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Fencer Vulns
high 7.8

CVE-2026-89836 json

f2fs: fix folio_nr_pages() race after put in large folio invalidate

published 2026-09-16 54 d ago modified 2026-10-19 21 d ago also EUVD-2026-80436

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 5%
public exploits
0
none known

Summary

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

f2fs: fix folio_nr_pages() race after put in large folio invalidate

Our v6.18 based Android system is continuely suffering livelock and bad page stat as shown in[1] which related to broken xarray slot status. By investigating big folio operations within f2fs, we find below races and fix it by get the nr_pages before drop the refcount and folio_lock.

f2fs_get_read_data_folio() calls f2fs_folio_put() before folio_nr_pages() when invalidating a large folio from the page cache. That unlocks the folio and drops the caller reference, leaving a window where a concurrent truncate or folio split can shrink the compound folio or free it before the invalidate range is computed. An undersized range then leaves split sub-folios in mapping->i_pages, which can later interact badly with truncate and reclaim (stale xarray entries and bad page state when folio->mapping no longer matches the mapping being truncated).

[1] PID: 2594 TASK: ffffff8169b81580 CPU: 7 COMMAND: "Thread-3" #0 [ffffffc08ef2b8a0] xas_load at ffffffe52d1f42a4 #1 [ffffffc08ef2b900] find_get_entries at ffffffe52c185798 #2 [ffffffc08ef2bb60] truncate_inode_pages_range at ffffffe52c19e83c #3 [ffffffc08ef2bbc0] truncate_inode_pages_final at ffffffe52c19ec2c #4 [ffffffc08ef2bc20] f2fs_evict_inode at ffffffe52c4c8400 #5 [ffffffc08ef2bcc0] evict at ffffffe52c2de9f4 #6 [ffffffc08ef2bd00] iput at ffffffe52c2db1b4 #7 [ffffffc08ef2bd30] dentry_unlink_inode at ffffffe52c2d7204 #8 [ffffffc08ef2bd50] __dentry_kill at ffffffe52c2d3dcc #9 [ffffffc08ef2bd80] dput at ffffffe52c2d3c3c #10 [ffffffc08ef2bda0] __fput at ffffffe52c2b0a7c #11 [ffffffc08ef2bde0] ____fput at ffffffe52c2b1034 #12 [ffffffc08ef2bdf0] task_work_run at ffffffe52beea200 #13 [ffffffc08ef2be20] exit_to_user_mode_loop at ffffffe52bfbc17c #14 [ffffffc08ef2be80] el0_svc at ffffffe52d1f8e54 #15 [ffffffc08ef2beb0] el0t_64_sync_handler at ffffffe52d1f8d10

Patch / fix

  • Linux Linux 7.2.5, 7.3
  • linux Debian 14 7.2.6-1

debian advisories DEBIAN-CVE-2026-89836

  • 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-2026-89836

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

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-2026-89836 updated cvss 5.5

kernel: f2fs: fix folio_nr_pages() race after put in large folio invalidate

  • 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

0.17% chance of exploitation in the next 30 days, higher than 5% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.