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, 92 insertions, 0 deletions

diff --git a/drivers/s390/net/Kconfig b/drivers/s390/net/Kconfig
new file mode 100644
index 000000000..0fd700c57
--- /dev/null
+++ b/drivers/s390/net/Kconfig
@@ -0,0 +1,92 @@
+# SPDX-License-Identifier: GPL-2.0
+menu "S/390 network device drivers"
+	depends on NETDEVICES && S390
+
+config CTCM
+	def_tristate m
+	prompt "CTC and MPC SNA device support"
+	depends on CCW && NETDEVICES
+	help
+	  Select this option if you want to use channel-to-channel
+	  point-to-point networking on IBM System z.
+	  This device driver supports real CTC coupling using ESCON.
+	  It also supports virtual CTCs when running under VM.
+	  This driver also supports channel-to-channel MPC SNA devices.
+	  MPC is an SNA protocol device used by Communication Server for Linux.
+	  To compile as a module, choose M. The module name is ctcm.
+	  To compile into the kernel, choose Y.
+	  If you do not need any channel-to-channel connection, choose N.
+
+config SMSGIUCV
+	def_tristate m
+	prompt "IUCV special message support (VM only)"
+	depends on IUCV
+	help
+	  Select this option if you want to be able to receive SMSG messages
+	  from other VM guest systems.
+
+config SMSGIUCV_EVENT
+	def_tristate m
+	prompt "Deliver IUCV special messages as uevents (VM only)"
+	depends on SMSGIUCV
+	help
+	  Select this option to deliver CP special messages (SMSGs) as
+	  uevents.  The driver handles only those special messages that
+	  start with "APP".
+
+	  To compile as a module, choose M. The module name is "smsgiucv_app".
+
+config QETH
+	def_tristate y
+	prompt "Gigabit Ethernet device support"
+	depends on CCW && NETDEVICES && IP_MULTICAST && QDIO && ETHERNET
+	help
+	  This driver supports IBM's OSA Express network adapters in QDIO mode,
+	  HiperSockets interfaces and z/VM virtual NICs for Guest LAN and
+	  VSWITCH.
+
+	  To compile this driver as a module, choose M.
+	  The module name is qeth.
+
+config QETH_L2
+	def_tristate y
+	prompt "qeth layer 2 device support"
+	depends on QETH
+	depends on BRIDGE || BRIDGE=n
+	help
+	  Select this option to be able to run qeth devices in layer 2 mode.
+	  To compile as a module, choose M. The module name is qeth_l2.
+	  If unsure, choose y.
+
+config QETH_L3
+	def_tristate y
+	prompt "qeth layer 3 device support"
+	depends on QETH
+	help
+	  Select this option to be able to run qeth devices in layer 3 mode.
+	  To compile as a module choose M. The module name is qeth_l3.
+	  If unsure, choose Y.
+
+config QETH_OSX
+	def_bool !HAVE_MARCH_Z15_FEATURES
+	prompt "qeth OSX device support"
+	depends on QETH
+	help
+	  This enables the qeth driver to support devices in OSX mode.
+	  If unsure, choose N.
+
+config CCWGROUP
+	tristate
+	default (CTCM || QETH || SMC)
+
+config ISM
+	tristate "Support for ISM vPCI Adapter"
+	depends on PCI && DIBS
+	default n
+	help
+	  Select this option if you want to use the Internal Shared Memory
+	  vPCI Adapter. The adapter can be used with the SMC network protocol.
+
+	  To compile as a module choose M. The module name is ism.
+	  If unsure, choose N.
+endmenu