linux-cve-announce - CVE-2023-53624: net/sched: sch_fq: fix integer overflow of "credit"

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <2025100711-CVE-2023-53624-7a7c@gregkh>
Date: Tue,  7 Oct 2025 17:19:29 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-53624: net/sched: sch_fq: fix integer overflow of "credit"

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

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

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

net/sched: sch_fq: fix integer overflow of "credit"

if sch_fq is configured with "initial quantum" having values greater than
INT_MAX, the first assignment of "credit" does signed integer overflow to
a very negative value.
In this situation, the syzkaller script provided by Cristoph triggers the
CPU soft-lockup warning even with few sockets. It's not an infinite loop,
but "credit" wasn't probably meant to be minus 2Gb for each new flow.
Capping "initial quantum" to INT_MAX proved to fix the issue.

v2: validation of "initial quantum" is done in fq_policy, instead of open
    coding in fq_change() _ suggested by Jakub Kicinski

The Linux kernel CVE team has assigned CVE-2023-53624 to this issue.


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

	Issue introduced in 3.12 with commit afe4fd062416b158a8a8538b23adc1930a9b88dc and fixed in 5.10.180 with commit 4b8a05e3801661a0438fcd0cdef181030d966a5a
	Issue introduced in 3.12 with commit afe4fd062416b158a8a8538b23adc1930a9b88dc and fixed in 5.15.111 with commit d0b43125ec892aeb1b03e5df5aab595097da225a
	Issue introduced in 3.12 with commit afe4fd062416b158a8a8538b23adc1930a9b88dc and fixed in 6.1.28 with commit 4fbefeab88c6e79753a25099d455d3d59d2946b4
	Issue introduced in 3.12 with commit afe4fd062416b158a8a8538b23adc1930a9b88dc and fixed in 6.2.15 with commit 85f24cb2f10b2b0f2882e5786a09b4790bb3a0ad
	Issue introduced in 3.12 with commit afe4fd062416b158a8a8538b23adc1930a9b88dc and fixed in 6.3.2 with commit 2322462d6f9ad4874f4e3c63df3b5cc00cb1acbd
	Issue introduced in 3.12 with commit afe4fd062416b158a8a8538b23adc1930a9b88dc and fixed in 6.4 with commit 7041101ff6c3073fd8f2e99920f535b111c929cb

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-2023-53624
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_fq.c
	tools/testing/selftests/tc-testing/tc-tests/qdiscs/fq.json


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/4b8a05e3801661a0438fcd0cdef181030d966a5a
	https://git.kernel.org/stable/c/d0b43125ec892aeb1b03e5df5aab595097da225a
	https://git.kernel.org/stable/c/4fbefeab88c6e79753a25099d455d3d59d2946b4
	https://git.kernel.org/stable/c/85f24cb2f10b2b0f2882e5786a09b4790bb3a0ad
	https://git.kernel.org/stable/c/2322462d6f9ad4874f4e3c63df3b5cc00cb1acbd
	https://git.kernel.org/stable/c/7041101ff6c3073fd8f2e99920f535b111c929cb