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, 60 insertions, 0 deletions

diff --git a/sound/soc/codecs/cs4265.h b/sound/soc/codecs/cs4265.h
new file mode 100644
index 000000000..8bc28c2bf
--- /dev/null
+++ b/sound/soc/codecs/cs4265.h
@@ -0,0 +1,60 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * cs4265.h -- CS4265 ALSA SoC audio driver
+ *
+ * Copyright 2014 Cirrus Logic, Inc.
+ *
+ * Author: Paul Handrigan <paul.handrigan@cirrus.com>
+ */
+
+#ifndef __CS4265_H__
+#define __CS4265_H__
+
+#define CS4265_CHIP_ID				0x1
+#define CS4265_CHIP_ID_VAL			0xD0
+#define CS4265_CHIP_ID_MASK			0xF0
+#define CS4265_REV_ID_MASK			0x0F
+
+#define CS4265_PWRCTL				0x02
+#define CS4265_PWRCTL_PDN			1
+
+#define CS4265_DAC_CTL				0x3
+#define CS4265_DAC_CTL_MUTE			(1 << 2)
+#define CS4265_DAC_CTL_DIF			(3 << 4)
+
+#define CS4265_ADC_CTL				0x4
+#define CS4265_ADC_MASTER			1
+#define CS4265_ADC_DIF				(1 << 4)
+#define CS4265_ADC_FM				(3 << 6)
+
+#define CS4265_MCLK_FREQ			0x5
+#define CS4265_MCLK_FREQ_MASK			(7 << 4)
+
+#define CS4265_SIG_SEL				0x6
+#define CS4265_SIG_SEL_LOOP			(1 << 1)
+
+#define CS4265_CHB_PGA_CTL			0x7
+#define CS4265_CHA_PGA_CTL			0x8
+
+#define CS4265_ADC_CTL2				0x9
+
+#define CS4265_DAC_CHA_VOL			0xA
+#define CS4265_DAC_CHB_VOL			0xB
+
+#define CS4265_DAC_CTL2				0xC
+
+#define CS4265_INT_STATUS			0xD
+#define CS4265_INT_MASK				0xE
+#define CS4265_STATUS_MODE_MSB			0xF
+#define CS4265_STATUS_MODE_LSB			0x10
+
+#define CS4265_SPDIF_CTL1			0x11
+
+#define CS4265_SPDIF_CTL2			0x12
+#define CS4265_SPDIF_CTL2_MUTE			(1 << 4)
+#define CS4265_SPDIF_CTL2_DIF			(3 << 6)
+
+#define CS4265_C_DATA_BUFF			0x13
+#define CS4265_MAX_REGISTER			0x2A
+
+#endif