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

6 files changed, 81 insertions, 0 deletions

diff --git a/arch/sh/include/cpu-common/cpu/addrspace.h b/arch/sh/include/cpu-common/cpu/addrspace.h
new file mode 100644
index 000000000..d8bf5d7d2
--- /dev/null
+++ b/arch/sh/include/cpu-common/cpu/addrspace.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * Definitions for the address spaces of the SH-2 CPUs.
+ *
+ * Copyright (C) 2003  Paul Mundt
+ */
+#ifndef __ASM_CPU_SH2_ADDRSPACE_H
+#define __ASM_CPU_SH2_ADDRSPACE_H
+
+#define P0SEG		0x00000000
+#define P1SEG		0x80000000
+#define P2SEG		0xa0000000
+#define P3SEG		0xc0000000
+#define P4SEG		0xe0000000
+
+#endif /* __ASM_CPU_SH2_ADDRSPACE_H */
diff --git a/arch/sh/include/cpu-common/cpu/mmu_context.h b/arch/sh/include/cpu-common/cpu/mmu_context.h
new file mode 100644
index 000000000..cef3a30db
--- /dev/null
+++ b/arch/sh/include/cpu-common/cpu/mmu_context.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * include/asm-sh/cpu-sh2/mmu_context.h
+ *
+ * Copyright (C) 2003  Paul Mundt
+ */
+#ifndef __ASM_CPU_SH2_MMU_CONTEXT_H
+#define __ASM_CPU_SH2_MMU_CONTEXT_H
+
+/* No MMU */
+
+#endif /* __ASM_CPU_SH2_MMU_CONTEXT_H */
+
diff --git a/arch/sh/include/cpu-common/cpu/pfc.h b/arch/sh/include/cpu-common/cpu/pfc.h
new file mode 100644
index 000000000..879d2c9da
--- /dev/null
+++ b/arch/sh/include/cpu-common/cpu/pfc.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * SH Pin Function Control Initialization
+ *
+ * Copyright (C) 2012  Renesas Solutions Corp.
+ */
+
+#ifndef __ARCH_SH_CPU_PFC_H__
+#define __ARCH_SH_CPU_PFC_H__
+
+#include <linux/types.h>
+
+struct resource;
+
+int sh_pfc_register(const char *name,
+		    struct resource *resource, u32 num_resources);
+
+#endif /* __ARCH_SH_CPU_PFC_H__ */
diff --git a/arch/sh/include/cpu-common/cpu/rtc.h b/arch/sh/include/cpu-common/cpu/rtc.h
new file mode 100644
index 000000000..5fe726acd
--- /dev/null
+++ b/arch/sh/include/cpu-common/cpu/rtc.h
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_SH_CPU_SH2_RTC_H
+#define __ASM_SH_CPU_SH2_RTC_H
+
+#define rtc_reg_size		sizeof(u16)
+#define RTC_BIT_INVERTED	0
+#define RTC_DEF_CAPABILITIES	0UL
+
+#endif /* __ASM_SH_CPU_SH2_RTC_H */
diff --git a/arch/sh/include/cpu-common/cpu/sigcontext.h b/arch/sh/include/cpu-common/cpu/sigcontext.h
new file mode 100644
index 000000000..e005dd176
--- /dev/null
+++ b/arch/sh/include/cpu-common/cpu/sigcontext.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_CPU_SH2_SIGCONTEXT_H
+#define __ASM_CPU_SH2_SIGCONTEXT_H
+
+struct sigcontext {
+	unsigned long	oldmask;
+
+	/* CPU registers */
+	unsigned long sc_regs[16];
+	unsigned long sc_pc;
+	unsigned long sc_pr;
+	unsigned long sc_sr;
+	unsigned long sc_gbr;
+	unsigned long sc_mach;
+	unsigned long sc_macl;
+};
+
+#endif /* __ASM_CPU_SH2_SIGCONTEXT_H */
diff --git a/arch/sh/include/cpu-common/cpu/timer.h b/arch/sh/include/cpu-common/cpu/timer.h
new file mode 100644
index 000000000..af5143875
--- /dev/null
+++ b/arch/sh/include/cpu-common/cpu/timer.h
@@ -0,0 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_CPU_SH2_TIMER_H
+#define __ASM_CPU_SH2_TIMER_H
+
+/* Nothing needed yet */
+
+#endif /* __ASM_CPU_SH2_TIMER_H */