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, 115 insertions, 0 deletions

diff --git a/sound/soc/sof/nocodec.c b/sound/soc/sof/nocodec.c
new file mode 100644
index 000000000..34744f8ae
--- /dev/null
+++ b/sound/soc/sof/nocodec.c
@@ -0,0 +1,115 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause)
+//
+// This file is provided under a dual BSD/GPLv2 license.  When using or
+// redistributing this file, you may do so under either license.
+//
+// Copyright(c) 2018 Intel Corporation
+//
+// Author: Liam Girdwood <liam.r.girdwood@linux.intel.com>
+//
+
+#include <linux/module.h>
+#include <sound/sof.h>
+#include "sof-audio.h"
+#include "sof-priv.h"
+
+static struct snd_soc_card sof_nocodec_card = {
+	.name = "nocodec", /* the sof- prefix is added by the core */
+	.owner = THIS_MODULE
+};
+
+static int sof_nocodec_bes_setup(struct device *dev,
+				 struct snd_soc_dai_driver *drv,
+				 struct snd_soc_dai_link *links,
+				 int link_num)
+{
+	struct snd_soc_card *card = &sof_nocodec_card;
+	struct snd_soc_dai_link_component *dlc;
+	int i;
+
+	if (!drv || !links)
+		return -EINVAL;
+
+	/* set up BE dai_links */
+	for (i = 0; i < link_num; i++) {
+		dlc = devm_kcalloc(dev, 2, sizeof(*dlc), GFP_KERNEL);
+		if (!dlc)
+			return -ENOMEM;
+
+		links[i].name = devm_kasprintf(dev, GFP_KERNEL,
+					       "NoCodec-%d", i);
+		if (!links[i].name)
+			return -ENOMEM;
+
+		links[i].stream_name = links[i].name;
+
+		links[i].cpus = &dlc[0];
+		links[i].codecs = &snd_soc_dummy_dlc;
+		links[i].platforms = &dlc[1];
+
+		links[i].num_cpus = 1;
+		links[i].num_codecs = 1;
+		links[i].num_platforms = 1;
+
+		links[i].id = i;
+		links[i].no_pcm = 1;
+		links[i].cpus->dai_name = drv[i].name;
+		links[i].platforms->name = dev_name(dev->parent);
+
+		links[i].playback_only =  drv[i].playback.channels_min && !drv[i].capture.channels_min;
+		links[i].capture_only  = !drv[i].playback.channels_min &&  drv[i].capture.channels_min;
+
+		links[i].be_hw_params_fixup = sof_pcm_dai_link_fixup;
+	}
+
+	card->dai_link = links;
+	card->num_links = link_num;
+
+	return 0;
+}
+
+static int sof_nocodec_setup(struct device *dev, struct snd_soc_acpi_mach *mach)
+{
+	u32 num_dai_drivers = mach->mach_params.num_dai_drivers;
+	struct snd_soc_dai_driver *dai_drivers = mach->mach_params.dai_drivers;
+	struct snd_soc_dai_link *links;
+
+	/* create dummy BE dai_links */
+	links = devm_kcalloc(dev, num_dai_drivers, sizeof(struct snd_soc_dai_link), GFP_KERNEL);
+	if (!links)
+		return -ENOMEM;
+
+	return sof_nocodec_bes_setup(dev, dai_drivers, links, num_dai_drivers);
+}
+
+static int sof_nocodec_probe(struct platform_device *pdev)
+{
+	struct snd_soc_card *card = &sof_nocodec_card;
+	struct snd_soc_acpi_mach *mach;
+	int ret;
+
+	card->dev = &pdev->dev;
+	mach = pdev->dev.platform_data;
+
+	snd_soc_card_set_topology_name(card, "sof");
+
+	ret = sof_nocodec_setup(card->dev, mach);
+	if (ret < 0)
+		return ret;
+
+	return devm_snd_soc_register_card(&pdev->dev, card);
+}
+
+static struct platform_driver sof_nocodec_audio = {
+	.probe = sof_nocodec_probe,
+	.driver = {
+		.name = "sof-nocodec",
+		.pm = &snd_soc_pm_ops,
+	},
+};
+module_platform_driver(sof_nocodec_audio)
+
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_DESCRIPTION("ASoC sof nocodec");
+MODULE_AUTHOR("Liam Girdwood");
+MODULE_ALIAS("platform:sof-nocodec");