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, 83 insertions, 0 deletions

diff --git a/drivers/net/pse-pd/Kconfig b/drivers/net/pse-pd/Kconfig
new file mode 100644
index 000000000..a0f2ae668
--- /dev/null
+++ b/drivers/net/pse-pd/Kconfig
@@ -0,0 +1,83 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Ethernet Power Sourcing Equipment drivers
+#
+
+menuconfig PSE_CONTROLLER
+	bool "Ethernet Power Sourcing Equipment Support"
+	depends on REGULATOR
+	help
+	  Generic Power Sourcing Equipment Controller support.
+
+	  If unsure, say no.
+
+if PSE_CONTROLLER
+
+config PSE_REALTEK_MCU
+	tristate
+	help
+	  Shared core for the Realtek PSE MCU driver. This is selected
+	  automatically by the transport options below.
+
+config PSE_REALTEK_MCU_I2C
+	tristate "Realtek PSE MCU driver (I2C transport)"
+	depends on I2C
+	select PSE_REALTEK_MCU
+	help
+	  Driver for the microcontroller (MCU) that fronts the PSE
+	  hardware on various Realtek-based managed switches, attached
+	  via I2C/SMBus. The MCU exposes a message-based protocol; the actual
+	  PSE silicon is not accessed directly. To compile this driver as a
+	  module, choose M here: the module will be called realtek-pse-mcu-i2c.
+
+config PSE_REALTEK_MCU_UART
+	tristate "Realtek PSE MCU driver (UART transport)"
+	depends on SERIAL_DEV_BUS
+	select PSE_REALTEK_MCU
+	help
+	  Driver for the microcontroller (MCU) that fronts the PSE
+	  hardware on various Realtek-based managed switches, attached
+	  via UART. The MCU exposes a message-based protocol; the actual PSE
+	  silicon is not accessed directly. To compile this driver as a
+	  module, choose M here: the module will be called realtek-pse-mcu-uart.
+
+config PSE_REGULATOR
+	tristate "Regulator based PSE controller"
+	help
+	  This module provides support for simple regulator based Ethernet Power
+	  Sourcing Equipment without automatic classification support. For
+	  example for basic implementation of PoDL (802.3bu) specification.
+
+config PSE_PD692X0
+	tristate "PD692X0 PSE controller"
+	depends on I2C
+	select FW_LOADER
+	select FW_UPLOAD
+	help
+	  This module provides support for PD692x0 regulator based Ethernet
+	  Power Sourcing Equipment.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called pd692x0.
+
+config PSE_SI3474
+	tristate "Si3474 PSE controller"
+	depends on I2C
+	help
+	  This module provides support for Si3474 regulator based Ethernet
+	  Power Sourcing Equipment.
+	  Only 4-pair PSE configurations are supported.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called si3474.
+
+config PSE_TPS23881
+	tristate "TPS23881 PSE controller"
+	depends on I2C
+	help
+	  This module provides support for TPS23881 regulator based Ethernet
+	  Power Sourcing Equipment.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called tps23881.
+endif