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, 343 insertions, 0 deletions

diff --git a/fs/smb/server/smb2ops.c b/fs/smb/server/smb2ops.c
new file mode 100644
index 000000000..4578291fb
--- /dev/null
+++ b/fs/smb/server/smb2ops.c
@@ -0,0 +1,343 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *   Copyright (C) 2016 Namjae Jeon <linkinjeon@kernel.org>
+ *   Copyright (C) 2018 Samsung Electronics Co., Ltd.
+ */
+
+#include <linux/slab.h>
+#include "glob.h"
+
+#include "auth.h"
+#include "connection.h"
+#include "smb_common.h"
+#include "server.h"
+#include "stats.h"
+
+static struct smb_version_values smb21_server_values = {
+	.version_string = SMB21_VERSION_STRING,
+	.protocol_id = SMB21_PROT_ID,
+	.req_capabilities = SMB2_GLOBAL_CAP_LARGE_MTU,
+	.max_read_size = SMB21_DEFAULT_IOSIZE,
+	.max_write_size = SMB21_DEFAULT_IOSIZE,
+	.max_trans_size = SMB21_DEFAULT_IOSIZE,
+	.max_credits = SMB2_MAX_CREDITS,
+	.large_lock_type = 0,
+	.exclusive_lock_type = SMB2_LOCKFLAG_EXCLUSIVE,
+	.shared_lock_type = SMB2_LOCKFLAG_SHARED,
+	.unlock_lock_type = SMB2_LOCKFLAG_UNLOCK,
+	.header_size = sizeof(struct smb2_hdr),
+	.max_header_size = MAX_SMB2_HDR_SIZE,
+	.read_rsp_size = sizeof(struct smb2_read_rsp),
+	.lock_cmd = SMB2_LOCK,
+	.cap_unix = 0,
+	.cap_nt_find = SMB2_NT_FIND,
+	.cap_large_files = SMB2_LARGE_FILES,
+	.create_lease_size = sizeof(struct create_lease),
+	.create_durable_size = sizeof(struct create_durable_rsp),
+	.create_mxac_size = sizeof(struct create_mxac_rsp),
+	.create_disk_id_size = sizeof(struct create_disk_id_rsp),
+	.create_posix_size = sizeof(struct create_posix_rsp),
+	.create_aapl_size = AAPL_RSP_MAX_SIZE,
+};
+
+static struct smb_version_values smb30_server_values = {
+	.version_string = SMB30_VERSION_STRING,
+	.protocol_id = SMB30_PROT_ID,
+	.req_capabilities = SMB2_GLOBAL_CAP_LARGE_MTU,
+	.max_read_size = SMB3_DEFAULT_IOSIZE,
+	.max_write_size = SMB3_DEFAULT_IOSIZE,
+	.max_trans_size = SMB3_DEFAULT_TRANS_SIZE,
+	.max_credits = SMB2_MAX_CREDITS,
+	.large_lock_type = 0,
+	.exclusive_lock_type = SMB2_LOCKFLAG_EXCLUSIVE,
+	.shared_lock_type = SMB2_LOCKFLAG_SHARED,
+	.unlock_lock_type = SMB2_LOCKFLAG_UNLOCK,
+	.header_size = sizeof(struct smb2_hdr),
+	.max_header_size = MAX_SMB2_HDR_SIZE,
+	.read_rsp_size = sizeof(struct smb2_read_rsp),
+	.lock_cmd = SMB2_LOCK,
+	.cap_unix = 0,
+	.cap_nt_find = SMB2_NT_FIND,
+	.cap_large_files = SMB2_LARGE_FILES,
+	.create_lease_size = sizeof(struct create_lease_v2),
+	.create_durable_size = sizeof(struct create_durable_rsp),
+	.create_durable_v2_size = sizeof(struct create_durable_rsp_v2),
+	.create_mxac_size = sizeof(struct create_mxac_rsp),
+	.create_disk_id_size = sizeof(struct create_disk_id_rsp),
