linux-cve-announce - CVE-2023-54203: ksmbd: fix slab-out-of-bounds in init_smb2_rsp

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Message-ID: <2025123031-CVE-2023-54203-b19c@gregkh>
Date: Tue, 30 Dec 2025 13:10:11 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-54203: ksmbd: fix slab-out-of-bounds in init_smb2_rsp_hdr

From: Greg Kroah-Hartman <gregkh@...nel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

ksmbd: fix slab-out-of-bounds in init_smb2_rsp_hdr

When smb1 mount fails, KASAN detect slab-out-of-bounds in
init_smb2_rsp_hdr like the following one.
For smb1 negotiate(56bytes) , init_smb2_rsp_hdr() for smb2 is called.
The issue occurs while handling smb1 negotiate as smb2 server operations.
Add smb server operations for smb1 (get_cmd_val, init_rsp_hdr,
allocate_rsp_buf, check_user_session) to handle smb1 negotiate so that
smb2 server operation does not handle it.

[  411.400423] CIFS: VFS: Use of the less secure dialect vers=1.0 is
not recommended unless required for access to very old servers
[  411.400452] CIFS: Attempting to mount \\192.168.45.139\homes
[  411.479312] ksmbd: init_smb2_rsp_hdr : 492
[  411.479323] ==================================================================
[  411.479327] BUG: KASAN: slab-out-of-bounds in
init_smb2_rsp_hdr+0x1e2/0x1f4 [ksmbd]
[  411.479369] Read of size 16 at addr ffff888488ed0734 by task kworker/14:1/199

[  411.479379] CPU: 14 PID: 199 Comm: kworker/14:1 Tainted: G
 OE      6.1.21 #3
[  411.479386] Hardware name: ASUSTeK COMPUTER INC. Z10PA-D8
Series/Z10PA-D8 Series, BIOS 3801 08/23/2019
[  411.479390] Workqueue: ksmbd-io handle_ksmbd_work [ksmbd]
[  411.479425] Call Trace:
[  411.479428]  <TASK>
[  411.479432]  dump_stack_lvl+0x49/0x63
[  411.479444]  print_report+0x171/0x4a8
[  411.479452]  ? kasan_complete_mode_report_info+0x3c/0x200
[  411.479463]  ? init_smb2_rsp_hdr+0x1e2/0x1f4 [ksmbd]
[  411.479497]  kasan_report+0xb4/0x130
[  411.479503]  ? init_smb2_rsp_hdr+0x1e2/0x1f4 [ksmbd]
[  411.479537]  kasan_check_range+0x149/0x1e0
[  411.479543]  memcpy+0x24/0x70
[  411.479550]  init_smb2_rsp_hdr+0x1e2/0x1f4 [ksmbd]
[  411.479585]  handle_ksmbd_work+0x109/0x760 [ksmbd]
[  411.479616]  ? _raw_spin_unlock_irqrestore+0x50/0x50
[  411.479624]  ? smb3_encrypt_resp+0x340/0x340 [ksmbd]
[  411.479656]  process_one_work+0x49c/0x790
[  411.479667]  worker_thread+0x2b1/0x6e0
[  411.479674]  ? process_one_work+0x790/0x790
[  411.479680]  kthread+0x177/0x1b0
[  411.479686]  ? kthread_complete_and_exit+0x30/0x30
[  411.479692]  ret_from_fork+0x22/0x30
[  411.479702]  </TASK>

The Linux kernel CVE team has assigned CVE-2023-54203 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.15.105 with commit 51a8534c0f35c0401e45f1055f914729cad98bf9 and fixed in 5.15.145 with commit 921536046bd165efeb07beef5630aff35cd6a489
	Issue introduced in 6.1.22 with commit 0b3ec5671ac06829ccebdaeec05acedfec327f42 and fixed in 6.1.24 with commit a8334a0c535d0f0b4d64926c8fe0922ed98f7d43
	Issue introduced in 6.2.9 with commit cc32cd98a0aee4cc3eb611cbce11795b1aaa738a and fixed in 6.2.11 with commit 99a51c673b1d2d0b5a972353401b77612d9cc713

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2023-54203
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	fs/ksmbd/server.c
	fs/ksmbd/smb2pdu.c
	fs/ksmbd/smb_common.c
	fs/ksmbd/smb_common.h


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/921536046bd165efeb07beef5630aff35cd6a489
	https://git.kernel.org/stable/c/a8334a0c535d0f0b4d64926c8fe0922ed98f7d43
	https://git.kernel.org/stable/c/99a51c673b1d2d0b5a972353401b77612d9cc713
	https://git.kernel.org/stable/c/dc8289f912387c3bcfbc5d2db29c8947fa207c11