linux-cve-announce - CVE-2026-23205: smb/client: fix memory leak in smb2_open

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Message-ID: <2026021438-CVE-2026-23205-a62a@gregkh>
Date: Sat, 14 Feb 2026 17:29:02 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2026-23205: smb/client: fix memory leak in smb2_open_file()

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

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

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

smb/client: fix memory leak in smb2_open_file()

Reproducer:

  1. server: directories are exported read-only
  2. client: mount -t cifs //${server_ip}/export /mnt
  3. client: dd if=/dev/zero of=/mnt/file bs=512 count=1000 oflag=direct
  4. client: umount /mnt
  5. client: sleep 1
  6. client: modprobe -r cifs

The error message is as follows:

  =============================================================================
  BUG cifs_small_rq (Not tainted): Objects remaining on __kmem_cache_shutdown()
  -----------------------------------------------------------------------------

  Object 0x00000000d47521be @offset=14336
  ...
  WARNING: mm/slub.c:1251 at __kmem_cache_shutdown+0x34e/0x440, CPU#0: modprobe/1577
  ...
  Call Trace:
   <TASK>
   kmem_cache_destroy+0x94/0x190
   cifs_destroy_request_bufs+0x3e/0x50 [cifs]
   cleanup_module+0x4e/0x540 [cifs]
   __se_sys_delete_module+0x278/0x400
   __x64_sys_delete_module+0x5f/0x70
   x64_sys_call+0x2299/0x2ff0
   do_syscall_64+0x89/0x350
   entry_SYSCALL_64_after_hwframe+0x76/0x7e
  ...
  kmem_cache_destroy cifs_small_rq: Slab cache still has objects when called from cifs_destroy_request_bufs+0x3e/0x50 [cifs]
  WARNING: mm/slab_common.c:532 at kmem_cache_destroy+0x16b/0x190, CPU#0: modprobe/1577

The Linux kernel CVE team has assigned CVE-2026-23205 to this issue.


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

	Issue introduced in 6.1.141 with commit 17e53a15e64b65623b8f2b1185d27d7b1cbf69ab and fixed in 6.1.163 with commit 743f70406264348c0830f38409eb6c40a42fb2db
	Issue introduced in 6.6.93 with commit 18066188eb90cc0c798f3370a8078a79ddb73f70 and fixed in 6.6.124 with commit 3a6d6b332f92990958602c1e35ce0173e2dd62e9
	Issue introduced in 6.12.31 with commit 6ebb9d54eccc8026b386e76eff69364d33373da5 and fixed in 6.12.70 with commit b64e3b5d8d759dd4333992e4ba4dadf9359952c8
	Issue introduced in 6.15 with commit e255612b5ed9f179abe8196df7c2ba09dd227900 and fixed in 6.18.10 with commit 9ee608a64e37cea5b4b13e436c559dd0fb2ad1b5
	Issue introduced in 6.15 with commit e255612b5ed9f179abe8196df7c2ba09dd227900 and fixed in 6.19 with commit e3a43633023e3cacaca60d4b8972d084a2b06236
	Issue introduced in 6.14.9 with commit bcd15f06c7e8904116cfb06526bcc189b86aff85

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-2026-23205
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/smb/client/smb2file.c


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/743f70406264348c0830f38409eb6c40a42fb2db
	https://git.kernel.org/stable/c/3a6d6b332f92990958602c1e35ce0173e2dd62e9
	https://git.kernel.org/stable/c/b64e3b5d8d759dd4333992e4ba4dadf9359952c8
	https://git.kernel.org/stable/c/9ee608a64e37cea5b4b13e436c559dd0fb2ad1b5
	https://git.kernel.org/stable/c/e3a43633023e3cacaca60d4b8972d084a2b06236