+	.create_posix_size = sizeof(struct create_posix_rsp),
+	.create_aapl_size = AAPL_RSP_MAX_SIZE,
+};
+
+static struct smb_version_values smb302_server_values = {
+	.version_string = SMB302_VERSION_STRING,
+	.protocol_id = SMB302_PROT_ID,
+	.req_capabilities = SMB2_GLOBAL_CAP_LARGE_MTU,
+	.max_read_size = SMB3_DEFAULT_IOSIZE,
+	.max_write_size = SMB3_DEFAULT_IOSIZE,
+	.max_trans_size = SMB3_DEFAULT_TRANS_SIZE,
+	.max_credits = SMB2_MAX_CREDITS,
+	.large_lock_type = 0,
+	.exclusive_lock_type = SMB2_LOCKFLAG_EXCLUSIVE,
+	.shared_lock_type = SMB2_LOCKFLAG_SHARED,
+	.unlock_lock_type = SMB2_LOCKFLAG_UNLOCK,
+	.header_size = sizeof(struct smb2_hdr),
+	.max_header_size = MAX_SMB2_HDR_SIZE,
+	.read_rsp_size = sizeof(struct smb2_read_rsp),
+	.lock_cmd = SMB2_LOCK,
+	.cap_unix = 0,
+	.cap_nt_find = SMB2_NT_FIND,
+	.cap_large_files = SMB2_LARGE_FILES,
+	.create_lease_size = sizeof(struct create_lease_v2),
+	.create_durable_size = sizeof(struct create_durable_rsp),
+	.create_durable_v2_size = sizeof(struct create_durable_rsp_v2),
+	.create_mxac_size = sizeof(struct create_mxac_rsp),
+	.create_disk_id_size = sizeof(struct create_disk_id_rsp),
+	.create_posix_size = sizeof(struct create_posix_rsp),
+	.create_aapl_size = AAPL_RSP_MAX_SIZE,
+};
+
+static struct smb_version_values smb311_server_values = {
+	.version_string = SMB311_VERSION_STRING,
+	.protocol_id = SMB311_PROT_ID,
+	.req_capabilities = SMB2_GLOBAL_CAP_LARGE_MTU,
+	.max_read_size = SMB3_DEFAULT_IOSIZE,
+	.max_write_size = SMB3_DEFAULT_IOSIZE,
+	.max_trans_size = SMB3_DEFAULT_TRANS_SIZE,
+	.max_credits = SMB2_MAX_CREDITS,
+	.large_lock_type = 0,
+	.exclusive_lock_type = SMB2_LOCKFLAG_EXCLUSIVE,
+	.shared_lock_type = SMB2_LOCKFLAG_SHARED,
+	.unlock_lock_type = SMB2_LOCKFLAG_UNLOCK,
+	.header_size = sizeof(struct smb2_hdr),
+	.max_header_size = MAX_SMB2_HDR_SIZE,
+	.read_rsp_size = sizeof(struct smb2_read_rsp),
+	.lock_cmd = SMB2_LOCK,
+	.cap_unix = 0,
+	.cap_nt_find = SMB2_NT_FIND,
+	.cap_large_files = SMB2_LARGE_FILES,
+	.create_lease_size = sizeof(struct create_lease_v2),
+	.create_durable_size = sizeof(struct create_durable_rsp),
+	.create_durable_v2_size = sizeof(struct create_durable_rsp_v2),
+	.create_mxac_size = sizeof(struct create_mxac_rsp),
+	.create_disk_id_size = sizeof(struct create_disk_id_rsp),
+	.create_posix_size = sizeof(struct create_posix_rsp),
+	.create_aapl_size = AAPL_RSP_MAX_SIZE,
+};
+
+static struct smb_version_ops smb2_0_server_ops = {
+	.get_cmd_val		=	get_smb2_cmd_val,
+	.inc_reqs		=	ksmbd_counter_inc_reqs,
+	.init_rsp_hdr		=	init_smb2_rsp_hdr,
+	.set_rsp_status		=	set_smb2_rsp_status,
+	.allocate_rsp_buf       =       smb2_allocate_rsp_buf,
+	.set_rsp_credits	=	smb2_set_rsp_credits,
+	.check_user_session	=	smb2_check_user_session,
