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, 55 insertions, 0 deletions

diff --git a/drivers/iio/buffer/Kconfig b/drivers/iio/buffer/Kconfig
new file mode 100644
index 000000000..047b93159
--- /dev/null
+++ b/drivers/iio/buffer/Kconfig
@@ -0,0 +1,55 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Industrial I/O generic buffer implementations
+#
+# When adding new entries keep the list in alphabetical order
+
+config IIO_BUFFER_CB
+	tristate "IIO callback buffer used for push in-kernel interfaces"
+	help
+	  Should be selected by any drivers that do in-kernel push
+	  usage.  That is, those where the data is pushed to the consumer.
+
+config IIO_BUFFER_DMA
+	tristate "Industrial I/O DMA buffer infrastructure"
+	help
+	  Provides the generic IIO DMA buffer infrastructure that can be used by
+	  drivers for devices with DMA support to implement the IIO buffer.
+
+	  Should be selected by drivers that want to use the generic DMA buffer
+	  infrastructure.
+
+config IIO_BUFFER_DMAENGINE
+	tristate "Industrial I/O DMA buffer integration with DMAEngine"
+	select IIO_BUFFER_DMA
+	help
+	  Provides a bonding of the generic IIO DMA buffer infrastructure with the
+	  DMAEngine framework. This can be used by converter drivers with a DMA port
+	  connected to an external DMA controller which is supported by the
+	  DMAEngine framework.
+
+	  Should be selected by drivers that want to use this functionality.
+
+config IIO_BUFFER_HW_CONSUMER
+	tristate "Industrial I/O HW buffering"
+	help
+	  Provides a way to bonding when an IIO device has a direct connection
+	  to another device in hardware. In this case buffers for data transfers
+	  are handled by hardware.
+
+	  Should be selected by drivers that want to use the generic Hw consumer
+	  interface.
+
+config IIO_KFIFO_BUF
+	tristate "Industrial I/O buffering based on kfifo"
+	help
+	  A simple fifo based on kfifo.  Note that this currently provides
+	  no buffer events so it is up to userspace to work out how
+	  often to read from the buffer.
+
+config IIO_TRIGGERED_BUFFER
+	tristate "Industrial I/O triggered buffer support"
+	select IIO_TRIGGER
+	select IIO_KFIFO_BUF
+	help
+	  Provides helper functions for setting up triggered buffers.