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, 56 insertions, 0 deletions

diff --git a/drivers/crypto/qce/aead.h b/drivers/crypto/qce/aead.h
new file mode 100644
index 000000000..efb8477cc
--- /dev/null
+++ b/drivers/crypto/qce/aead.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2021, Linaro Limited. All rights reserved.
+ */
+
+#ifndef _AEAD_H_
+#define _AEAD_H_
+
+#include "common.h"
+#include "core.h"
+
+#define QCE_MAX_KEY_SIZE		64
+#define QCE_CCM4309_SALT_SIZE		3
+
+struct qce_aead_ctx {
+	u8 enc_key[QCE_MAX_KEY_SIZE];
+	u8 auth_key[QCE_MAX_KEY_SIZE];
+	u8 ccm4309_salt[QCE_CCM4309_SALT_SIZE];
+	unsigned int enc_keylen;
+	unsigned int auth_keylen;
+	unsigned int authsize;
+	bool need_fallback;
+	struct crypto_aead *fallback;
+};
+
+struct qce_aead_reqctx {
+	unsigned long flags;
+	u8 *iv;
+	unsigned int ivsize;
+	int src_nents;
+	int dst_nents;
+	struct scatterlist result_sg;
+	struct scatterlist adata_sg;
+	struct sg_table dst_tbl;
+	struct sg_table src_tbl;
+	struct scatterlist *dst_sg;
+	struct scatterlist *src_sg;
+	unsigned int cryptlen;
+	unsigned int assoclen;
+	unsigned char *adata;
+	u8 ccm_nonce[QCE_MAX_NONCE];
+	u8 ccmresult_buf[QCE_BAM_BURST_SIZE];
+	u8 ccm_rfc4309_iv[QCE_MAX_IV_SIZE];
+	struct aead_request fallback_req;
+};
+
+static inline struct qce_alg_template *to_aead_tmpl(struct crypto_aead *tfm)
+{
+	struct aead_alg *alg = crypto_aead_alg(tfm);
+
+	return container_of(alg, struct qce_alg_template, alg.aead);
+}
+
+extern const struct qce_algo_ops aead_ops;
+
+#endif /* _AEAD_H_ */