linux-cve-announce - CVE-2025-40328: smb: client: fix potential UAF in smb2_close_cached

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Message-ID: <2025120909-CVE-2025-40328-a95b@gregkh>
Date: Tue,  9 Dec 2025 13:10:10 +0900
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-40328: smb: client: fix potential UAF in smb2_close_cached_fid()

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

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

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

smb: client: fix potential UAF in smb2_close_cached_fid()

find_or_create_cached_dir() could grab a new reference after kref_put()
had seen the refcount drop to zero but before cfid_list_lock is acquired
in smb2_close_cached_fid(), leading to use-after-free.

Switch to kref_put_lock() so cfid_release() is called with
cfid_list_lock held, closing that gap.

The Linux kernel CVE team has assigned CVE-2025-40328 to this issue.


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

	Issue introduced in 6.1 with commit ebe98f1447bbccf8228335c62d86af02a0ed23f7 and fixed in 6.6.117 with commit cb52d9c86d70298de0ab7c7953653898cbc0efd6
	Issue introduced in 6.1 with commit ebe98f1447bbccf8228335c62d86af02a0ed23f7 and fixed in 6.12.58 with commit 065bd62412271a2d734810dd50336cae88c54427
	Issue introduced in 6.1 with commit ebe98f1447bbccf8228335c62d86af02a0ed23f7 and fixed in 6.17.8 with commit bdb596ceb4b7c3f28786a33840263728217fbcf5
	Issue introduced in 6.1 with commit ebe98f1447bbccf8228335c62d86af02a0ed23f7 and fixed in 6.18 with commit 734e99623c5b65bf2c03e35978a0b980ebc3c2f8

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-2025-40328
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/cached_dir.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/cb52d9c86d70298de0ab7c7953653898cbc0efd6
	https://git.kernel.org/stable/c/065bd62412271a2d734810dd50336cae88c54427
	https://git.kernel.org/stable/c/bdb596ceb4b7c3f28786a33840263728217fbcf5
	https://git.kernel.org/stable/c/734e99623c5b65bf2c03e35978a0b980ebc3c2f8