linux-cve-announce - CVE-2024-57888: workqueue: Do not warn when cancelling WQ_MEM_RECLAIM work from !WQ_MEM

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Message-ID: <2025011511-CVE-2024-57888-0b38@gregkh>
Date: Wed, 15 Jan 2025 14:06:11 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-57888: workqueue: Do not warn when cancelling WQ_MEM_RECLAIM work from !WQ_MEM_RECLAIM worker

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

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

workqueue: Do not warn when cancelling WQ_MEM_RECLAIM work from !WQ_MEM_RECLAIM worker

After commit
746ae46c1113 ("drm/sched: Mark scheduler work queues with WQ_MEM_RECLAIM")
amdgpu started seeing the following warning:

 [ ] workqueue: WQ_MEM_RECLAIM sdma0:drm_sched_run_job_work [gpu_sched] is flushing !WQ_MEM_RECLAIM events:amdgpu_device_delay_enable_gfx_off [amdgpu]
...
 [ ] Workqueue: sdma0 drm_sched_run_job_work [gpu_sched]
...
 [ ] Call Trace:
 [ ]  <TASK>
...
 [ ]  ? check_flush_dependency+0xf5/0x110
...
 [ ]  cancel_delayed_work_sync+0x6e/0x80
 [ ]  amdgpu_gfx_off_ctrl+0xab/0x140 [amdgpu]
 [ ]  amdgpu_ring_alloc+0x40/0x50 [amdgpu]
 [ ]  amdgpu_ib_schedule+0xf4/0x810 [amdgpu]
 [ ]  ? drm_sched_run_job_work+0x22c/0x430 [gpu_sched]
 [ ]  amdgpu_job_run+0xaa/0x1f0 [amdgpu]
 [ ]  drm_sched_run_job_work+0x257/0x430 [gpu_sched]
 [ ]  process_one_work+0x217/0x720
...
 [ ]  </TASK>

The intent of the verifcation done in check_flush_depedency is to ensure
forward progress during memory reclaim, by flagging cases when either a
memory reclaim process, or a memory reclaim work item is flushed from a
context not marked as memory reclaim safe.

This is correct when flushing, but when called from the
cancel(_delayed)_work_sync() paths it is a false positive because work is
either already running, or will not be running at all. Therefore
cancelling it is safe and we can relax the warning criteria by letting the
helper know of the calling context.

References: 746ae46c1113 ("drm/sched: Mark scheduler work queues with WQ_MEM_RECLAIM")

The Linux kernel CVE team has assigned CVE-2024-57888 to this issue.


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

	Issue introduced in 4.5 with commit fca839c00a12d682cb59b3b620d109a1d850b262 and fixed in 6.12.9 with commit ffb231471a407c96e114070bf828cd2378fdf431
	Issue introduced in 4.5 with commit fca839c00a12d682cb59b3b620d109a1d850b262 and fixed in 6.13-rc6 with commit de35994ecd2dd6148ab5a6c5050a1670a04dec77

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-2024-57888
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:
	kernel/workqueue.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/ffb231471a407c96e114070bf828cd2378fdf431
	https://git.kernel.org/stable/c/de35994ecd2dd6148ab5a6c5050a1670a04dec77