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, 131 insertions, 0 deletions

diff --git a/sound/soc/sof/stream-ipc.c b/sound/soc/sof/stream-ipc.c
new file mode 100644
index 000000000..78758cf58
--- /dev/null
+++ b/sound/soc/sof/stream-ipc.c
@@ -0,0 +1,131 @@
+// 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) 2019 Intel Corporation
+//
+// Authors: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
+
+/* Generic SOF IPC code */
+
+#include <linux/device.h>
+#include <linux/export.h>
+#include <linux/module.h>
+#include <linux/types.h>
+
+#include <sound/pcm.h>
+#include <sound/sof/stream.h>
+
+#include "ops.h"
+#include "sof-priv.h"
+#include "sof-audio.h"
+
+struct sof_stream {
+	size_t posn_offset;
+};
+
+/* Mailbox-based Generic IPC implementation */
+int sof_ipc_msg_data(struct snd_sof_dev *sdev,
+		     struct snd_sof_pcm_stream *sps,
+		     void *p, size_t sz)
+{
+	if (!sps || !sdev->stream_box.size) {
+		snd_sof_dsp_mailbox_read(sdev, sdev->dsp_box.offset, p, sz);
+	} else {
+		size_t posn_offset;
+
+		if (sps->substream) {
+			struct sof_stream *stream = sps->substream->runtime->private_data;
+
+			/* The stream might already be closed */
+			if (!stream)
+				return -ESTRPIPE;
+
+			posn_offset = stream->posn_offset;
+		} else if (sps->cstream) {
+
+			struct sof_compr_stream *sstream = sps->cstream->runtime->private_data;
+
+			if (!sstream)
+				return -ESTRPIPE;
+
+			posn_offset = sstream->posn_offset;
+
+		} else {
+			dev_err(sdev->dev, "%s: No stream opened\n", __func__);
+			return -EINVAL;
+		}
+
+		snd_sof_dsp_mailbox_read(sdev, posn_offset, p, sz);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(sof_ipc_msg_data);
+
+int sof_set_stream_data_offset(struct snd_sof_dev *sdev,
+			       struct snd_sof_pcm_stream *sps,
+			       size_t posn_offset)
+{
+	/* check if offset is overflow or it is not aligned */
+	if (posn_offset > sdev->stream_box.size ||
+	    posn_offset % sizeof(struct sof_ipc_stream_posn) != 0)
+		return -EINVAL;
+
+	posn_offset += sdev->stream_box.offset;
+
+	if (sps->substream) {
+		struct sof_stream *stream = sps->substream->runtime->private_data;
+
+		stream->posn_offset = posn_offset;
+		dev_dbg(sdev->dev, "pcm: stream dir %d, posn mailbox offset is %zu",
+			sps->substream->stream, posn_offset);
+	} else if (sps->cstream) {
+		struct sof_compr_stream *sstream = sps->cstream->runtime->private_data;
+
+		sstream->posn_offset = posn_offset;
+		dev_dbg(sdev->dev, "compr: stream dir %d, posn mailbox offset is %zu",
+			sps->cstream->direction, posn_offset);
+	} else {
+		dev_err(sdev->dev, "No stream opened");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(sof_set_stream_data_offset);
+
+int sof_stream_pcm_open(struct snd_sof_dev *sdev,
+			struct snd_pcm_substream *substream)
+{
+	struct sof_stream *stream = kmalloc_obj(*stream);
+
+	if (!stream)
+		return -ENOMEM;
+
+	/* binding pcm substream to hda stream */
+	substream->runtime->private_data = stream;
+
+	/* align to DMA minimum transfer size */
+	snd_pcm_hw_constraint_step(substream->runtime, 0, SNDRV_PCM_HW_PARAM_PERIOD_BYTES, 4);
+
+	/* avoid circular buffer wrap in middle of period */
+	snd_pcm_hw_constraint_integer(substream->runtime,
+				      SNDRV_PCM_HW_PARAM_PERIODS);
+
+	return 0;
+}
+EXPORT_SYMBOL(sof_stream_pcm_open);
+
+int sof_stream_pcm_close(struct snd_sof_dev *sdev,
+			 struct snd_pcm_substream *substream)
+{
+	struct sof_stream *stream = substream->runtime->private_data;
+
+	substream->runtime->private_data = NULL;
+	kfree(stream);
+
+	return 0;
+}
+EXPORT_SYMBOL(sof_stream_pcm_close);