linux-cve-announce - CVE-2022-49406: block: Fix potential deadlock in blk_ia_range_sysfs

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Message-ID: <2025022651-CVE-2022-49406-8378@gregkh>
Date: Wed, 26 Feb 2025 03:11:20 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2022-49406: block: Fix potential deadlock in blk_ia_range_sysfs_show()

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

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

block: Fix potential deadlock in blk_ia_range_sysfs_show()

When being read, a sysfs attribute is already protected against removal
with the kobject node active reference counter. As a result, in
blk_ia_range_sysfs_show(), there is no need to take the queue sysfs
lock when reading the value of a range attribute. Using the queue sysfs
lock in this function creates a potential deadlock situation with the
disk removal, something that a lockdep signals with a splat when the
device is removed:

[  760.703551]  Possible unsafe locking scenario:
[  760.703551]
[  760.703554]        CPU0                    CPU1
[  760.703556]        ----                    ----
[  760.703558]   lock(&q->sysfs_lock);
[  760.703565]                                lock(kn->active#385);
[  760.703573]                                lock(&q->sysfs_lock);
[  760.703579]   lock(kn->active#385);
[  760.703587]
[  760.703587]  *** DEADLOCK ***

Solve this by removing the mutex_lock()/mutex_unlock() calls from
blk_ia_range_sysfs_show().

The Linux kernel CVE team has assigned CVE-2022-49406 to this issue.


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

	Issue introduced in 5.16 with commit a2247f19ee1c5ad75ef095cdfb909a3244b88aa8 and fixed in 5.17.14 with commit dc107c805cde709866b59867ef72b9390199205e
	Issue introduced in 5.16 with commit a2247f19ee1c5ad75ef095cdfb909a3244b88aa8 and fixed in 5.18.3 with commit 717b078bc745ba9a262abebed9806a17e8bbb77b
	Issue introduced in 5.16 with commit a2247f19ee1c5ad75ef095cdfb909a3244b88aa8 and fixed in 5.19 with commit 41e46b3c2aa24f755b2ae9ec4ce931ba5f0d8532

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-2022-49406
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-ia-ranges.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/dc107c805cde709866b59867ef72b9390199205e
	https://git.kernel.org/stable/c/717b078bc745ba9a262abebed9806a17e8bbb77b
	https://git.kernel.org/stable/c/41e46b3c2aa24f755b2ae9ec4ce931ba5f0d8532