Hyunwoo Kim c33615f995 ksmbd: fix use-after-free of share_conf in compound request
smb2_get_ksmbd_tcon() reuses work->tcon in compound requests without
validating tcon->t_state. ksmbd_tree_conn_lookup() checks t_state ==
TREE_CONNECTED on the initial lookup path, but the compound reuse path
bypasses this check entirely.

If a prior command in the compound (SMB2_TREE_DISCONNECT) sets t_state
to TREE_DISCONNECTED and frees share_conf via ksmbd_share_config_put(),
subsequent commands dereference the freed share_conf through
work->tcon->share_conf.

KASAN report:

[    4.144653] ==================================================================
[    4.145059] BUG: KASAN: slab-use-after-free in smb2_write+0xc74/0xe70
[    4.145415] Read of size 4 at addr ffff88810430c194 by task kworker/1:1/44
[    4.145772]
[    4.145867] CPU: 1 UID: 0 PID: 44 Comm: kworker/1:1 Not tainted 7.0.0-rc3+ #60 PREEMPTLAZY
[    4.145871] Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[    4.145875] Workqueue: ksmbd-io handle_ksmbd_work
[    4.145888] Call Trace:
[    4.145892]  <TASK>
[    4.145894]  dump_stack_lvl+0x64/0x80
[    4.145910]  print_report+0xce/0x660
[    4.145919]  ? __pfx__raw_spin_lock_irqsave+0x10/0x10
[    4.145928]  ? smb2_write+0xc74/0xe70
[    4.145931]  kasan_report+0xce/0x100
[    4.145934]  ? smb2_write+0xc74/0xe70
[    4.145937]  smb2_write+0xc74/0xe70
[    4.145939]  ? __pfx_smb2_write+0x10/0x10
[    4.145942]  ? _raw_spin_unlock+0xe/0x30
[    4.145945]  ? ksmbd_smb2_check_message+0xeb2/0x24c0
[    4.145948]  ? smb2_tree_disconnect+0x31c/0x480
[    4.145951]  handle_ksmbd_work+0x40f/0x1080
[    4.145953]  process_one_work+0x5fa/0xef0
[    4.145962]  ? assign_work+0x122/0x3e0
[    4.145964]  worker_thread+0x54b/0xf70
[    4.145967]  ? __pfx_worker_thread+0x10/0x10
[    4.145970]  kthread+0x346/0x470
[    4.145976]  ? recalc_sigpending+0x19b/0x230
[    4.145980]  ? __pfx_kthread+0x10/0x10
[    4.145984]  ret_from_fork+0x4fb/0x6c0
[    4.145992]  ? __pfx_ret_from_fork+0x10/0x10
[    4.145995]  ? __switch_to+0x36c/0xbe0
[    4.145999]  ? __pfx_kthread+0x10/0x10
[    4.146003]  ret_from_fork_asm+0x1a/0x30
[    4.146013]  </TASK>
[    4.146014]
[    4.149858] Allocated by task 44:
[    4.149953]  kasan_save_stack+0x33/0x60
[    4.150061]  kasan_save_track+0x14/0x30
[    4.150169]  __kasan_kmalloc+0x8f/0xa0
[    4.150274]  ksmbd_share_config_get+0x1dd/0xdd0
[    4.150401]  ksmbd_tree_conn_connect+0x7e/0x600
[    4.150529]  smb2_tree_connect+0x2e6/0x1000
[    4.150645]  handle_ksmbd_work+0x40f/0x1080
[    4.150761]  process_one_work+0x5fa/0xef0
[    4.150873]  worker_thread+0x54b/0xf70
[    4.150978]  kthread+0x346/0x470
[    4.151071]  ret_from_fork+0x4fb/0x6c0
[    4.151176]  ret_from_fork_asm+0x1a/0x30
[    4.151286]
[    4.151332] Freed by task 44:
[    4.151418]  kasan_save_stack+0x33/0x60
[    4.151526]  kasan_save_track+0x14/0x30
[    4.151634]  kasan_save_free_info+0x3b/0x60
[    4.151751]  __kasan_slab_free+0x43/0x70
[    4.151861]  kfree+0x1ca/0x430
[    4.151952]  __ksmbd_tree_conn_disconnect+0xc8/0x190
[    4.152088]  smb2_tree_disconnect+0x1cd/0x480
[    4.152211]  handle_ksmbd_work+0x40f/0x1080
[    4.152326]  process_one_work+0x5fa/0xef0
[    4.152438]  worker_thread+0x54b/0xf70
[    4.152545]  kthread+0x346/0x470
[    4.152638]  ret_from_fork+0x4fb/0x6c0
[    4.152743]  ret_from_fork_asm+0x1a/0x30
[    4.152853]
[    4.152900] The buggy address belongs to the object at ffff88810430c180
[    4.152900]  which belongs to the cache kmalloc-96 of size 96
[    4.153226] The buggy address is located 20 bytes inside of
[    4.153226]  freed 96-byte region [ffff88810430c180, ffff88810430c1e0)
[    4.153549]
[    4.153596] The buggy address belongs to the physical page:
[    4.153750] page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88810430ce80 pfn:0x10430c
[    4.154000] flags: 0x100000000000200(workingset|node=0|zone=2)
[    4.154160] page_type: f5(slab)
[    4.154251] raw: 0100000000000200 ffff888100041280 ffff888100040110 ffff888100040110
[    4.154461] raw: ffff88810430ce80 0000000800200009 00000000f5000000 0000000000000000
[    4.154668] page dumped because: kasan: bad access detected
[    4.154820]
[    4.154866] Memory state around the buggy address:
[    4.155002]  ffff88810430c080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[    4.155196]  ffff88810430c100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[    4.155391] >ffff88810430c180: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
[    4.155587]                          ^
[    4.155693]  ffff88810430c200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[    4.155891]  ffff88810430c280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[    4.156087] ==================================================================

Add the same t_state validation to the compound reuse path, consistent
with ksmbd_tree_conn_lookup().

Fixes: 5005bcb421 ("ksmbd: validate session id and tree id in the compound request")
Signed-off-by: Hyunwoo Kim <imv4bel@gmail.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
2026-03-17 21:45:29 -05:00
2026-01-26 19:07:09 -08:00
2022-09-28 09:02:20 +02:00
2025-02-19 14:53:27 -07:00
2026-03-15 13:52:05 -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
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