+	.get_ksmbd_tcon		=	smb2_get_ksmbd_tcon,
+	.is_sign_req		=	smb2_is_sign_req,
+	.check_sign_req		=	smb2_check_sign_req,
+	.set_sign_rsp		=	smb2_set_sign_rsp
+};
+
+static struct smb_version_ops smb3_0_server_ops = {
+	.get_cmd_val		=	get_smb2_cmd_val,
+	.inc_reqs		=	ksmbd_counter_inc_reqs,
+	.init_rsp_hdr		=	init_smb2_rsp_hdr,
+	.set_rsp_status		=	set_smb2_rsp_status,
+	.allocate_rsp_buf       =       smb2_allocate_rsp_buf,
+	.set_rsp_credits	=	smb2_set_rsp_credits,
+	.check_user_session	=	smb2_check_user_session,
+	.get_ksmbd_tcon		=	smb2_get_ksmbd_tcon,
+	.is_sign_req		=	smb2_is_sign_req,
+	.check_sign_req		=	smb3_check_sign_req,
+	.set_sign_rsp		=	smb3_set_sign_rsp,
+	.generate_signingkey	=	ksmbd_gen_smb30_signingkey,
+	.generate_encryptionkey	=	ksmbd_gen_smb30_encryptionkey,
+	.is_transform_hdr	=	smb3_is_transform_hdr,
+	.decrypt_req		=	smb3_decrypt_req,
+	.encrypt_resp		=	smb3_encrypt_resp
+};
+
+static struct smb_version_ops smb3_11_server_ops = {
+	.get_cmd_val		=	get_smb2_cmd_val,
+	.inc_reqs		=	ksmbd_counter_inc_reqs,
+	.init_rsp_hdr		=	init_smb2_rsp_hdr,
+	.set_rsp_status		=	set_smb2_rsp_status,
+	.allocate_rsp_buf       =       smb2_allocate_rsp_buf,
+	.set_rsp_credits	=	smb2_set_rsp_credits,
+	.check_user_session	=	smb2_check_user_session,
+	.get_ksmbd_tcon		=	smb2_get_ksmbd_tcon,
+	.is_sign_req		=	smb2_is_sign_req,
+	.check_sign_req		=	smb3_check_sign_req,
+	.set_sign_rsp		=	smb3_set_sign_rsp,
+	.generate_signingkey	=	ksmbd_gen_smb311_signingkey,
+	.generate_encryptionkey	=	ksmbd_gen_smb311_encryptionkey,
+	.is_transform_hdr	=	smb3_is_transform_hdr,
+	.decrypt_req		=	smb3_decrypt_req,
+	.encrypt_resp		=	smb3_encrypt_resp
+};
+
+static struct smb_version_cmds smb2_0_server_cmds[NUMBER_OF_SMB2_COMMANDS] = {
+	[SMB2_NEGOTIATE_HE]	=	{ .proc = smb2_negotiate_request, },
+	[SMB2_SESSION_SETUP_HE] =	{ .proc = smb2_sess_setup, },
+	[SMB2_TREE_CONNECT_HE]  =	{ .proc = smb2_tree_connect,},
+	[SMB2_TREE_DISCONNECT_HE]  =	{ .proc = smb2_tree_disconnect,},
+	[SMB2_LOGOFF_HE]	=	{ .proc = smb2_session_logoff,},
+	[SMB2_CREATE_HE]	=	{ .proc = smb2_open},
+	[SMB2_QUERY_INFO_HE]	=	{ .proc = smb2_query_info},
+	[SMB2_QUERY_DIRECTORY_HE] =	{ .proc = smb2_query_dir},
+	[SMB2_CLOSE_HE]		=	{ .proc = smb2_close},
+	[SMB2_ECHO_HE]		=	{ .proc = smb2_echo},
+	[SMB2_SET_INFO_HE]      =       { .proc = smb2_set_info},
+	[SMB2_READ_HE]		=	{ .proc = smb2_read},
+	[SMB2_WRITE_HE]		=	{ .proc = smb2_write},
+	[SMB2_FLUSH_HE]		=	{ .proc = smb2_flush},
+	[SMB2_CANCEL_HE]	=	{ .proc = smb2_cancel},
+	[SMB2_LOCK_HE]		=	{ .proc = smb2_lock},
+	[SMB2_IOCTL_HE]		=	{ .proc = smb2_ioctl},
+	[SMB2_OPLOCK_BREAK_HE]	=	{ .proc = smb2_oplock_break},
+	[SMB2_CHANGE_NOTIFY_HE]	=	{ .proc = smb2_notify},
+};
+
+/**
