linux-cve-announce - CVE-2025-39826: net: rose: convert 'use' field to refcount

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Message-ID: <2025091616-CVE-2025-39826-e096@gregkh>
Date: Tue, 16 Sep 2025 15:00:32 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-39826: net: rose: convert 'use' field to refcount_t

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

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

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

net: rose: convert 'use' field to refcount_t

The 'use' field in struct rose_neigh is used as a reference counter but
lacks atomicity. This can lead to race conditions where a rose_neigh
structure is freed while still being referenced by other code paths.

For example, when rose_neigh->use becomes zero during an ioctl operation
via rose_rt_ioctl(), the structure may be removed while its timer is
still active, potentially causing use-after-free issues.

This patch changes the type of 'use' from unsigned short to refcount_t and
updates all code paths to use rose_neigh_hold() and rose_neigh_put() which
operate reference counts atomically.

The Linux kernel CVE team has assigned CVE-2025-39826 to this issue.


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

	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.1.150 with commit fb07156cc0742ba4e93dfcc84280c011d05b301f
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.6.104 with commit f8c29fc437d03a98fb075c31c5be761cc8326284
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.12.45 with commit 0085b250fcc79f900c82a69980ec2f3e1871823b
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.16.5 with commit 203e4f42596ede31498744018716a3db6dbb7f51
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.17-rc4 with commit d860d1faa6b2ce3becfdb8b0c2b048ad31800061

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-2025-39826
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:
	include/net/rose.h
	net/rose/af_rose.c
	net/rose/rose_in.c
	net/rose/rose_route.c
	net/rose/rose_timer.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/fb07156cc0742ba4e93dfcc84280c011d05b301f
	https://git.kernel.org/stable/c/f8c29fc437d03a98fb075c31c5be761cc8326284
	https://git.kernel.org/stable/c/0085b250fcc79f900c82a69980ec2f3e1871823b
	https://git.kernel.org/stable/c/203e4f42596ede31498744018716a3db6dbb7f51
	https://git.kernel.org/stable/c/d860d1faa6b2ce3becfdb8b0c2b048ad31800061