CVE-2021-46970

/// Technical description

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

bus: mhi: pci_generic: Remove WQ_MEM_RECLAIM flag from state workqueue

A recent change created a dedicated workqueue for the state-change work

with WQ_HIGHPRI (no strong reason for that) and WQ_MEM_RECLAIM flags,

but the state-change work (mhi_pm_st_worker) does not guarantee forward

progress under memory pressure, and will even wait on various memory

allocations when e.g. creating devices, loading firmware, etc... The

work is then not part of a memory reclaim path...

Moreover, this causes a warning in check_flush_dependency() since we end

up in code that flushes a non-reclaim workqueue:

[ 40.969601] workqueue: WQ_MEM_RECLAIM mhi_hiprio_wq:mhi_pm_st_worker [mhi] is flushing !WQ_MEM_RECLAIM events_highpri:flush_backlog

[ 40.969612] WARNING: CPU: 4 PID: 158 at kernel/workqueue.c:2607 check_flush_dependency+0x11c/0x140

[ 40.969733] Call Trace:

[ 40.969740] __flush_work+0x97/0x1d0

[ 40.969745] ? wake_up_pro

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References