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Yunseong Kim e9b33376bd ksmbd: validate ipc response length before dereferencing its fields
ipc_validate_msg() computes the expected message size by reading length
fields out of the response buffer supplied by the userspace ksmbd daemon
(payload_sz, session_key_len, ngroups, ...).  Those fields are read before
the buffer is verified to be large enough to contain the struct they belong
to, so a short response makes the read land past the end of the allocation.

handle_response() sizes entry->response purely from the netlink attribute
length (nla_len()) and only guards the leading handle read, so the daemon
can install a response as small as the kmalloc-8 object seen below.  When
ipc_msg_send_request() then calls ipc_validate_msg() for a
KSMBD_EVENT_RPC_REQUEST, the cast to struct ksmbd_rpc_command reads
resp->payload_sz at offset 8 of an 8-byte allocation:

[ 3697.841381] ==================================================================
[ 3697.844099] BUG: KASAN: slab-out-of-bounds in ipc_msg_send_request+0x763/0x800
[ 3697.846604] Read of size 4 at addr ffff888105f95910 by task kworker/4:3/20682
[ 3697.849061]
[ 3697.849801] CPU: 4 UID: 0 PID: 20682 Comm: kworker/4:3 Not tainted 7.2.0-rc3-next-20260717-virtme #117 PREEMPT(lazy)
[ 3697.850077] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014
[ 3697.850303] Workqueue: ksmbd-io handle_ksmbd_work
[ 3697.850592] Call Trace:
[ 3697.850794]  <TASK>
[ 3697.850952]  __dump_stack+0x21/0x60
[ 3697.851239]  dump_stack_lvl+0xc2/0x100
[ 3697.851528]  print_address_description+0x77/0x200
[ 3697.851816]  ? ipc_msg_send_request+0x763/0x800
[ 3697.852024]  print_report+0x58/0x70
[ 3697.852316]  kasan_report+0x117/0x150
[ 3697.852585]  ? down_write+0x146/0x1f0
[ 3697.852809]  ? ipc_msg_send_request+0x763/0x800
[ 3697.853082]  ipc_msg_send_request+0x763/0x800
[ 3697.853385]  ? __pfx_ipc_msg_send_request+0x10/0x10
[ 3697.853604]  ? kasan_unpoison+0x48/0x70
[ 3697.853936]  ? __pfx___up_read+0x10/0x10
[ 3697.854221]  ksmbd_rpc_ioctl+0x380/0x520
[ 3697.854542]  ? __pfx_ksmbd_rpc_ioctl+0x10/0x10
[ 3697.854757]  ? kasan_unpoison+0x48/0x70
[ 3697.854962]  ? copy_from_kernel_nofault+0x32c/0x4e0
[ 3697.855166]  ? kasan_unpoison+0x48/0x70
[ 3697.855416]  fsctl_pipe_transceive+0x139/0x7a0
[ 3697.855705]  ? __pfx_copy_from_kernel_nofault+0x10/0x10
[ 3697.855937]  ? __pfx_fsctl_pipe_transceive+0x10/0x10
[ 3697.856388]  ? __sanitizer_cov_trace_switch+0x7b/0x140
[ 3697.856620]  smb2_ioctl+0x1141/0x3420
[ 3697.856994]  ? __pfx_smb2_ioctl+0x10/0x10
[ 3697.857182]  ? get_smb2_cmd_val+0xe3/0x1c0
[ 3697.857655]  handle_ksmbd_work+0x9ad/0x15e0
[ 3697.858034]  ? __pfx_handle_ksmbd_work+0x10/0x10
[ 3697.858251]  ? lock_release+0xf7/0x360
[ 3697.858466]  ? process_scheduled_works+0x954/0x1600
[ 3697.858698]  ? process_scheduled_works+0x954/0x1600
