linux-cve-announce - CVE-2025-21641: mptcp: sysctl: blackhole timeout: avoid using current->nsproxy

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <2025011944-CVE-2025-21641-0897@gregkh>
Date: Sun, 19 Jan 2025 11:17:50 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2025-21641: mptcp: sysctl: blackhole timeout: avoid using current->nsproxy

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

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

mptcp: sysctl: blackhole timeout: avoid using current->nsproxy

As mentioned in the previous commit, using the 'net' structure via
'current' is not recommended for different reasons:

- Inconsistency: getting info from the reader's/writer's netns vs only
  from the opener's netns.

- current->nsproxy can be NULL in some cases, resulting in an 'Oops'
  (null-ptr-deref), e.g. when the current task is exiting, as spotted by
  syzbot [1] using acct(2).

The 'pernet' structure can be obtained from the table->data using
container_of().

The Linux kernel CVE team has assigned CVE-2025-21641 to this issue.


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

	Issue introduced in 6.12 with commit 27069e7cb3d1cea9377069266acf19b9cc5ad0ae and fixed in 6.12.10 with commit 4c74fbdc5ab95b13945be01e6065940b68222db7
	Issue introduced in 6.12 with commit 27069e7cb3d1cea9377069266acf19b9cc5ad0ae and fixed in 6.13-rc7 with commit 92cf7a51bdae24a32c592adcdd59a773ae149289

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-2025-21641
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/4c74fbdc5ab95b13945be01e6065940b68222db7
	https://git.kernel.org/stable/c/92cf7a51bdae24a32c592adcdd59a773ae149289