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Fencer Vulns
high 8.1

CVE-2026-90301 json

ocfs2: o2hb: quiesce negotiate handlers and timeout work

published 2026-09-17 52 d ago modified 2026-10-30 10 d ago also EUVD-2026-81894

cvss
8.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 48%
public exploits
0
none known

Summary

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().

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

Patch / fix

  • Linux Linux 6.1.191, 6.6.160, 6.12.114, 6.18.57, 7.2.6, 7.3
  • linux Debian 13 6.12.115-2
  • linux Debian 14 7.2.6-1

debian advisories DEBIAN-CVE-2026-90301

  • linux Ubuntu 26.04 LTS 7.0.0-42.42
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1016.17
  • linux-gcp Ubuntu 26.04 LTS 7.0.0-1016.18
  • linux-ibm Ubuntu 26.04 LTS 7.0.0-1017.17
  • linux-riscv Ubuntu 26.04 LTS 7.0.0-42.42.1
  • linux-oracle Ubuntu 26.04 LTS 7.0.0-1015.16
  • linux-hwe-7.0 Ubuntu 24.04 LTS 7.0.0-42.42~24.04.1
  • linux-oem-7.0 Ubuntu 26.04 LTS 7.0.0-1017.17

ubuntu advisories UBUNTU-CVE-2026-90301

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel-source openSUSE Tumbleweed 7.2.7-1.1

opensuse advisories openSUSE-SU-2026:11880-1

  • kernel Azure Linux 3.0 6.6.161.1-1

azure linux advisories AZL-102569

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-90301 updated cvss 5.5

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

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9
    +1 more products
    Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.59% chance of exploitation in the next 30 days, higher than 48% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 8.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

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