linux-cve-announce - CVE-2025-40133: mptcp: Use __sk_dst_get() and dst_dev_rcu() in mptcp_active

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Message-ID: <2025111254-CVE-2025-40133-4d9d@gregkh>
Date: Wed, 12 Nov 2025 19:24:09 +0900
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-40133: mptcp: Use __sk_dst_get() and dst_dev_rcu() in mptcp_active_enable().

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

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

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

mptcp: Use __sk_dst_get() and dst_dev_rcu() in mptcp_active_enable().

mptcp_active_enable() is called from subflow_finish_connect(),
which is icsk->icsk_af_ops->sk_rx_dst_set() and it's not always
under RCU.

Using sk_dst_get(sk)->dev could trigger UAF.

Let's use __sk_dst_get() and dst_dev_rcu().

The Linux kernel CVE team has assigned CVE-2025-40133 to this issue.

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

	Issue introduced in 6.12 with commit 27069e7cb3d1cea9377069266acf19b9cc5ad0ae and fixed in 6.12.55 with commit ad16235c9d3ef7ec17c109ff39b7504f49d17072
	Issue introduced in 6.12 with commit 27069e7cb3d1cea9377069266acf19b9cc5ad0ae and fixed in 6.17.3 with commit cc976ec9e38bb79409de3261ba1dbb6868e2a53e
	Issue introduced in 6.12 with commit 27069e7cb3d1cea9377069266acf19b9cc5ad0ae and fixed in 6.18-rc1 with commit 893c49a78d9f85e4b8081b908fb7c407d018106a

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-2025-40133
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/ctrl.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/ad16235c9d3ef7ec17c109ff39b7504f49d17072
	https://git.kernel.org/stable/c/cc976ec9e38bb79409de3261ba1dbb6868e2a53e
	https://git.kernel.org/stable/c/893c49a78d9f85e4b8081b908fb7c407d018106a