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, 232 insertions, 0 deletions

diff --git a/fs/smb/client/Kconfig b/fs/smb/client/Kconfig
new file mode 100644
index 000000000..2b7db5fb0
--- /dev/null
+++ b/fs/smb/client/Kconfig
@@ -0,0 +1,232 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config CIFS
+	tristate "SMB3 and CIFS support (advanced network filesystem)"
+	depends on INET
+	select NLS
+	select NLS_UCS2_UTILS
+	select CRYPTO
+	select CRYPTO_AEAD2
+	select CRYPTO_CCM
+	select CRYPTO_GCM
+	select CRYPTO_AES
+	select CRYPTO_LIB_AES_CBC_MACS
+	select CRYPTO_LIB_ARC4
+	select CRYPTO_LIB_MD5
+	select CRYPTO_LIB_SHA256
+	select CRYPTO_LIB_SHA512
+	select KEYS
+	select DNS_RESOLVER
+	select ASN1
+	select OID_REGISTRY
+	select NETFS_SUPPORT
+	help
+	  This is the client VFS module for the SMB3 family of network file
+	  protocols (including the most recent, most secure dialect SMB3.1.1).
+	  This module also includes support for earlier dialects such as
+	  SMB2.1, SMB2 and even the old Common Internet File System (CIFS)
+	  protocol.  CIFS was the successor to the original network filesystem
+	  protocol, Server Message Block (SMB ie SMB1), the native file sharing
+	  mechanism for most early PC operating systems.
+
+	  The SMB3.1.1 protocol is supported by most modern operating systems
+	  and NAS appliances (e.g. Samba, Windows 11, Windows Server 2022,
+	  MacOS) and even in the cloud (e.g. Microsoft Azure) and also by the
+	  Linux kernel server, ksmbd.  Support for the older CIFS protocol was
+	  included in Windows NT4, 2000 and XP (and later). Use of dialects
+	  older than SMB2.1 is often discouraged on public networks.
+	  This module also provides limited support for OS/2 and Windows ME
+	  and similar very old servers.
+
+	  This module provides an advanced network file system client for
+	  mounting to SMB3 (and CIFS) compliant servers.  It includes support
+	  for DFS (hierarchical name space), secure per-user session
+	  establishment via Kerberos or NTLMv2, RDMA (smbdirect), advanced
+	  security features, per-share encryption, packet-signing, snapshots,
+	  directory leases, safe distributed caching (leases), multichannel,
+	  Unicode and other internationalization improvements.
+
+	  In general, the default dialects, SMB3 and later, enable better
+	  performance, security and features, than would be possible with CIFS.
+
+	  If you need to mount to Samba, Azure, ksmbd, Macs or Windows from this
+	  machine, say Y.
+
+config CIFS_STATS2
+	bool "Extended statistics"
+	depends on CIFS
+	default y
+	help
+	  Enabling this option will allow more detailed statistics on SMB
+	  request timing to be displayed in /proc/fs/cifs/DebugData and also
+	  allow optional logging of slow responses to dmesg (depending on the
+	  value of /proc/fs/cifs/cifsFYI). See Documentation/admin-guide/cifs/usage.rst
+	  for more details. These additional statistics may have a minor effect
+	  on performance and memory utilization.
+
+	  If unsure, say Y.
+
+config CIFS_ALLOW_INSECURE_LEGACY
+	bool "Support legacy servers which use less secure dialects"
+	depends on CIFS
+	default y
+	help
+	  Modern dialects, SMB2.1 and later (including SMB3 and 3.1.1), have
+	  additional security features, including protection against
+	  man-in-the-middle attacks and stronger crypto hashes, so the use
+	  of legacy dialects (SMB1/CIFS and SMB2.0) is discouraged.
+
+	  Disabling this option prevents users from using vers=1.0 or vers=2.0
+	  on mounts with cifs.ko
+
+	  If unsure, say Y.
+
+config CIFS_UPCALL
+	bool "Kerberos/SPNEGO advanced session setup"
+	depends on CIFS
+	help
+	  Enables an upcall mechanism for CIFS which accesses userspace helper
+	  utilities to provide SPNEGO packaged (RFC 4178) Kerberos tickets
+	  which are needed to mount to certain secure servers (for which more
+	  secure Kerberos authentication is required). If unsure, say Y.
+
+config CIFS_XATTR
+	bool "CIFS extended attributes"
+	depends on CIFS
+	help
+	  Extended attributes are name:value pairs associated with inodes by
+	  the kernel or by users (see the attr(5) manual page for details).
+	  CIFS maps the name of extended attributes beginning with the user
+	  namespace prefix to SMB/CIFS EAs.  EAs are stored on Windows
+	  servers without the user namespace prefix, but their names are
+	  seen by Linux cifs clients prefaced by the user namespace prefix.
+	  The system namespace (used by some filesystems to store ACLs) is
+	  not supported at this time.
+
+	  If unsure, say Y.