+ * init_smb2_1_server() - initialize a smb server connection with smb2.1
+ *			command dispatcher
+ * @conn:	connection instance
+ */
+void init_smb2_1_server(struct ksmbd_conn *conn)
+{
+	conn->vals = &smb21_server_values;
+	conn->ops = &smb2_0_server_ops;
+	conn->cmds = smb2_0_server_cmds;
+	conn->max_cmds = ARRAY_SIZE(smb2_0_server_cmds);
+	conn->signing_algorithm = SIGNING_ALG_HMAC_SHA256_LE;
+
+	if (server_conf.flags & KSMBD_GLOBAL_FLAG_SMB2_LEASES)
+		conn->vals->req_capabilities |= SMB2_GLOBAL_CAP_LEASING;
+}
+
+/**
+ * init_smb3_0_server() - initialize a smb server connection with smb3.0
+ *			command dispatcher
+ * @conn:	connection instance
+ */
+void init_smb3_0_server(struct ksmbd_conn *conn)
+{
+	conn->vals = &smb30_server_values;
+	conn->ops = &smb3_0_server_ops;
+	conn->cmds = smb2_0_server_cmds;
+	conn->max_cmds = ARRAY_SIZE(smb2_0_server_cmds);
+	conn->signing_algorithm = SIGNING_ALG_AES_CMAC_LE;
+
+	if (server_conf.flags & KSMBD_GLOBAL_FLAG_SMB2_LEASES)
+		conn->vals->req_capabilities |= SMB2_GLOBAL_CAP_LEASING |
+			SMB2_GLOBAL_CAP_DIRECTORY_LEASING;
+
+	if (server_conf.flags & KSMBD_GLOBAL_FLAG_SMB2_ENCRYPTION &&
+	    conn->cli_cap & SMB2_GLOBAL_CAP_ENCRYPTION)
+		conn->vals->req_capabilities |= SMB2_GLOBAL_CAP_ENCRYPTION;
+
+	if (server_conf.flags & KSMBD_GLOBAL_FLAG_SMB2_ENCRYPTION ||
+	    (!(server_conf.flags & KSMBD_GLOBAL_FLAG_SMB2_ENCRYPTION_OFF) &&
+	     conn->cli_cap & SMB2_GLOBAL_CAP_ENCRYPTION))
+		conn->vals->req_capabilities |= SMB2_GLOBAL_CAP_ENCRYPTION;
+
+	if (server_conf.flags & KSMBD_GLOBAL_FLAG_SMB3_MULTICHANNEL)
+		conn->vals->req_capabilities |= SMB2_GLOBAL_CAP_MULTI_CHANNEL;
+}
+
+/**
+ * init_smb3_02_server() - initialize a smb server connection with smb3.02
+ *			command dispatcher
+ * @conn:	connection instance
+ */
+void init_smb3_02_server(struct ksmbd_conn *conn)
+{
+	conn->vals = &smb302_server_values;
+	conn->ops = &smb3_0_server_ops;
+	conn->cmds = smb2_0_server_cmds;
+	conn->max_cmds = ARRAY_SIZE(smb2_0_server_cmds);
+	conn->signing_algorithm = SIGNING_ALG_AES_CMAC_LE;
+
+	if (server_conf.flags & KSMBD_GLOBAL_FLAG_SMB2_LEASES)
+		conn->vals->req_capabilities |= SMB2_GLOBAL_CAP_LEASING |
+			SMB2_GLOBAL_CAP_DIRECTORY_LEASING;
+
+	if (server_conf.flags & KSMBD_GLOBAL_FLAG_SMB2_ENCRYPTION ||
+	    (!(server_conf.flags & KSMBD_GLOBAL_FLAG_SMB2_ENCRYPTION_OFF) &&
+	     conn->cli_cap & SMB2_GLOBAL_CAP_ENCRYPTION))
+		conn->vals->req_capabilities |= SMB2_GLOBAL_CAP_ENCRYPTION;
+
+	if (server_conf.flags & KSMBD_GLOBAL_FLAG_SMB3_MULTICHANNEL)
+		conn->vals->req_capabilities |= SMB2_GLOBAL_CAP_MULTI_CHANNEL;
+
+	/*
+	 * Durable handles are in-memory only.  Do not advertise persistent
+	 * handles until CA recovery and fencing are implemented.
