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, 58 insertions, 0 deletions

diff --git a/drivers/crypto/geode-aes.h b/drivers/crypto/geode-aes.h
new file mode 100644
index 000000000..6d0a0cdc7
--- /dev/null
+++ b/drivers/crypto/geode-aes.h
@@ -0,0 +1,58 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* Copyright (C) 2003-2006, Advanced Micro Devices, Inc.
+ */
+
+#ifndef _GEODE_AES_H_
+#define _GEODE_AES_H_
+
+/* driver logic flags */
+#define AES_MODE_ECB 0
+#define AES_MODE_CBC 1
+
+#define AES_DIR_DECRYPT 0
+#define AES_DIR_ENCRYPT 1
+
+#define AES_FLAGS_HIDDENKEY (1 << 0)
+
+/* Register definitions */
+
+#define AES_CTRLA_REG  0x0000
+
+#define AES_CTRL_START     0x01
+#define AES_CTRL_DECRYPT   0x00
+#define AES_CTRL_ENCRYPT   0x02
+#define AES_CTRL_WRKEY     0x04
+#define AES_CTRL_DCA       0x08
+#define AES_CTRL_SCA       0x10
+#define AES_CTRL_CBC       0x20
+
+#define AES_INTR_REG  0x0008
+
+#define AES_INTRA_PENDING (1 << 16)
+#define AES_INTRB_PENDING (1 << 17)
+
+#define AES_INTR_PENDING  (AES_INTRA_PENDING | AES_INTRB_PENDING)
+#define AES_INTR_MASK     0x07
+
+#define AES_SOURCEA_REG   0x0010
+#define AES_DSTA_REG      0x0014
+#define AES_LENA_REG      0x0018
+#define AES_WRITEKEY0_REG 0x0030
+#define AES_WRITEIV0_REG  0x0040
+
+/*  A very large counter that is used to gracefully bail out of an
+ *  operation in case of trouble
+ */
+
+#define AES_OP_TIMEOUT    0x50000
+
+struct geode_aes_tfm_ctx {
+	u8 key[AES_KEYSIZE_128];
+	union {
+		struct crypto_skcipher *skcipher;
+		struct crypto_cipher *cip;
+	} fallback;
+	u32 keylen;
+};
+
+#endif