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Response snapshot Oct 30, 2026, 17:36 UTC

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VulnerabilityCVE-2026-90301

Linux kernel: ocfs2: o2hb: quiesce negotiate handlers and timeout work

In the Linux kernel, the following vulnerability has been resolved: ocfs2: o2hb: quiesce negotiate handlers and timeout work Heartbeat regions publish struct o2hb_region as the private data for the NEGO_TIMEOUT and NEGO_APPROVE o2net handlers as soon as make_item() creates the configfs region.

At a glance

Exploited
Not known
Severity
8.1 High (CVSS 3.1)
Chance of exploitation
0.6% in the next 30 days
Sources
1 source

What to do

Check the vendor advisory for affected versions and fixes.

Read NVD CVE-2026-90301 (opens a new tab)

What happened

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

ocfs2: o2hb: quiesce negotiate handlers and timeout work

Heartbeat regions publish struct o2hb_region as the private data for the NEGO_TIMEOUT and NEGO_APPROVE o2net handlers as soon as make_item() creates the configfs region. The approve handler can call o2hb_arm_timeout(), so a peer can touch the region timeout work before dev_store() has finished building the heartbeat runtime, or after teardown has started to shut that runtime back down.

The final configfs put also has to keep reg alive until the last in-flight o2net callback drops its handler reference. o2net_unregister_handler_list() blocks future handler lookups, but it does not wait for sc_rx_work that already passed o2net_handler_get(). That drain needs to cover local listener teardown as well, where the o2net ordered workqueue may already be inside destroy_workqueue().

Continue reading

Fix the lifetime rule in both directions. Initialize the region delayed works before publishing reg through the o2net handler table, keep new or stopping regions non-armable with hr_stopping, and quiesce both delayed works on failed-start and teardown paths even when no heartbeat thread is left to call o2hb_disarm_timeout().

Then unregister handlers before tearing down handler-visible region state and make the drain wait for the active or destroying o2net ordered workqueue before release frees reg.

The buggy scenario involves two paths, with each column showing the order within that path:

region lifecycle: late negotiate callback: 1. make_item() registers the 1. o2net_process_message() gets a region handlers before heartbeat handler for reg. dev_store() has built a 2. The callback runs after the lookup runnable heartbeat context. lock is dropped and dereferences reg. 2. A failed start or rmdir 3.

An approve or timeout path tries to stops the heartbeat thread, queue reg's delayed work, or release quiesces existing work, and races the callback body after handler drops the final configfs ref. unregister. 3. region_release() must drain 4. The callback or delayed work can handler-visible o2net rx work outlive reg unless lifecycle code before freeing reg.

keeps the region non-armable and drains the active-or-destroying o2net workqueue.

Validation reproduced this kernel report: KASAN slab-use-after-free in __run_timers+0x22c/0x5b0 Write of size 8 Call trace: dump_stack_lvl+0x66/0xa0 print_report+0xce/0x630 __run_timers+0x22c/0x5b0 kasan_report+0xe0/0x110 _raw_spin_unlock_irqrestore+0x27/0x60 try_to_wake_up+0x191/0xf70 timer_expire_remote+0xae/0xf0 run_timer_softirq+0x19b/0x1a0 handle_softirqs+0x156/0x660 __irq_exit_rcu+0xc4/0x160 irq_exit_rcu+0xe/0x20 sysvec_apic_timer_interrupt+0x6c/0x80 asm_sysvec_apic_timer_interrupt+0x1a/0x20

Allocated by task stack: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 __kasan_kmalloc+0xaa/0xb0 o2hb_heartbeat_group_make_item+0x3c/0x600

Scores and how they were measured

CVSS base severity

8.1

Version 3.1As of

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

0.6%

Scored Percentile 46.1%

Model and measurement source (opens a new tab)

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    NVD CVE-2026-90301 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  2. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  3. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  4. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  5. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-90301, scored 2026-10-30. This is a model estimate, not proof of exposure.

    Published Checked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 30). Linux kernel: ocfs2: o2hb: quiesce negotiate handlers and timeout work (CVE-2026-90301). https://kevwire.com/record/CVE-2026-90301

MLA

"Linux kernel: ocfs2: o2hb: quiesce negotiate handlers and timeout work (CVE-2026-90301)." KEVWire, 30 Oct. 2026, kevwire.com/record/CVE-2026-90301.

Chicago

KEVWire. "Linux kernel: ocfs2: o2hb: quiesce negotiate handlers and timeout work (CVE-2026-90301)." Last modified October 30, 2026. https://kevwire.com/record/CVE-2026-90301.

Evidence summary (plain text)

Linux kernel: ocfs2: o2hb: quiesce negotiate handlers and timeout work (Sep 17, 2026).
In the Linux kernel, the following vulnerability has been resolved:

ocfs2: o2hb: quiesce negotiate handlers and timeout work

Heartbeat regions publish struct o2hb_region as the private data for the
NEGO_TIMEOUT and NEGO_APPROVE o2net handlers as soon as make_item()
creates the configfs region.  The approve handler can call
o2hb_arm_timeout(), so a peer can touch the region timeout work before
dev_store() has finished building the heartbeat runtime, or after teardown
has started to shut that runtime back down.
CVSS 8.1 (version 3.1; evidence as of Oct 30, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-90301).
EPSS 0.6% for the following 30 days, scored Oct 30, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-90301&date=2026-10-30).
Sources:
NVD CVE-2026-90301: https://nvd.nist.gov/vuln/detail/CVE-2026-90301
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-30T13:06:45.042Z&lastModEndDate=2026-10-30T14:50:57.069Z&resultsPerPage=500&startIndex=1000
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-30T12:22:16.957Z&lastModEndDate=2026-10-30T14:05:57.373Z&resultsPerPage=500&startIndex=500
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-30T11:45:59.009Z&lastModEndDate=2026-10-30T13:20:57.281Z&resultsPerPage=500&startIndex=500
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-90301&date=2026-10-30
Record ID: CVE-2026-90301.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 30, 2026, 14:52 UTC. Ingestion is not an independent editorial investigation.

NVD status: Received. Publication in the NVD is not evidence of exploitation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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