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, 72 insertions, 0 deletions

diff --git a/sound/soc/sof/sof-client-probes.h b/sound/soc/sof/sof-client-probes.h
new file mode 100644
index 000000000..47d0582b8
--- /dev/null
+++ b/sound/soc/sof/sof-client-probes.h
@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef __SOF_CLIENT_PROBES_H
+#define __SOF_CLIENT_PROBES_H
+
+struct snd_compr_stream;
+struct snd_compr_tstamp64;
+struct snd_compr_params;
+struct sof_client_dev;
+struct snd_soc_dai;
+
+/*
+ * Callbacks used on platforms where the control for audio is split between
+ * DSP and host, like HDA.
+ */
+struct sof_probes_host_ops {
+	int (*startup)(struct sof_client_dev *cdev, struct snd_compr_stream *cstream,
+		       struct snd_soc_dai *dai, u32 *stream_id);
+	int (*shutdown)(struct sof_client_dev *cdev, struct snd_compr_stream *cstream,
+			struct snd_soc_dai *dai);
+	int (*set_params)(struct sof_client_dev *cdev, struct snd_compr_stream *cstream,
+			  struct snd_compr_params *params,
+			  struct snd_soc_dai *dai);
+	int (*trigger)(struct sof_client_dev *cdev, struct snd_compr_stream *cstream,
+		       int cmd, struct snd_soc_dai *dai);
+	int (*pointer)(struct sof_client_dev *cdev, struct snd_compr_stream *cstream,
+		       struct snd_compr_tstamp64 *tstamp,
+		       struct snd_soc_dai *dai);
+};
+
+struct sof_probe_point_desc {
+	unsigned int buffer_id;
+	unsigned int purpose;
+	unsigned int stream_tag;
+} __packed;
+
+enum sof_probe_info_type {
+	PROBES_INFO_ACTIVE_PROBES,
+	PROBES_INFO_AVAILABE_PROBES,
+};
+
+struct sof_probes_ipc_ops {
+	int (*init)(struct sof_client_dev *cdev, u32 stream_tag,
+		    size_t buffer_size);
+	int (*deinit)(struct sof_client_dev *cdev);
+	int (*points_info)(struct sof_client_dev *cdev,
+			   struct sof_probe_point_desc **desc,
+			   size_t *num_desc, enum sof_probe_info_type type);
+	int (*point_print)(struct sof_client_dev *cdev, char *buf, size_t size,
+			   struct sof_probe_point_desc *desc);
+	int (*points_add)(struct sof_client_dev *cdev,
+			  struct sof_probe_point_desc *desc,
+			  size_t num_desc);
+	int (*points_remove)(struct sof_client_dev *cdev,
+			     unsigned int *buffer_id, size_t num_buffer_id);
+};
+
+extern const struct sof_probes_ipc_ops ipc3_probe_ops;
+extern const struct sof_probes_ipc_ops ipc4_probe_ops;
+
+struct sof_probes_priv {
+	struct dentry *dfs_points;
+	struct dentry *dfs_points_remove;
+	u32 extractor_stream_tag;
+	struct snd_soc_card card;
+	void *ipc_priv;
+
+	const struct sof_probes_host_ops *host_ops;
+	const struct sof_probes_ipc_ops *ipc_ops;
+};
+
+#endif