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Yunseong Kim 7405d0ba29 ksmbd: fix slab-out-of-bounds read in ksmbd_alloc_user()
ksmbd_alloc_user() copies resp->hash_sz bytes out of the mountd IPC
login response with

	user->passkey_sz = resp->hash_sz;
	user->passkey = kmalloc(resp->hash_sz, KSMBD_DEFAULT_GFP);
	if (user->passkey)
		memcpy(user->passkey, resp->hash, resp->hash_sz);

resp->hash_sz is a __u16 supplied by the response, but resp->hash[] is
only KSMBD_REQ_MAX_HASH_SZ bytes.  A malformed or malicious login
response can set hash_sz well beyond that (up to 65535), so the memcpy()
reads past the end of the response object.  ipc_validate_msg() does not
bound hash_sz, so reject any response whose hash_sz exceeds the on-stack
hash[] buffer before allocating and copying.

[ 2030.238706] BUG: KASAN: slab-out-of-bounds in ksmbd_alloc_user+0x278/0x680
[ 2030.240549] Read of size 65535 at addr ffff888121bb6680 by task kworker/4:1/18611
[ 2030.242296]
[ 2030.242710] CPU: 4 UID: 0 PID: 18611 Comm: kworker/4:1 Not tainted 7.1.0-next-20260623-virtme #96 PREEMPT(lazy)
[ 2030.242732] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014
[ 2030.242743] Workqueue: ksmbd-io handle_ksmbd_work
[ 2030.242763] Call Trace:
[ 2030.242769]  <TASK>
[ 2030.242776]  dump_stack_lvl+0xa2/0xd0
[ 2030.242794]  print_address_description+0x77/0x200
[ 2030.242815]  ? ksmbd_alloc_user+0x278/0x680
[ 2030.242831]  print_report+0x58/0x70
[ 2030.242848]  kasan_report+0x117/0x150
[ 2030.242869]  ? ksmbd_alloc_user+0x278/0x680
[ 2030.242888]  kasan_check_range+0x3c7/0x3f0
[ 2030.242908]  ? ksmbd_alloc_user+0x278/0x680
[ 2030.242925]  __asan_memcpy+0x29/0x70
[ 2030.242942]  ksmbd_alloc_user+0x278/0x680
[ 2030.242960]  ksmbd_login_user+0xc3/0x120
[ 2030.242978]  ntlm_authenticate+0x5e6/0x1b00
[ 2030.243017]  ? __pfx_ntlm_authenticate+0x10/0x10
[ 2030.243035]  ? ksmbd_session_lookup+0x188/0x1d0
[ 2030.243054]  ? __pfx_ksmbd_session_lookup+0x10/0x10
[ 2030.243090]  ? __sanitizer_cov_trace_switch+0x7b/0x140
[ 2030.243108]  smb2_sess_setup+0x1e4a/0x27b0
[ 2030.243126]  ? copy_from_kernel_nofault+0x199/0x300
[ 2030.243156]  ? __pfx_smb2_sess_setup+0x10/0x10
[ 2030.243173]  ? get_smb2_cmd_val+0xe3/0x1c0
[ 2030.243208]  handle_ksmbd_work+0x954/0x1280
[ 2030.243230]  ? __pfx_handle_ksmbd_work+0x10/0x10
[ 2030.243249]  ? process_scheduled_works+0xa07/0x1490
[ 2030.243270]  ? process_scheduled_works+0xa07/0x1490
[ 2030.243291]  process_scheduled_works+0xa70/0x1490
[ 2030.243320]  ? __pfx_process_scheduled_works+0x10/0x10
[ 2030.243340]  ? do_raw_spin_lock+0x130/0x300
[ 2030.243358]  ? lock_is_held_type+0x7b/0x110
[ 2030.243388]  worker_thread+0x932/0xe20
[ 2030.243415]  kthread+0x38a/0x470
[ 2030.243431]  ? __pfx_worker_thread+0x10/0x10
[ 2030.243451]  ? __pfx_kthread+0x10/0x10
[ 2030.243467]  ret_from_fork+0x484/0x910
[ 2030.243485]  ? __pfx_ret_from_fork+0x10/0x10
[ 2030.243501]  ? __switch_to+0xc77/0x12c0
[ 2030.243523]  ? __pfx_kthread+0x10/0x10
[ 2030.243540]  ret_from_fork_asm+0x1a/0x30
[ 2030.243564]  </TASK>
[ 2030.243570]
[ 2030.290164] Allocated by task 19279:
[ 2030.290911]  kasan_save_track+0x3e/0x80
[ 2030.292179]  __kasan_kmalloc+0x72/0x90
