linux-cve-announce - CVE-2025-40285: smb/server: fix possible refcount leak in smb2_sess

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Message-ID: <2025120718-CVE-2025-40285-9158@gregkh>
Date: Sun,  7 Dec 2025 06:52:32 +0900
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-40285: smb/server: fix possible refcount leak in smb2_sess_setup()

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

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

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

smb/server: fix possible refcount leak in smb2_sess_setup()

Reference count of ksmbd_session will leak when session need reconnect.
Fix this by adding the missing ksmbd_user_session_put().

The Linux kernel CVE team has assigned CVE-2025-40285 to this issue.


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

	Fixed in 6.1.159 with commit 6fc935f798d44a8eb8a5e6659198399fbf57b981
	Fixed in 6.6.117 with commit e671f9bb97805771380c98de944e2ceab6949188
	Fixed in 6.12.59 with commit dcc51dfe6ff26b52cac106865a172ac982d78401
	Fixed in 6.17.9 with commit d37b2c81c83d6c0d5ca582f4fe73c672983f9e0d
	Fixed in 6.18 with commit 379510a815cb2e64eb0a379cb62295d6ade65df0

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-2025-40285
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/server/smb2pdu.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/6fc935f798d44a8eb8a5e6659198399fbf57b981
	https://git.kernel.org/stable/c/e671f9bb97805771380c98de944e2ceab6949188
	https://git.kernel.org/stable/c/dcc51dfe6ff26b52cac106865a172ac982d78401
	https://git.kernel.org/stable/c/d37b2c81c83d6c0d5ca582f4fe73c672983f9e0d
	https://git.kernel.org/stable/c/379510a815cb2e64eb0a379cb62295d6ade65df0