+
+config CIFS_POSIX
+	bool "CIFS POSIX Extensions"
+	depends on CIFS && CIFS_ALLOW_INSECURE_LEGACY && CIFS_XATTR
+	help
+	  Enabling this option will cause the cifs client to attempt to
+	  negotiate a feature of the older cifs dialect with servers, such as
+	  Samba 3.0.5 or later, that optionally can handle more POSIX like
+	  (rather than Windows like) file behavior.  It also enables support
+	  for POSIX ACLs (getfacl and setfacl) to servers (such as Samba 3.10
+	  and later) which can negotiate CIFS POSIX ACL support.  This config
+	  option is not needed when mounting with SMB3.1.1. If unsure, say N.
+
+config CIFS_DEBUG
+	bool "Enable CIFS debugging routines"
+	default y
+	depends on CIFS
+	help
+	  Enabling this option adds helpful debugging messages to
+	  the cifs code which increases the size of the cifs module.
+	  If unsure, say Y.
+
+config CIFS_DEBUG2
+	bool "Enable additional CIFS debugging routines"
+	depends on CIFS_DEBUG
+	help
+	  Enabling this option adds a few more debugging routines
+	  to the cifs code which slightly increases the size of
+	  the cifs module and can cause additional logging of debug
+	  messages in some error paths, slowing performance. This
+	  option can be turned off unless you are debugging
+	  cifs problems.  If unsure, say N.
+
+config CIFS_DEBUG_DUMP_KEYS
+	bool "Dump encryption keys for offline decryption (Unsafe)"
+	depends on CIFS_DEBUG
+	help
+	  Enabling this will dump the encryption and decryption keys
+	  used to communicate on an encrypted share connection on the
+	  console. This allows Wireshark to decrypt and dissect
+	  encrypted network captures. Enable this carefully.
+	  If unsure, say N.
+
+config CIFS_DFS_UPCALL
+	bool "DFS feature support"
+	depends on CIFS
+	help
+	  Distributed File System (DFS) support is used to access shares
+	  transparently in an enterprise name space, even if the share
+	  moves to a different server.  This feature also enables
+	  an upcall mechanism for CIFS which contacts userspace helper
+	  utilities to provide server name resolution (host names to
+	  IP addresses) which is needed in order to reconnect to
+	  servers if their addresses change or for implicit mounts of
+	  DFS junction points. If unsure, say Y.
+
+config CIFS_SWN_UPCALL
+	bool "SWN feature support"
+	depends on CIFS
+	help
+	  The Service Witness Protocol (SWN) is used to get notifications
+	  from a highly available server of resource state changes. This
+	  feature enables an upcall mechanism for CIFS which contacts a
+	  userspace daemon to establish the DCE/RPC connection to retrieve
+	  the cluster available interfaces and resource change notifications.
+	  If unsure, say Y.
+
+config CIFS_NFSD_EXPORT
+	bool "Allow nfsd to export CIFS file system"
+	depends on CIFS && BROKEN
+	help
+	  Allows NFS server to export a CIFS mounted share (nfsd over cifs)
+
+if CIFS
+
+config CIFS_SMB_DIRECT
+	bool "SMB Direct support"
+	depends on CIFS && INFINIBAND && INFINIBAND_ADDR_TRANS
+	depends on CIFS=m || INFINIBAND=y
+	select SMBDIRECT
+	help
+	  Enables SMB Direct support for SMB 3.0, 3.02 and 3.1.1.
+	  SMB Direct allows transferring SMB packets over RDMA. If unsure,
+	  say Y.
+
+config CIFS_FSCACHE
+	bool "Provide CIFS client caching support"
+	depends on CIFS=m && FSCACHE || CIFS=y && FSCACHE=y
+	help
+	  Makes CIFS FS-Cache capable. Say Y here if you want your CIFS data
+	  to be cached locally on disk through the general filesystem cache
+	  manager. If unsure, say N.
+
+config CIFS_ROOT
+	bool "SMB root file system (Experimental)"
+	depends on CIFS=y && IP_PNP
+	help
+	  Enables root file system support over SMB protocol.
+
+	  Most people say N here.
+
+config CIFS_COMPRESSION
+	bool "SMB message compression (Experimental)"
+	depends on CIFS
+	default n
+	help
+	  Enables over-the-wire message compression for SMB 3.1.1
+	  mounts when negotiated with the server.
+
+	  Only write requests with data size >= PAGE_SIZE will be
+	  compressed to avoid wasting resources.
+
+	  Say Y here if you want SMB traffic to be compressed.
+	  If unsure, say N.
+
+config SMB1_KUNIT_TESTS
+	tristate "KUnit tests for SMB1"
+	depends on SMB_KUNIT_TESTS && CIFS_ALLOW_INSECURE_LEGACY
+	default SMB_KUNIT_TESTS
+	help
+	  This builds the SMB1-specific KUnit tests.
+
+	  These tests are only enabled when legacy insecure SMB1 support
+	  (CIFS_ALLOW_INSECURE_LEGACY) is enabled.
+
+	  If unsure, say N.
+endif