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, 56 insertions, 0 deletions

diff --git a/drivers/soc/aspeed/Kconfig b/drivers/soc/aspeed/Kconfig
new file mode 100644
index 000000000..63a656449
--- /dev/null
+++ b/drivers/soc/aspeed/Kconfig
@@ -0,0 +1,56 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+if ARCH_ASPEED || COMPILE_TEST
+
+menu "ASPEED SoC drivers"
+
+config ASPEED_LPC_CTRL
+	tristate "ASPEED LPC firmware cycle control"
+	select REGMAP
+	select MFD_SYSCON
+	default ARCH_ASPEED
+	help
+	  Control LPC firmware cycle mappings through ioctl()s. The driver
+	  also provides a read/write interface to a BMC ram region where the
+	  host LPC read/write region can be buffered.
+
+config ASPEED_LPC_SNOOP
+	tristate "ASPEED LPC snoop support"
+	select REGMAP
+	select MFD_SYSCON
+	default ARCH_ASPEED
+	help
+	  Provides a driver to control the LPC snoop interface which
+	  allows the BMC to listen on and save the data written by
+	  the host to an arbitrary LPC I/O port.
+
+config ASPEED_UART_ROUTING
+	tristate "ASPEED uart routing control"
+	select REGMAP
+	select MFD_SYSCON
+	default ARCH_ASPEED
+	help
+	  Provides a driver to control the UART routing paths, allowing
+	  users to perform runtime configuration of the RX muxes among
+	  the UART controllers and I/O pins.
+
+config ASPEED_P2A_CTRL
+	tristate "ASPEED P2A (VGA MMIO to BMC) bridge control"
+	select REGMAP
+	select MFD_SYSCON
+	default ARCH_ASPEED
+	help
+	  Control ASPEED P2A VGA MMIO to BMC mappings through ioctl()s.  The
+	  driver also provides an interface for userspace mappings to a
+	  pre-defined region.
+
+config ASPEED_SOCINFO
+	bool "ASPEED SoC Information driver"
+	select SOC_BUS
+	default ARCH_ASPEED
+	help
+	  Say yes to support decoding of ASPEED BMC information.
+
+endmenu
+
+endif