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, 215 insertions, 0 deletions

diff --git a/sound/soc/codecs/dmic.c b/sound/soc/codecs/dmic.c
new file mode 100644
index 000000000..cbed11136
--- /dev/null
+++ b/sound/soc/codecs/dmic.c
@@ -0,0 +1,215 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * dmic.c  --  SoC audio for Generic Digital MICs
+ *
+ * Author: Liam Girdwood <lrg@slimlogic.co.uk>
+ */
+
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include <sound/soc.h>
+#include <sound/soc-dapm.h>
+
+#define MAX_MODESWITCH_DELAY 70
+static int modeswitch_delay;
+module_param(modeswitch_delay, uint, 0644);
+
+static int wakeup_delay;
+module_param(wakeup_delay, uint, 0644);
+
+struct dmic {
+	struct gpio_desc *gpio_en;
+	struct regulator *vref;
+	int wakeup_delay;
+	/* Delay after DMIC mode switch */
+	int modeswitch_delay;
+};
+
+static int dmic_daiops_trigger(struct snd_pcm_substream *substream,
+			       int cmd, struct snd_soc_dai *dai)
+{
+	struct snd_soc_component *component = dai->component;
+	struct dmic *dmic = snd_soc_component_get_drvdata(component);
+
+	switch (cmd) {
+	case SNDRV_PCM_TRIGGER_STOP:
+		if (dmic->modeswitch_delay)
+			mdelay(dmic->modeswitch_delay);
+
+		break;
+	}
+
+	return 0;
+}
+
+static const struct snd_soc_dai_ops dmic_dai_ops = {
+	.trigger	= dmic_daiops_trigger,
+};
+
+static int dmic_aif_event(struct snd_soc_dapm_widget *w,
+			  struct snd_kcontrol *kcontrol, int event) {
+	struct snd_soc_component *component = snd_soc_dapm_to_component(w->dapm);
+	struct dmic *dmic = snd_soc_component_get_drvdata(component);
+	int ret = 0;
+
+	switch (event) {
+	case SND_SOC_DAPM_POST_PMU:
+		if (dmic->gpio_en)
+			gpiod_set_value_cansleep(dmic->gpio_en, 1);
+
+		if (dmic->vref) {
+			ret = regulator_enable(dmic->vref);
+			if (ret)
+				return ret;
+		}
+
+		if (dmic->wakeup_delay)
+			msleep(dmic->wakeup_delay);
+		break;
+	case SND_SOC_DAPM_POST_PMD:
+		if (dmic->gpio_en)
+			gpiod_set_value_cansleep(dmic->gpio_en, 0);
+
+		if (dmic->vref)
+			ret = regulator_disable(dmic->vref);
+
+		break;
+	}
+
+	return ret;
+}
+
+static struct snd_soc_dai_driver dmic_dai = {
+	.name = "dmic-hifi",
+	.capture = {
+		.stream_name = "Capture",
+		.channels_min = 1,
+		.channels_max = 8,
+		.rates = SNDRV_PCM_RATE_CONTINUOUS,
+		.formats = SNDRV_PCM_FMTBIT_S32_LE
+			| SNDRV_PCM_FMTBIT_S24_LE
+			| SNDRV_PCM_FMTBIT_S16_LE
+			| SNDRV_PCM_FMTBIT_DSD_U8
+			| SNDRV_PCM_FMTBIT_DSD_U16_LE
+			| SNDRV_PCM_FMTBIT_DSD_U32_LE
+			| SNDRV_PCM_FMTBIT_DSD_U16_BE
+			| SNDRV_PCM_FMTBIT_DSD_U32_BE,
+	},
+	.ops    = &dmic_dai_ops,
+};
+
+static int dmic_component_probe(struct snd_soc_component *component)
+{
+	struct dmic *dmic;
+
+	dmic = devm_kzalloc(component->dev, sizeof(*dmic), GFP_KERNEL);
+	if (!dmic)
