linux-cve-announce - CVE-2022-49694: block: disable the elevator int del

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Message-ID: <2025022628-CVE-2022-49694-d7d9@gregkh>
Date: Wed, 26 Feb 2025 03:24:17 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2022-49694: block: disable the elevator int del_gendisk

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

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

block: disable the elevator int del_gendisk

The elevator is only used for file system requests, which are stopped in
del_gendisk.  Move disabling the elevator and freeing the scheduler tags
to the end of del_gendisk instead of doing that work in disk_release and
blk_cleanup_queue to avoid a use after free on q->tag_set from
disk_release as the tag_set might not be alive at that point.

Move the blk_qos_exit call as well, as it just depends on the elevator
exit and would be the only reason to keep the not exactly cheap queue
freeze in disk_release.

The Linux kernel CVE team has assigned CVE-2022-49694 to this issue.


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

	Issue introduced in 5.16 with commit e155b0c238b20f0a866f4334d292656665836c8a and fixed in 5.18.8 with commit f28699fafc047ec33299da01e928c3a0073c5cc6
	Issue introduced in 5.16 with commit e155b0c238b20f0a866f4334d292656665836c8a and fixed in 5.19 with commit 50e34d78815e474d410f342fbe783b18192ca518

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-2022-49694
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:
	block/blk-core.c
	block/genhd.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/f28699fafc047ec33299da01e928c3a0073c5cc6
	https://git.kernel.org/stable/c/50e34d78815e474d410f342fbe783b18192ca518