cve/published/2025/CVE-2025-37798.mbox

From bippy-1.2.0 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@kernel.org>
To: <linux-cve-announce@vger.kernel.org>
Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org>
Subject: CVE-2025-37798: codel: remove sch->q.qlen check before qdisc_tree_reduce_backlog()

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

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

codel: remove sch->q.qlen check before qdisc_tree_reduce_backlog()

After making all ->qlen_notify() callbacks idempotent, now it is safe to
remove the check of qlen!=0 from both fq_codel_dequeue() and
codel_qdisc_dequeue().

The Linux kernel CVE team has assigned CVE-2025-37798 to this issue.


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

	Issue introduced in 3.5 with commit 76e3cc126bb223013a6b9a0e2a51238d1ef2e409 and fixed in 6.1.135 with commit 829c49b6b2ff45b043739168fd1245e4e1a91a30
	Issue introduced in 3.5 with commit 76e3cc126bb223013a6b9a0e2a51238d1ef2e409 and fixed in 6.6.88 with commit 2f9761a94bae33d26e6a81b31b36e7d776d93dc1
	Issue introduced in 3.5 with commit 76e3cc126bb223013a6b9a0e2a51238d1ef2e409 and fixed in 6.12.24 with commit 4d55144b12e742404bb3f8fee6038bafbf45619d
	Issue introduced in 3.5 with commit 76e3cc126bb223013a6b9a0e2a51238d1ef2e409 and fixed in 6.13.12 with commit e73c838c80dccb9e4f19becc11d9f3cb4a27d483
	Issue introduced in 3.5 with commit 76e3cc126bb223013a6b9a0e2a51238d1ef2e409 and fixed in 6.14.3 with commit a57fe60ef4cf96bfbb6b58397ec28bdb5a5c6b31
	Issue introduced in 3.5 with commit 76e3cc126bb223013a6b9a0e2a51238d1ef2e409 and fixed in 6.15 with commit 342debc12183b51773b3345ba267e9263bdfaaef

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-2025-37798
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/sched/sch_codel.c
	net/sched/sch_fq_codel.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/829c49b6b2ff45b043739168fd1245e4e1a91a30
	https://git.kernel.org/stable/c/2f9761a94bae33d26e6a81b31b36e7d776d93dc1
	https://git.kernel.org/stable/c/4d55144b12e742404bb3f8fee6038bafbf45619d
	https://git.kernel.org/stable/c/e73c838c80dccb9e4f19becc11d9f3cb4a27d483
	https://git.kernel.org/stable/c/a57fe60ef4cf96bfbb6b58397ec28bdb5a5c6b31
	https://git.kernel.org/stable/c/342debc12183b51773b3345ba267e9263bdfaaef