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, 44 insertions, 0 deletions

diff --git a/drivers/sh/intc/Kconfig b/drivers/sh/intc/Kconfig
new file mode 100644
index 000000000..5c701709f
--- /dev/null
+++ b/drivers/sh/intc/Kconfig
@@ -0,0 +1,44 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config SH_INTC
+	bool
+	select IRQ_DOMAIN
+
+if SH_INTC
+
+comment "Interrupt controller options"
+
+config INTC_USERIMASK
+	bool "Userspace interrupt masking support"
+	depends on (SUPERH && CPU_SH4A) || COMPILE_TEST
+	help
+	  This enables support for hardware-assisted userspace hardirq
+	  masking.
+
+	  SH-4A and newer interrupt blocks all support a special shadowed
+	  page with all non-masking registers obscured when mapped in to
+	  userspace. This is primarily for use by userspace device
+	  drivers that are using special priority levels.
+
+	  If in doubt, say N.
+
+config INTC_BALANCING
+	bool "Hardware IRQ balancing support"
+	depends on SMP && SUPERH && CPU_SHX3
+	help
+	  This enables support for IRQ auto-distribution mode on SH-X3
+	  SMP parts. All of the balancing and CPU wakeup decisions are
+	  taken care of automatically by hardware for distributed
+	  vectors.
+
+	  If in doubt, say N.
+
+config INTC_MAPPING_DEBUG
+	bool "Expose IRQ to per-controller id mapping via debugfs"
+	depends on DEBUG_FS
+	help
+	  This will create a debugfs entry for showing the relationship
+	  between system IRQs and the per-controller id tables.
+
+	  If in doubt, say N.
+
+endif