client)
+{
+	struct regmap *regmap;
+	int i;
+
+	regmap = devm_regmap_init_i2c(client, &max9877_regmap);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	/* Ensure the device is in reset state */
+	for (i = 0; i < ARRAY_SIZE(max9877_regs); i++)
+		regmap_write(regmap, max9877_regs[i].reg, max9877_regs[i].def);
+
+	return devm_snd_soc_register_component(&client->dev,
+			&max9877_component_driver, NULL, 0);
+}
+
+static const struct i2c_device_id max9877_i2c_id[] = {
+	{ .name = "max9877" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, max9877_i2c_id);
+
+static struct i2c_driver max9877_i2c_driver = {
+	.driver = {
+		.name = "max9877",
+	},
+	.probe = max9877_i2c_probe,
+	.id_table = max9877_i2c_id,
+};
+
+module_i2c_driver(max9877_i2c_driver);
+
+MODULE_DESCRIPTION("ASoC MAX9877 amp driver");
+MODULE_AUTHOR("Joonyoung Shim <jy0922.shim@samsung.com>");
+MODULE_LICENSE("GPL");