[ 3697.858905]  process_scheduled_works+0xc22/0x1600
[ 3697.859368]  ? __pfx_process_scheduled_works+0x10/0x10
[ 3697.859637]  ? __pfx_assign_work+0x10/0x10
[ 3697.859896]  ? lock_is_held_type+0x7b/0x110
[ 3697.860146]  worker_thread+0x975/0xee0
[ 3697.860524]  ? __pfx_do_raw_spin_lock+0x10/0x10
[ 3697.860830]  ? __kthread_parkme+0x21e/0x260
[ 3697.861105]  kthread+0x3a6/0x490
[ 3697.861423]  ? __pfx_worker_thread+0x10/0x10
[ 3697.861643]  ? __pfx_kthread+0x10/0x10
[ 3697.861878]  ret_from_fork+0x55a/0xa20
[ 3697.862194]  ? __pfx_ret_from_fork+0x10/0x10
[ 3697.862480]  ? __pfx_kthread+0x10/0x10
[ 3697.862714]  ret_from_fork_asm+0x1a/0x30
[ 3697.862965]  </TASK>
[ 3697.863039]
[ 3697.938882] Allocated by task 20761:
[ 3697.940257]  kasan_save_track+0x3e/0x80
[ 3697.941782]  __kasan_kmalloc+0x72/0x90
[ 3697.943228]  __kvmalloc_node_noprof+0x3e9/0x6a0
[ 3697.944948]  handle_generic_event+0x59b/0x750
[ 3697.946592]  genl_family_rcv_msg_doit+0x3d6/0x560
[ 3697.946977]  genl_rcv_msg+0x67c/0x900
[ 3697.947224]  netlink_rcv_skb+0x286/0x580
[ 3697.947488]  genl_rcv+0x2d/0x80
[ 3697.947706]  netlink_unicast+0x937/0xb70
[ 3697.947993]  netlink_sendmsg+0x977/0xc10
[ 3697.948268]  __sock_sendmsg+0x264/0x2d0
[ 3697.948536]  __sys_sendto+0x4de/0x690
[ 3697.948789]  __x64_sys_sendto+0x173/0x380
[ 3697.949069]  do_syscall_64+0x13d/0x420
[ 3697.949328]  entry_SYSCALL_64_after_hwframe+0x77/0x7f
[ 3697.949662]
[ 3697.949779] The buggy address belongs to the object at ffff888105f95908
[ 3697.949779]  which belongs to the cache kmalloc-8 of size 8
[ 3697.950550] The buggy address is located 0 bytes to the right of
[ 3697.950550]  allocated 8-byte region [ffff888105f95908, ffff888105f95910)
[ 3697.951455]
[ 3697.951574] The buggy address belongs to the physical page:
[ 3697.951958] page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888105f951b8 pfn:0x105f95
[ 3697.952571] flags: 0x100000000000200(workingset|node=0|zone=2)
[ 3697.952973] page_type: f5(slab)
[ 3697.953198] raw: 0100000000000200 ffff888100042640 ffffea0004063610 ffff888100040588
[ 3697.953707] raw: ffff888105f951b8 00000000001c000e 00000000f5000000 0000000000000000
[ 3697.954240] page dumped because: kasan: bad access detected
[ 3697.954616]
[ 3697.954734] Memory state around the buggy address:
[ 3697.955063]  ffff888105f95800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fa
[ 3697.955534]  ffff888105f95880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 3697.956006] >ffff888105f95900: fc 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 3697.956477]                          ^
[ 3697.956728]  ffff888105f95980: fc fc fc fa fc fc fc fc fc fc fc fc fc fc fc fc
[ 3697.957202]  ffff888105f95a00: fc fc fc fc fc fa fc fc fc fc fc fc fc fc fc fc
[ 3697.957671] ==================================================================

