linux-cve-announce - CVE-2025-68221: mptcp: fix address removal logic in mptcp_pm_nl_rm

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Message-ID: <2025121633-CVE-2025-68221-7f16@gregkh>
Date: Tue, 16 Dec 2025 14:57:40 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-68221: mptcp: fix address removal logic in mptcp_pm_nl_rm_addr

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

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

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

mptcp: fix address removal logic in mptcp_pm_nl_rm_addr

Fix inverted WARN_ON_ONCE condition that prevented normal address
removal counter updates. The current code only executes decrement
logic when the counter is already 0 (abnormal state), while
normal removals (counter > 0) are ignored.

The Linux kernel CVE team has assigned CVE-2025-68221 to this issue.


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

	Issue introduced in 6.15 with commit 63611391850850bf27f81afb0d0b6d1237a34006 and fixed in 6.17.10 with commit f7d953c38245c0e9d8e268fb6a9e524602fb44ec
	Issue introduced in 6.15 with commit 63611391850850bf27f81afb0d0b6d1237a34006 and fixed in 6.18 with commit 92e239e36d600002559074994a545fcfac9afd2d

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-2025-68221
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:
	net/mptcp/pm_kernel.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/f7d953c38245c0e9d8e268fb6a9e524602fb44ec
	https://git.kernel.org/stable/c/92e239e36d600002559074994a545fcfac9afd2d