From a5f7a5bb3b7f28ba7e4fa246775b29a0e5537255 Mon Sep 17 00:00:00 2001 From: Jinke Han Date: Tue, 8 Sep 2026 15:37:42 +0800 Subject: x86/kprobes: Fix crash when probing CS CALL instructions 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) Signed-off-by: Jinke Han Signed-off-by: Ingo Molnar Reviewed-by: Masami Hiramatsu (Google) Acked-by: Yafang Shao Acked-by: Borislav Petkov Cc: Peter Zijlstra Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000 --- drivers/crypto/geode-aes.h | 58 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) create mode 100644 drivers/crypto/geode-aes.h (limited to 'drivers/crypto/geode-aes.h') 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 -- cgit v1.3.1