The final "entry->msg_sz != msg_sz" comparison cannot help: the offending
read has already happened by the time it runs.  Every case in the switch
shares this pattern.

Floor entry->msg_sz against the base struct of each event type before
dereferencing any of its length fields.  On failure ipc_msg_send_request()
already frees the response and returns NULL, so callers stay safe.

The malformed message originates from the ksmbd.mountd daemon over genl
netlink rather than a remote SMB client, so triggering it requires a buggy
or compromised daemon; it is still an out-of-bounds read the validator is
meant to prevent.

Fixes: d6a6aa81ea ("ksmbd: validate response sizes in ipc_validate_msg()")
Signed-off-by: Yunseong Kim <yunseong.kim@est.tech>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
2026-08-17 15:00:52 +09:00
arch - Add a proper kernel cmdline option to control the TLB invalidation method on 2026-08-16 10:28:31 -07:00
block block: stop the timeout timer when releasing a never added disk 2026-07-29 05:23:20 -06:00
certs treewide: fix indentation and whitespace in Kconfig files 2026-05-28 21:24:42 -07:00
crypto This push contains the following changes: 2026-08-10 08:36:22 -07:00
Documentation - Add a proper kernel cmdline option to control the TLB invalidation method on 2026-08-16 10:28:31 -07:00
drivers - Detect a broken EL2 virtual timer in the bcm2712 SoC boards (RPi5) and 2026-08-16 11:12:13 -07:00
fs ksmbd: validate ipc response length before dereferencing its fields 2026-08-17 15:00:52 +09:00
include - Detect a broken EL2 virtual timer in the bcm2712 SoC boards (RPi5) and 2026-08-16 11:12:13 -07:00
init rust: allow suspicious_runtime_symbol_definitions lint for Rust >= 1.98 2026-06-29 13:02:15 +02:00
io_uring io_uring/rsrc: reject overflowing regvec bvec byte counts 2026-08-12 19:53:35 -06:00
ipc kernel-7.2-rc1.misc 2026-06-15 03:05:50 +05:30
kernel - Make sure a delayed sched entity's runtime stats are updated at the right 2026-08-16 11:15:23 -07:00
lib This push contains the following changes: 2026-08-10 08:36:22 -07:00
LICENSES LICENSES: Add modern form of the LGPL-2.1 tags to the usage guide section 2025-10-22 07:58:19 +02:00
mm 17 hotfixes. 15 are cc:stable. 16 are for MM. 2026-08-06 20:29:38 -07:00
net A handful of tiny fixes, with the main ones being a follow-up for 2026-08-14 10:18:06 -07:00
rust Driver core fixes for 7.2-rc7 2026-08-08 07:13:29 -07:00
samples samples/damon/mtier: error out for zero quota goal target values 2026-08-04 20:02:02 -07:00
scripts kbuild: rpm-pkg: Preserve BTF sections in kernel modules during debuginfo stripping 2026-07-29 16:21:42 -07:00
security selinux/stable-7.2 PR 20260805 2026-08-05 13:40:11 -07:00
sound ASoC: Fixes for v7.2 2026-08-13 15:32:36 +02:00
tools vfs-7.2-rc8.fixes 2026-08-14 07:58:01 -07:00
usr kbuild: uapi: also test UAPI headers against C++ compilers 2026-03-25 13:24:42 +01:00
virt KVM/arm64 fixes for 7.2, take #2 2026-07-15 12:13:30 +02:00
.clang-format clang-format: fix formatting of guard() and scoped_guard() statements 2026-05-28 21:24:41 -07:00
.clippy.toml rust: bump Clippy's MSRV and clean incompatible_msrv allows 2026-04-07 09:51:39 +02:00
.cocciconfig
.editorconfig editorconfig: add rst extension 2026-01-26 19:07:09 -08:00
.get_maintainer.ignore .get_maintainer.ignore: add myself 2026-04-02 16:48:25 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore SPDX patches for 7.2-rc1 2026-06-22 12:06:22 -07:00
.mailmap There is a known WiFi/mt76 regression, waiting for a complete fix that 2026-08-13 08:37:26 -07:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS CREDITS: Add Wolfram Sang 2026-07-14 16:34:04 +02:00
Kbuild checksyscalls: move instance functionality into generic code 2026-04-05 09:21:32 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS Char / Misc and documentation fixes for 7.2-rc7 2026-08-08 16:25:59 -07:00
Makefile Linux 7.2 2026-08-16 14:32:26 -07:00
README docs: add AI Coding Assistants documentation 2026-01-06 14:55:06 -07:00

Linux kernel
============

The Linux kernel is the core of any Linux operating system. It manages hardware,
system resources, and provides the fundamental services for all other software.

