CVE-2021-46970

CVE-2021-46970 is a medium-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 5.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

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_process+0x15/0x20 [ 40.969749] ? insert_work+0x70/0x80 [ 40.969750] ? __queue_work+0x14a/0x3e0 [ 40.969753] flush_work+0x10/0x20 [ 40.969756] rollback_registered_many+0x1c9/0x510 [ 40.969759] unregister_netdevice_queue+0x94/0x120 [ 40.969761] unregister_netdev+0x1d/0x30 [ 40.969765] mhi_net_remove+0x1a/0x40 [mhi_net] [ 40.969770] mhi_driver_remove+0x124/0x250 [mhi] [ 40.969776] device_release_driver_internal+0xf0/0x1d0 [ 40.969778] device_release_driver+0x12/0x20 [ 40.969782] bus_remove_device+0xe1/0x150 [ 40.969786] device_del+0x17b/0x3e0 [ 40.969791] mhi_destroy_device+0x9a/0x100 [mhi] [ 40.969796] ? mhi_unmap_single_use_bb+0x50/0x50 [mhi] [ 40.969799] device_for_each_child+0x5e/0xa0 [ 40.969804] mhi_pm_st_worker+0x921/0xf50 [mhi]

Frequently asked questions

What is CVE-2021-46970?
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_process+0x15/0x20 [ 40.969749] ? insert_work+0x70/0x80 [ 40.969750] ? __queue_work+0x14a/0x3e0 [ 40.969753] flush_work+0x10/0x20 [ 40.969756] rollback_registered_many+0x1c9/0x510 [ 40.969759] unregister_netdevice_queue+0x94/0x120 [ 40.969761] unregister_netdev+0x1d/0x30 [ 40.969765] mhi_net_remove+0x1a/0x40 [mhi_net] [ 40.969770] mhi_driver_remove+0x124/0x250 [mhi] [ 40.969776] device_release_driver_internal+0xf0/0x1d0 [ 40.969778] device_release_driver+0x12/0x20 [ 40.969782] bus_remove_device+0xe1/0x150 [ 40.969786] device_del+0x17b/0x3e0 [ 40.969791] mhi_destroy_device+0x9a/0x100 [mhi] [ 40.969796] ? mhi_unmap_single_use_bb+0x50/0x50 [mhi] [ 40.969799] device_for_each_child+0x5e/0xa0 [ 40.969804] mhi_pm_st_worker+0x921/0xf50 [mhi]
How severe is CVE-2021-46970?
CVE-2021-46970 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-46970 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-46970?
CVE-2021-46970 affects Linux Linux Kernel. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-46970?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2021-46970 have an EU (EUVD) identifier?
Yes. CVE-2021-46970 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-33618.
When was CVE-2021-46970 published?
CVE-2021-46970 was published on 2024-02-27 and last updated on 2026-06-17.

References

Affected products (1)

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