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, 336 insertions, 0 deletions

diff --git a/Documentation/driver-api/scsi.rst b/Documentation/driver-api/scsi.rst
new file mode 100644
index 000000000..8bbdfb018
--- /dev/null
+++ b/Documentation/driver-api/scsi.rst
@@ -0,0 +1,336 @@
+=====================
+SCSI Interfaces Guide
+=====================
+
+:Author: James Bottomley
+:Author: Rob Landley
+
+Introduction
+============
+
+Protocol vs bus
+---------------
+
+Once upon a time, the Small Computer Systems Interface defined both a
+parallel I/O bus and a data protocol to connect a wide variety of
+peripherals (disk drives, tape drives, modems, printers, scanners,
+optical drives, test equipment, and medical devices) to a host computer.
+
+Although the old parallel (fast/wide/ultra) SCSI bus has largely fallen
+out of use, the SCSI command set is more widely used than ever to
+communicate with devices over a number of different buses.
+
+The `SCSI protocol <https://www.t10.org/scsi-3.htm>`__ is a big-endian
+peer-to-peer packet based protocol. SCSI commands are 6, 10, 12, or 16
+bytes long, often followed by an associated data payload.
+
+SCSI commands can be transported over just about any kind of bus, and
+are the default protocol for storage devices attached to USB, SATA, SAS,
+Fibre Channel, FireWire, and ATAPI devices. SCSI packets are also
+commonly exchanged over Infiniband,
+TCP/IP (`iSCSI <https://en.wikipedia.org/wiki/ISCSI>`__), even `Parallel
+ports <http://cyberelk.net/tim/parport/parscsi.html>`__.
+
+Design of the Linux SCSI subsystem
+----------------------------------
+
+The SCSI subsystem uses a three layer design, with upper, mid, and low
+layers. Every operation involving the SCSI subsystem (such as reading a
+sector from a disk) uses one driver at each of the 3 levels: one upper
+layer driver, one lower layer driver, and the SCSI midlayer.
+
+The SCSI upper layer provides the interface between userspace and the
+kernel, in the form of block and char device nodes for I/O and ioctl().
+The SCSI lower layer contains drivers for specific hardware devices.
+
+In between is the SCSI mid-layer, analogous to a network routing layer
+such as the IPv4 stack. The SCSI mid-layer routes a packet based data
+protocol between the upper layer's /dev nodes and the corresponding
+devices in the lower layer. It manages command queues, provides error
+handling and power management functions, and responds to ioctl()
+requests.
+
+SCSI upper layer
+================
+
+The upper layer supports the user-kernel interface by providing device
+nodes.
+
+sd (SCSI Disk)
+--------------
+
+sd (sd_mod.o)
+
+sr (SCSI CD-ROM)
+----------------
+
+sr (sr_mod.o)
+
+st (SCSI Tape)
+--------------
+
+st (st.o)
+
+sg (SCSI Generic)
+-----------------
+
+sg (sg.o)
+
+ch (SCSI Media Changer)
+-----------------------
+
+ch (ch.c)
+
+SCSI mid layer
+==============
+
+SCSI midlayer implementation
+----------------------------
+
+include/scsi/scsi_device.h
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: include/scsi/scsi_device.h
+   :internal:
+
+drivers/scsi/scsi.c
+~~~~~~~~~~~~~~~~~~~
+
+Main file for the SCSI midlayer.
+
+.. kernel-doc:: drivers/scsi/scsi.c
+   :export:
+
+drivers/scsi/scsicam.c
+~~~~~~~~~~~~~~~~~~~~~~
+
+`SCSI Common Access
+Method <http://www.t10.org/ftp/t10/drafts/cam/cam-r12b.pdf>`__ support
+functions, for use with HDIO_GETGEO, etc.
+
+.. kernel-doc:: drivers/scsi/scsicam.c
+   :export:
+
+drivers/scsi/scsi_error.c
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Common SCSI error/timeout handling routines.
+
+.. kernel-doc:: drivers/scsi/scsi_error.c
+   :export:
+
+drivers/scsi/scsi_devinfo.c
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Manage scsi_dev_info_list, which tracks blacklisted and whitelisted
+devices.
+
+.. kernel-doc:: drivers/scsi/scsi_devinfo.c
+   :export:
+
+drivers/scsi/scsi_ioctl.c
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Handle ioctl() calls for SCSI devices.
+
+.. kernel-doc:: drivers/scsi/scsi_ioctl.c
+   :export:
+
+drivers/scsi/scsi_lib.c
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+SCSI queuing library.
+
+.. kernel-doc:: drivers/scsi/scsi_lib.c
+   :export:
+
+drivers/scsi/scsi_lib_dma.c
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+SCSI library functions depending on DMA (map and unmap scatter-gather
+lists).
+
+.. kernel-doc:: drivers/scsi/scsi_lib_dma.c
+   :export:
+
+drivers/scsi/scsi_proc.c
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The functions in this file provide an interface between the PROC file
+system and the SCSI device drivers It is mainly used for debugging,
+statistics and to pass information directly to the lowlevel driver. I.E.
+plumbing to manage /proc/scsi/\*
+
+.. kernel-doc:: drivers/scsi/scsi_proc.c
+
+drivers/scsi/scsi_netlink.c
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Infrastructure to provide async events from transports to userspace via
+netlink, using a single NETLINK_SCSITRANSPORT protocol for all
+transports. See `the original patch submission
+<https://lore.kernel.org/linux-scsi/1155070439.6275.5.camel@localhost.localdomain/>`__
+for more details.