+		return -ENOMEM;
+
+	dmic->vref = devm_regulator_get_optional(component->dev, "vref");
+	if (IS_ERR(dmic->vref)) {
+		if (PTR_ERR(dmic->vref) != -ENODEV)
+			return dev_err_probe(component->dev, PTR_ERR(dmic->vref),
+					     "Failed to get vref\n");
+		dmic->vref = NULL;
+	}
+
+	dmic->gpio_en = devm_gpiod_get_optional(component->dev,
+						"dmicen", GPIOD_OUT_LOW);
+	if (IS_ERR(dmic->gpio_en))
+		return PTR_ERR(dmic->gpio_en);
+
+	device_property_read_u32(component->dev, "wakeup-delay-ms",
+				 &dmic->wakeup_delay);
+	device_property_read_u32(component->dev, "modeswitch-delay-ms",
+				 &dmic->modeswitch_delay);
+	if (wakeup_delay)
+		dmic->wakeup_delay  = wakeup_delay;
+	if (modeswitch_delay)
+		dmic->modeswitch_delay  = modeswitch_delay;
+
+	if (dmic->modeswitch_delay > MAX_MODESWITCH_DELAY)
+		dmic->modeswitch_delay = MAX_MODESWITCH_DELAY;
+
+	snd_soc_component_set_drvdata(component, dmic);
+
+	return 0;
+}
+
+static const struct snd_soc_dapm_widget dmic_dapm_widgets[] = {
+	SND_SOC_DAPM_AIF_OUT_E("DMIC AIF", "Capture", 0,
+			       SND_SOC_NOPM, 0, 0, dmic_aif_event,
+			       SND_SOC_DAPM_POST_PMU | SND_SOC_DAPM_POST_PMD),
+	SND_SOC_DAPM_INPUT("DMic"),
+};
+
+static const struct snd_soc_dapm_route intercon[] = {
+	{"DMIC AIF", NULL, "DMic"},
+};
+
+static const struct snd_soc_component_driver soc_dmic = {
+	.probe			= dmic_component_probe,
+	.dapm_widgets		= dmic_dapm_widgets,
+	.num_dapm_widgets	= ARRAY_SIZE(dmic_dapm_widgets),
+	.dapm_routes		= intercon,
+	.num_dapm_routes	= ARRAY_SIZE(intercon),
+	.idle_bias_on		= 1,
+	.use_pmdown_time	= 1,
+	.endianness		= 1,
+};
+
+static int dmic_dev_probe(struct platform_device *pdev)
+{
+	int err;
+	u32 chans;
+	struct snd_soc_dai_driver *dai_drv = &dmic_dai;
+
+	if (pdev->dev.of_node) {
+		err = of_property_read_u32(pdev->dev.of_node, "num-channels", &chans);
+		if (err && (err != -EINVAL))
+			return err;
+
+		if (!err) {
+			if (chans < 1 || chans > 8)
+				return -EINVAL;
+
+			dai_drv = devm_kzalloc(&pdev->dev, sizeof(*dai_drv), GFP_KERNEL);
+			if (!dai_drv)
+				return -ENOMEM;
+
+			memcpy(dai_drv, &dmic_dai, sizeof(*dai_drv));
+			dai_drv->capture.channels_max = chans;
+		}
+	}
+
+	return devm_snd_soc_register_component(&pdev->dev,
+			&soc_dmic, dai_drv, 1);
+}
+
+MODULE_ALIAS("platform:dmic-codec");
+
+static const struct of_device_id dmic_dev_match[] = {
+	{.compatible = "dmic-codec"},
+	{}
+};
+MODULE_DEVICE_TABLE(of, dmic_dev_match);
+
+static struct platform_driver dmic_driver = {
+	.driver = {
+		.name = "dmic-codec",
+		.of_match_table = dmic_dev_match,
+	},
+	.probe = dmic_dev_probe,
+};
+
+module_platform_driver(dmic_driver);
+
+MODULE_DESCRIPTION("Generic DMIC driver");
+MODULE_AUTHOR("Liam Girdwood <lrg@slimlogic.co.uk>");
+MODULE_LICENSE("GPL");