Quick Start
-----------

* Report a bug: See Documentation/admin-guide/reporting-issues.rst
* Get the latest kernel: https://kernel.org
* Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst
* Join the community: https://lore.kernel.org/

Essential Documentation
-----------------------

All users should be familiar with:

* Building requirements: Documentation/process/changes.rst
* Code of Conduct: Documentation/process/code-of-conduct.rst
* License: See COPYING

Documentation can be built with make htmldocs or viewed online at:
https://www.kernel.org/doc/html/latest/


Who Are You?
============

Find your role below:

* New Kernel Developer - Getting started with kernel development
* Academic Researcher - Studying kernel internals and architecture
* Security Expert - Hardening and vulnerability analysis
* Backport/Maintenance Engineer - Maintaining stable kernels
* System Administrator - Configuring and troubleshooting
* Maintainer - Leading subsystems and reviewing patches
* Hardware Vendor - Writing drivers for new hardware
* Distribution Maintainer - Packaging kernels for distros
* AI Coding Assistant - LLMs and AI-powered development tools


For Specific Users
==================

New Kernel Developer
--------------------

Welcome! Start your kernel development journey here:

* Getting Started: Documentation/process/development-process.rst
* Your First Patch: Documentation/process/submitting-patches.rst
* Coding Style: Documentation/process/coding-style.rst
* Build System: Documentation/kbuild/index.rst
* Development Tools: Documentation/dev-tools/index.rst
* Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst
* Core APIs: Documentation/core-api/index.rst

Academic Researcher
-------------------

Explore the kernel's architecture and internals:

* Researcher Guidelines: Documentation/process/researcher-guidelines.rst
* Memory Management: Documentation/mm/index.rst
* Scheduler: Documentation/scheduler/index.rst
* Networking Stack: Documentation/networking/index.rst
* Filesystems: Documentation/filesystems/index.rst
* RCU (Read-Copy Update): Documentation/RCU/index.rst
* Locking Primitives: Documentation/locking/index.rst
* Power Management: Documentation/power/index.rst

Security Expert
---------------

Security documentation and hardening guides:

* Security Documentation: Documentation/security/index.rst
* LSM Development: Documentation/security/lsm-development.rst
* Self Protection: Documentation/security/self-protection.rst
* Reporting Vulnerabilities: Documentation/process/security-bugs.rst
* CVE Procedures: Documentation/process/cve.rst
* Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst
* Security Features: Documentation/userspace-api/seccomp_filter.rst

Backport/Maintenance Engineer
-----------------------------

Maintain and stabilize kernel versions:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* Backporting Guide: Documentation/process/backporting.rst
* Applying Patches: Documentation/process/applying-patches.rst
* Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git for Maintainers: Documentation/maintainer/configure-git.rst

System Administrator
--------------------

Configure, tune, and troubleshoot Linux systems:

* Admin Guide: Documentation/admin-guide/index.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst
* Tracing/Debugging: Documentation/trace/index.rst
* Performance Security: Documentation/admin-guide/perf-security.rst
* Hardware Monitoring: Documentation/hwmon/index.rst

Maintainer
----------

Lead kernel subsystems and manage contributions:

* Maintainer Handbook: Documentation/maintainer/index.rst
* Pull Requests: Documentation/maintainer/pull-requests.rst
* Managing Patches: Documentation/maintainer/modifying-patches.rst
* Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst
* Development Process: Documentation/process/maintainer-handbooks.rst
* Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git Configuration: Documentation/maintainer/configure-git.rst

Hardware Vendor
---------------

Write drivers and support new hardware:

* Driver API Guide: Documentation/driver-api/index.rst
* Driver Model: Documentation/driver-api/driver-model/driver.rst
* Device Drivers: Documentation/driver-api/infrastructure.rst
* Bus Types: Documentation/driver-api/driver-model/bus.rst
* Device Tree Bindings: Documentation/devicetree/bindings/
* Power Management: Documentation/driver-api/pm/index.rst
* DMA API: Documentation/core-api/dma-api.rst

Distribution Maintainer
-----------------------

Package and distribute the kernel:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* ABI Documentation: Documentation/ABI/README
* Kernel Configuration: Documentation/kbuild/kconfig.rst
* Module Signing: Documentation/admin-guide/module-signing.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst

AI Coding Assistant
-------------------

CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and
follow the AI coding assistants documentation before contributing to the Linux
kernel:

* Documentation/process/coding-assistants.rst

This documentation contains essential requirements about licensing, attribution,
and the Developer Certificate of Origin that all AI tools must comply with.


Communication and Support
=========================

* Mailing Lists: https://lore.kernel.org/
* IRC: #kernelnewbies on irc.oftc.net
* Bugzilla: https://bugzilla.kernel.org/
* MAINTAINERS file: Lists subsystem maintainers and mailing lists
* Email Clients: Documentation/process/email-clients.rst