---
cve: "CVE-2026-89836"
severity: "HIGH"
cvss: 7.8
epss: "0.2%"
vendor: "Linux"
kev: false
exploited: false
published: "2026-09-16 11:16:50"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-20T20:06:17+02:00"
---

# CVE-2026-89836

> 7.8 HIGH

## Beschreibung

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

## CVSS-Vektor

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

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Lokal | good |
| AC Komplexität | Gering | bad |
| PR Privilegien | Gering | warn |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- Kernel ≥ 7.2.5

## Referenzen

- <https://git.kernel.org/stable/c/cc34df18da92f68f9b384c3ae95ad64be46cb5ee>
- <https://git.kernel.org/stable/c/0dab71381f1b4d12dc2056f8bd5aaa9d93ce9082>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-89836) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_