cve/published/2025/CVE-2025-37913.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-2025-37913: net_sched: qfq: Fix double list add in class with netem as child qdisc

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

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

net_sched: qfq: Fix double list add in class with netem as child qdisc

As described in Gerrard's report [1], there are use cases where a netem
child qdisc will make the parent qdisc's enqueue callback reentrant.
In the case of qfq, there won't be a UAF, but the code will add the same
classifier to the list twice, which will cause memory corruption.

This patch checks whether the class was already added to the agg->active
list (cl_is_active) before doing the addition to cater for the reentrant
case.

[1] https://lore.kernel.org/netdev/CAHcdcOm+03OD2j6R0=YHKqmy=VgJ8xEOKuP6c7mSgnp-TEJJbw@mail.gmail.com/

The Linux kernel CVE team has assigned CVE-2025-37913 to this issue.


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

	Issue introduced in 5.0 with commit 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea and fixed in 5.4.294 with commit 041f410aec2c1751ee22b8b73ba05d38c3a6a602
	Issue introduced in 5.0 with commit 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea and fixed in 5.10.238 with commit 005a479540478a820c52de098e5e767e63e36f0a
	Issue introduced in 5.0 with commit 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea and fixed in 5.15.182 with commit 0bf32d6fb1fcbf841bb9945570e0e2a70072c00f
	Issue introduced in 5.0 with commit 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea and fixed in 6.1.138 with commit 0aa23e0856b7cedb3c88d8e3d281c212c7e4fbeb
	Issue introduced in 5.0 with commit 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea and fixed in 6.6.90 with commit a43783119e01849fbf2fe8855634e8989b240cb4
	Issue introduced in 5.0 with commit 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea and fixed in 6.12.28 with commit 53bc0b55178bd59bdd4bcd16349505cabf54b1a2
	Issue introduced in 5.0 with commit 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea and fixed in 6.14.6 with commit 370218e8ce711684acc4cdd3cc3c6dd7956bc165
	Issue introduced in 5.0 with commit 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea and fixed in 6.15 with commit f139f37dcdf34b67f5bf92bc8e0f7f6b3ac63aa4

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-2025-37913
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_qfq.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/041f410aec2c1751ee22b8b73ba05d38c3a6a602
	https://git.kernel.org/stable/c/005a479540478a820c52de098e5e767e63e36f0a
	https://git.kernel.org/stable/c/0bf32d6fb1fcbf841bb9945570e0e2a70072c00f
	https://git.kernel.org/stable/c/0aa23e0856b7cedb3c88d8e3d281c212c7e4fbeb
	https://git.kernel.org/stable/c/a43783119e01849fbf2fe8855634e8989b240cb4
	https://git.kernel.org/stable/c/53bc0b55178bd59bdd4bcd16349505cabf54b1a2
	https://git.kernel.org/stable/c/370218e8ce711684acc4cdd3cc3c6dd7956bc165
	https://git.kernel.org/stable/c/f139f37dcdf34b67f5bf92bc8e0f7f6b3ac63aa4