[ 2030.293217]  __kvmalloc_node_noprof+0x3ff/0x6b0
[ 2030.294467]  handle_generic_event+0x59b/0x750
[ 2030.295345]  genl_family_rcv_msg_doit+0x238/0x340
[ 2030.296553]  genl_rcv_msg+0x606/0x7b0
[ 2030.297129]  netlink_rcv_skb+0x22b/0x4a0
[ 2030.298500]  genl_rcv+0x2d/0x40
[ 2030.299273]  netlink_unicast+0x7ba/0x930
[ 2030.300019]  netlink_sendmsg+0x8c3/0xb00
[ 2030.301073]  __sock_sendmsg+0xec/0x140
[ 2030.301579]  __sys_sendto+0x357/0x470
[ 2030.302255]  __x64_sys_sendto+0xe3/0x100
[ 2030.303425]  do_syscall_64+0x135/0x460
[ 2030.304763]  entry_SYSCALL_64_after_hwframe+0x77/0x7f
[ 2030.305594]
[ 2030.305819] The buggy address belongs to the object at ffff888121bb6640
[ 2030.305819]  which belongs to the cache kmalloc-192 of size 192
[ 2030.309595] The buggy address is located 64 bytes inside of
[ 2030.309595]  allocated 166-byte region [ffff888121bb6640, ffff888121bb66e6)
[ 2030.312484]
[ 2030.312719] The buggy address belongs to the physical page:
[ 2030.314315] page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x121bb6
[ 2030.316481] head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
[ 2030.318248] flags: 0x100000000000040(head|node=0|zone=2)
[ 2030.319662] page_type: f5(slab)
[ 2030.320242] raw: 0100000000000040 ffff8881000424c0 ffffea00047c1510 ffff888100040468
[ 2030.321911] raw: 0000000000000000 0000000000150015 00000000f5000000 0000000000000000
[ 2030.324413] head: 0100000000000040 ffff8881000424c0 ffffea00047c1510 ffff888100040468
[ 2030.326150] head: 0000000000000000 0000000000150015 00000000f5000000 0000000000000000
[ 2030.327960] head: 0100000000000001 ffffffffffffff81 00000000ffffffff 00000000ffffffff
[ 2030.329615] head: ffff888121bb7ab0 0000000000000000 00000000ffffffff 0000000000000000
[ 2030.331861] page dumped because: kasan: bad access detected
[ 2030.332946]
[ 2030.333502] Memory state around the buggy address:
[ 2030.334698]  ffff888121bb6580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 2030.336475]  ffff888121bb6600: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
[ 2030.338143] >ffff888121bb6680: 00 00 00 00 00 00 00 00 00 00 00 00 06 fc fc fc
[ 2030.339116]                                                        ^
[ 2030.341315]  ffff888121bb6700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 2030.342801]  ffff888121bb6780: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
[ 2030.344643] ==================================================================

Found with ksmbdzzer [2], a KSMBD fuzzer that drives libFuzzer with a
kcov-dataflow [1] coverage vector: it folds each instrumented
comparison/argument's runtime operand value together with its PC (the
default arm mixes them as pc⊕val) so that a new operand value at a known
site counts as new coverage.

[1] https://lwn.net/Articles/1077606/
[2] https://github.com/yskzalloc/kcov-dataflow

Fixes: e2f34481b2 ("cifsd: add server-side procedures for SMB3")
Signed-off-by: Yunseong Kim <yunseong.kim@est.tech>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
2026-08-17 15:00:50 +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: fix slab-out-of-bounds read in ksmbd_alloc_user() 2026-08-17 15:00:50 +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