linux-cve-announce - CVE-2025-21635: rds: sysctl: rds_tcp_{rcv,snd}buf: avoid using current->nsproxy

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Message-ID: <2025011943-CVE-2025-21635-12e7@gregkh>
Date: Sun, 19 Jan 2025 11:17:44 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2025-21635: rds: sysctl: rds_tcp_{rcv,snd}buf: avoid using current->nsproxy

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

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

rds: sysctl: rds_tcp_{rcv,snd}buf: 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 per-netns structure can be obtained from the table->data using
container_of(), then the 'net' one can be retrieved from the listen
socket (if available).

The Linux kernel CVE team has assigned CVE-2025-21635 to this issue.


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

	Issue introduced in 4.6 with commit c6a58ffed53612be86b758df1cdb0b0f4305e9cb and fixed in 6.12.10 with commit de8d6de0ee27be4b2b1e5b06f04aeacbabbba492
	Issue introduced in 4.6 with commit c6a58ffed53612be86b758df1cdb0b0f4305e9cb and fixed in 6.13-rc7 with commit 7f5611cbc4871c7fb1ad36c2e5a9edad63dca95c

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-2025-21635
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/rds/tcp.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/de8d6de0ee27be4b2b1e5b06f04aeacbabbba492
	https://git.kernel.org/stable/c/7f5611cbc4871c7fb1ad36c2e5a9edad63dca95c