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, 74 insertions, 0 deletions

diff --git a/fs/smb/server/auth.h b/fs/smb/server/auth.h
new file mode 100644
index 000000000..7ce9c42d5
--- /dev/null
+++ b/fs/smb/server/auth.h
@@ -0,0 +1,74 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ *   Copyright (C) 2018 Samsung Electronics Co., Ltd.
+ */
+
+#ifndef __AUTH_H__
+#define __AUTH_H__
+
+#include "ntlmssp.h"
+
+#ifdef CONFIG_SMB_SERVER_KERBEROS5
+#define AUTH_GSS_LENGTH		96
+#define AUTH_GSS_PADDING	0
+#else
+#define AUTH_GSS_LENGTH		74
+#define AUTH_GSS_PADDING	6
+#endif
+
+#define CIFS_HMAC_MD5_HASH_SIZE	(16)
+#define CIFS_NTHASH_SIZE	(16)
+
+/*
+ * Size of the ntlm client response
+ */
+#define CIFS_AUTH_RESP_SIZE		24
+#define CIFS_SMB1_SIGNATURE_SIZE	8
+#define CIFS_SMB1_SESSKEY_SIZE		16
+
+#define KSMBD_AUTH_NTLMSSP	0x0001
+#define KSMBD_AUTH_KRB5		0x0002
+#define KSMBD_AUTH_MSKRB5	0x0004
+#define KSMBD_AUTH_KRB5U2U	0x0008
+
+struct ksmbd_session;
+struct ksmbd_conn;
+struct ksmbd_work;
+struct kvec;
+
+int ksmbd_crypt_message(struct ksmbd_work *work, struct kvec *iov,
+			unsigned int nvec, int enc);
+int ksmbd_crypt_rdma(struct ksmbd_conn *conn, const u8 *key,
+		     void *buf, unsigned int buflen, const u8 *nonce,
+		     unsigned int nonce_len, u8 *tag, unsigned int tag_len,
+		     bool enc);
+void ksmbd_copy_gss_neg_header(void *buf);
+int ksmbd_auth_ntlmv2(struct ksmbd_conn *conn, struct ksmbd_session *sess,
+		      struct ntlmv2_resp *ntlmv2, int blen, char *domain_name,
+		      char *cryptkey, char *sess_key);
+int ksmbd_decode_ntlmssp_auth_blob(struct authenticate_message *authblob,
+				   int blob_len, struct ksmbd_conn *conn,
+				   struct ksmbd_session *sess, char *sess_key);
+int ksmbd_decode_ntlmssp_neg_blob(struct negotiate_message *negblob,
+				  int blob_len, struct ksmbd_conn *conn);
+unsigned int
+ksmbd_build_ntlmssp_challenge_blob(struct challenge_message *chgblob,
+				   struct ksmbd_conn *conn);
+int ksmbd_krb5_authenticate(struct ksmbd_session *sess, char *in_blob,
+			    int in_len, char *out_blob, int *out_len,
+			    char *sess_key);
+void ksmbd_sign_smb2_pdu(struct ksmbd_conn *conn, char *key, struct kvec *iov,
+			 int n_vec, char *sig);
+void ksmbd_sign_smb3_pdu(struct ksmbd_conn *conn, char *key, struct kvec *iov,
+			 int n_vec, char *sig);
+int ksmbd_gen_smb30_signingkey(struct ksmbd_session *sess,
+			       struct ksmbd_conn *conn);
+int ksmbd_gen_smb311_signingkey(struct ksmbd_session *sess,
+				struct ksmbd_conn *conn);
+void ksmbd_gen_smb30_encryptionkey(struct ksmbd_conn *conn,
+				   struct ksmbd_session *sess);
+void ksmbd_gen_smb311_encryptionkey(struct ksmbd_conn *conn,
+				    struct ksmbd_session *sess);
+int ksmbd_gen_preauth_integrity_hash(struct ksmbd_conn *conn, char *buf,
+				     __u8 *pi_hash);
+#endif