+
+.. kernel-doc:: drivers/scsi/scsi_netlink.c
+   :internal:
+
+drivers/scsi/scsi_scan.c
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Scan a host to determine which (if any) devices are attached. The
+general scanning/probing algorithm is as follows, exceptions are made to
+it depending on device specific flags, compilation options, and global
+variable (boot or module load time) settings. A specific LUN is scanned
+via an INQUIRY command; if the LUN has a device attached, a scsi_device
+is allocated and setup for it. For every id of every channel on the
+given host, start by scanning LUN 0. Skip hosts that don't respond at
+all to a scan of LUN 0. Otherwise, if LUN 0 has a device attached,
+allocate and setup a scsi_device for it. If target is SCSI-3 or up,
+issue a REPORT LUN, and scan all of the LUNs returned by the REPORT LUN;
+else, sequentially scan LUNs up until some maximum is reached, or a LUN
+is seen that cannot have a device attached to it.
+
+.. kernel-doc:: drivers/scsi/scsi_scan.c
+   :export:
+
+drivers/scsi/scsi_sysctl.c
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Set up the sysctl entry: "/dev/scsi/logging_level"
+(DEV_SCSI_LOGGING_LEVEL) which sets/returns scsi_logging_level.
+
+drivers/scsi/scsi_sysfs.c
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+SCSI sysfs interface routines.
+
+.. kernel-doc:: drivers/scsi/scsi_sysfs.c
+   :export:
+
+drivers/scsi/hosts.c
+~~~~~~~~~~~~~~~~~~~~
+
+mid to lowlevel SCSI driver interface
+
+.. kernel-doc:: drivers/scsi/hosts.c
+   :export:
+
+drivers/scsi/scsi_common.c
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+general support functions
+
+.. kernel-doc:: drivers/scsi/scsi_common.c
+   :export:
+
+Transport classes
+-----------------
+
+Transport classes are service libraries for drivers in the SCSI lower
+layer, which expose transport attributes in sysfs.
+
+Fibre Channel transport
+~~~~~~~~~~~~~~~~~~~~~~~
+
+The file drivers/scsi/scsi_transport_fc.c defines transport attributes
+for Fibre Channel.
+
+.. kernel-doc:: drivers/scsi/scsi_transport_fc.c
+   :export:
+
+iSCSI transport class
+~~~~~~~~~~~~~~~~~~~~~
+
+The file drivers/scsi/scsi_transport_iscsi.c defines transport
+attributes for the iSCSI class, which sends SCSI packets over TCP/IP
+connections.
+
+.. kernel-doc:: drivers/scsi/scsi_transport_iscsi.c
+   :export:
+
+Serial Attached SCSI (SAS) transport class
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The file drivers/scsi/scsi_transport_sas.c defines transport
+attributes for Serial Attached SCSI, a variant of SATA aimed at large
+high-end systems.
+
+The SAS transport class contains common code to deal with SAS HBAs, an
+approximated representation of SAS topologies in the driver model, and
+various sysfs attributes to expose these topologies and management
+interfaces to userspace.
+
+In addition to the basic SCSI core objects this transport class
+introduces two additional intermediate objects: The SAS PHY as
+represented by struct sas_phy defines an "outgoing" PHY on a SAS HBA or
+Expander, and the SAS remote PHY represented by struct sas_rphy defines
+an "incoming" PHY on a SAS Expander or end device. Note that this is
+purely a software concept, the underlying hardware for a PHY and a
+remote PHY is the exactly the same.
+
+There is no concept of a SAS port in this code, users can see what PHYs
+form a wide port based on the port_identifier attribute, which is the
+same for all PHYs in a port.
+
+.. kernel-doc:: drivers/scsi/scsi_transport_sas.c
+   :export:
+
+SATA transport class
+~~~~~~~~~~~~~~~~~~~~
+
+The SATA transport is handled by libata, which has its own book of
+documentation in this directory.
+
+Parallel SCSI (SPI) transport class
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The file drivers/scsi/scsi_transport_spi.c defines transport
+attributes for traditional (fast/wide/ultra) SCSI buses.
+
+.. kernel-doc:: drivers/scsi/scsi_transport_spi.c
+   :export:
+
+SCSI RDMA (SRP) transport class
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The file drivers/scsi/scsi_transport_srp.c defines transport
+attributes for SCSI over Remote Direct Memory Access.
+
+.. kernel-doc:: drivers/scsi/scsi_transport_srp.c
+   :export:
+
+SCSI lower layer
+================
+
+Host Bus Adapter transport types
+--------------------------------
+
+Many modern device controllers use the SCSI command set as a protocol to
+communicate with their devices through many different types of physical
+connections.
+
+In SCSI language a bus capable of carrying SCSI commands is called a
+"transport", and a controller connecting to such a bus is called a "host
+bus adapter" (HBA).
+
+Debug transport
+~~~~~~~~~~~~~~~
+
+The file drivers/scsi/scsi_debug.c simulates a host adapter with a
+variable number of disks (or disk like devices) attached, sharing a
+common amount of RAM. Does a lot of checking to make sure that we are
+not getting blocks mixed up, and panics the kernel if anything out of
+the ordinary is seen.
+
+To be more realistic, the simulated devices have the transport
+attributes of SAS disks.
+
+For documentation see http://sg.danny.cz/sg/scsi_debug.html
+
+todo
+~~~~
+
+Parallel (fast/wide/ultra) SCSI, USB, SATA, SAS, Fibre Channel,
+FireWire, ATAPI devices, Infiniband, Parallel ports,
+netlink...