+	 */
+}
+
+/**
+ * init_smb3_11_server() - initialize a smb server connection with smb3.11
+ *			command dispatcher
+ * @conn:	connection instance
+ */
+int init_smb3_11_server(struct ksmbd_conn *conn)
+{
+	conn->vals = &smb311_server_values;
+	conn->ops = &smb3_11_server_ops;
+	conn->cmds = smb2_0_server_cmds;
+	conn->max_cmds = ARRAY_SIZE(smb2_0_server_cmds);
+	conn->signing_algorithm = SIGNING_ALG_AES_CMAC_LE;
+
+	if (server_conf.flags & KSMBD_GLOBAL_FLAG_SMB2_LEASES)
+		conn->vals->req_capabilities |= SMB2_GLOBAL_CAP_LEASING |
+			SMB2_GLOBAL_CAP_DIRECTORY_LEASING;
+
+	if (server_conf.flags & KSMBD_GLOBAL_FLAG_SMB3_MULTICHANNEL)
+		conn->vals->req_capabilities |= SMB2_GLOBAL_CAP_MULTI_CHANNEL;
+
+	/* See init_smb3_02_server(): persistent handles require CA recovery. */
+	return 0;
+}
+
+void init_smb2_max_read_size(unsigned int sz)
+{
+	sz = clamp_val(sz, SMB3_MIN_IOSIZE, SMB3_MAX_IOSIZE);
+	smb21_server_values.max_read_size = sz;
+	smb30_server_values.max_read_size = sz;
+	smb302_server_values.max_read_size = sz;
+	smb311_server_values.max_read_size = sz;
+}
+
+void init_smb2_max_write_size(unsigned int sz)
+{
+	sz = clamp_val(sz, SMB3_MIN_IOSIZE, SMB3_MAX_IOSIZE);
+	smb21_server_values.max_write_size = sz;
+	smb30_server_values.max_write_size = sz;
+	smb302_server_values.max_write_size = sz;
+	smb311_server_values.max_write_size = sz;
+}
+
+void init_smb2_max_trans_size(unsigned int sz)
+{
+	sz = clamp_val(sz, SMB3_MIN_IOSIZE, SMB3_MAX_IOSIZE);
+	smb21_server_values.max_trans_size = sz;
+	smb30_server_values.max_trans_size = sz;
+	smb302_server_values.max_trans_size = sz;
+	smb311_server_values.max_trans_size = sz;
+}
+
+void init_smb2_max_credits(unsigned int sz)
+{
+	/*
+	 * The command sequence window (and its backing bitmap) can track at
+	 * most SMB2_MAX_CREDITS outstanding sequence numbers, so the number of
+	 * credits granted on a connection must not exceed that.
+	 */
+	if (sz > SMB2_MAX_CREDITS)
+		sz = SMB2_MAX_CREDITS;
+	smb21_server_values.max_credits = sz;
+	smb30_server_values.max_credits = sz;
+	smb302_server_values.max_credits = sz;
+	smb311_server_values.max_credits = sz;
+}