Cloudanix VulnDB

CVE-2023-54068

None

CVSS

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EPSS

0.2%

Published

Dec 24, 2025

CISA due date

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Cloudanix analysis

Schedule a fix SSVC: Track

A flaw in the Linux kernel can make computers using a certain type of storage format crash when multiple programs try to save files at the same time.

Exploitation
Local Privilege
Attacker needs
Local User
Complexity
Moderate
Impact
Denial Of Service
Component
OS kernel
Class
Race Condition
Remediation
Patch
Effort
Medium
Patch risk
Low

What it actually does

Race condition in f2fs compression path allows the same page to enter writeback state multiple times under concurrent writers, triggering BUG_ON in folio_end_writeback.

Why it matters to the business

Systems using f2fs with compression enabled can experience kernel crashes during normal concurrent file writes, leading to unplanned downtime and potential data inconsistency on affected Linux deployments.

How an attack unfolds

An attacker with local write access to an f2fs filesystem that has compression enabled triggers concurrent write operations from multiple processes; the missing wait for page writeback in f2fs_write_raw_pages permits a second set_page_writeback on an already-in-flight page, causing the kernel BUG.

How to fix it

Upgrade the Linux kernel to a version containing commit a8226a45b2a9ce83ba7a167a387a00fecc319e71 or later; rebuild and reboot with the patched kernel; disable f2fs compression as a temporary workaround if patching is delayed.

How to confirm the fix worked

Confirm the running kernel contains commit a8226a45b2a9ce83ba7a167a387a00fecc319e71; attempt concurrent writes on a compressed f2fs file and verify absence of BUG at mm/filemap.c:1619; review dmesg for f2fs_write_end_io call traces.

Typical attack path

  1. Mount f2fs volume with compression enabled
  2. Spawn multiple processes performing overlapping writes to the same file
  3. Trigger redirty and subsequent writeback paths without intervening wait
  4. Observe kernel panic from duplicate writeback state

How to detect it

Search kernel logs for 'kernel BUG at mm/filemap.c:1619' combined with f2fs_write_end_io and blk_update_request frames; monitor for repeated page writeback failures on f2fs volumes.

What your security team should do

  • Prioritize kernel update for all systems using f2fs compression within the next maintenance window
  • Add f2fs compression usage to asset inventory and monitoring scope
  • Test the patched kernel in a staging environment with concurrent I/O workloads before broad deployment

The record

In the Linux kernel, the following vulnerability has been resolved: f2fs: compress: fix to call f2fs_wait_on_page_writeback() in f2fs_write_raw_pages() BUG_ON() will be triggered when writing files concurrently, because the same page is writtenback multiple times. 1597 void folio_end_writeback(struct folio *folio) 1598 { ...... 1618 if (!__folio_end_writeback(folio)) 1619 BUG(); ...... 1625 } kernel BUG at mm/filemap.c:1619! Call Trace: <TASK> f2fs_write_end_io+0x1a0/0x370 blk_update_request+0x6c/0x410 blk_mq_end_request+0x15/0x130 blk_complete_reqs+0x3c/0x50 __do_softirq+0xb8/0x29b ? sort_range+0x20/0x20 run_ksoftirqd+0x19/0x20 smpboot_thread_fn+0x10b/0x1d0 kthread+0xde/0x110 ? kthread_complete_and_exit+0x20/0x20 ret_from_fork+0x22/0x30 </TASK> Below is the concurrency scenario: [Process A] [Process B] [Process C] f2fs_write_raw_pages() - redirty_page_for_writepage() - unlock page() f2fs_do_write_data_page() - lock_page() - clear_page_dirty_for_io() - set_page_writeback() [1st writeback] ..... - unlock page() generic_perform_write() - f2fs_write_begin() - wait_for_stable_page() - f2fs_write_end() - set_page_dirty() - lock_page() - f2fs_do_write_data_page() - set_page_writeback() [2st writeback] This problem was introduced by the previous commit 7377e853967b ("f2fs: compress: fix potential deadlock of compress file"). All pagelocks were released in f2fs_write_raw_pages(), but whether the page was in the writeback state was ignored in the subsequent writing process. Let's fix it by waiting for the page to writeback before writing.

Affected packages

Ecosystem Package Introduced Fixed
Linux Kernel 5.6.0 5.10.180

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