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, 68 insertions, 0 deletions

diff --git a/drivers/usb/atm/Kconfig b/drivers/usb/atm/Kconfig
new file mode 100644
index 000000000..3d958a1a1
--- /dev/null
+++ b/drivers/usb/atm/Kconfig
@@ -0,0 +1,68 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# USB/ATM DSL configuration
+#
+
+menuconfig USB_ATM
+	tristate "USB DSL modem support"
+	depends on ATM
+	select CRC32
+	help
+	  Say Y here if you want to connect a USB Digital Subscriber Line (DSL)
+	  modem to your computer's USB port.  You will then need to choose your
+	  modem from the list below.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called usbatm.
+
+if USB_ATM
+
+config USB_SPEEDTOUCH
+	tristate "Speedtouch USB support"
+	select FW_LOADER
+	help
+	  Say Y here if you have an SpeedTouch USB or SpeedTouch 330
+	  modem.  In order to use your modem you will need to install the 
+	  two parts of the firmware, extracted by the user space tools; see
+	  <http://www.linux-usb.org/SpeedTouch/> for details.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called speedtch.
+
+config USB_CXACRU
+	tristate "Conexant AccessRunner USB support"
+	select FW_LOADER
+	help
+	  Say Y here if you have an ADSL USB modem based on the Conexant
+	  AccessRunner chipset.  In order to use your modem you will need to
+	  install the firmware, extracted by the user space tools; see
+	  <http://accessrunner.sourceforge.net/> for details.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called cxacru.
+
+config USB_UEAGLEATM
+	tristate "ADI 930 and eagle USB DSL modem"
+	select FW_LOADER
+	help
+	  Say Y here if you have an ADSL USB modem based on the ADI 930
+	  or eagle chipset. In order to use your modem you will need to
+	  install firmwares and CMV (Command Management Variables); see
+	  <https://gna.org/projects/ueagleatm/> for details.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ueagle-atm.
+
+config USB_XUSBATM
+	tristate "Other USB DSL modem support"
+	help
+	  Say Y here if you have a DSL USB modem not explicitly supported by
+	  another USB DSL drivers.  In order to use your modem you will need to
+	  pass the vendor ID, product ID, and endpoint numbers for transmission
+	  and reception as module parameters.  You may need to initialize
+	  the modem using a user space utility (a firmware loader for example).
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called xusbatm.
+
+endif # USB_ATM