linux-cve-announce - CVE-2025-21637: sctp: sysctl: udp

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Message-ID: <2025011943-CVE-2025-21637-3dde@gregkh>
Date: Sun, 19 Jan 2025 11:17:46 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2025-21637: sctp: sysctl: udp_port: avoid using current->nsproxy

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

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

sctp: sysctl: udp_port: avoid using current->nsproxy

As mentioned in a previous commit of this series, 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 'net' structure can be obtained from the table->data using
container_of().

Note that table->data could also be used directly, but that would
increase the size of this fix, while 'sctp.ctl_sock' still needs to be
retrieved from 'net' structure.

The Linux kernel CVE team has assigned CVE-2025-21637 to this issue.


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

	Issue introduced in 5.11 with commit 046c052b475e7119b6a30e3483e2888fc606a2f8 and fixed in 6.1.125 with commit e919197fb8616331f5dc81e4c3cc3d12769cb725
	Issue introduced in 5.11 with commit 046c052b475e7119b6a30e3483e2888fc606a2f8 and fixed in 6.6.72 with commit 55627918febdf9d71107a1e68d1528dc591c9a15
	Issue introduced in 5.11 with commit 046c052b475e7119b6a30e3483e2888fc606a2f8 and fixed in 6.12.10 with commit 5b77d73f3be5102720fb685b9e6900e3500e1096
	Issue introduced in 5.11 with commit 046c052b475e7119b6a30e3483e2888fc606a2f8 and fixed in 6.13-rc7 with commit c10377bbc1972d858eaf0ab366a311b39f8ef1b6

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-2025-21637
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/sctp/sysctl.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/e919197fb8616331f5dc81e4c3cc3d12769cb725
	https://git.kernel.org/stable/c/55627918febdf9d71107a1e68d1528dc591c9a15
	https://git.kernel.org/stable/c/5b77d73f3be5102720fb685b9e6900e3500e1096
	https://git.kernel.org/stable/c/c10377bbc1972d858eaf0ab366a311b39f8ef1b6