linux-cve-announce - CVE-2022-50552: blk-mq: use quiesced elevator switch when reinitializing queues

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Message-ID: <2025100759-CVE-2022-50552-5100@gregkh>
Date: Tue,  7 Oct 2025 17:21:10 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2022-50552: blk-mq: use quiesced elevator switch when reinitializing queues

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

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

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

blk-mq: use quiesced elevator switch when reinitializing queues

The hctx's run_work may be racing with the elevator switch when
reinitializing hardware queues. The queue is merely frozen in this
context, but that only prevents requests from allocating and doesn't
stop the hctx work from running. The work may get an elevator pointer
that's being torn down, and can result in use-after-free errors and
kernel panics (example below). Use the quiesced elevator switch instead,
and make the previous one static since it is now only used locally.

  nvme nvme0: resetting controller
  nvme nvme0: 32/0/0 default/read/poll queues
  BUG: kernel NULL pointer dereference, address: 0000000000000008
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 80000020c8861067 P4D 80000020c8861067 PUD 250f8c8067 PMD 0
  Oops: 0000 [#1] SMP PTI
  Workqueue: kblockd blk_mq_run_work_fn
  RIP: 0010:kyber_has_work+0x29/0x70

...

  Call Trace:
   __blk_mq_do_dispatch_sched+0x83/0x2b0
   __blk_mq_sched_dispatch_requests+0x12e/0x170
   blk_mq_sched_dispatch_requests+0x30/0x60
   __blk_mq_run_hw_queue+0x2b/0x50
   process_one_work+0x1ef/0x380
   worker_thread+0x2d/0x3e0

The Linux kernel CVE team has assigned CVE-2022-50552 to this issue.


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

	Fixed in 5.19.17 with commit 63a681bcc32a43528ce0f690569f7f48e59c3963
	Fixed in 6.0.3 with commit c478b3b2900f1834cf9eda5bfef0d5696099505d
	Fixed in 6.1 with commit 8237c01f1696bc53c470493bf1fe092a107648a6

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-2022-50552
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-mq.c
	block/blk.h
	block/elevator.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/63a681bcc32a43528ce0f690569f7f48e59c3963
	https://git.kernel.org/stable/c/c478b3b2900f1834cf9eda5bfef0d5696099505d
	https://git.kernel.org/stable/c/8237c01f1696bc53c470493bf1fe092a107648a6