---
id: CVE-2026-53017
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  f2fs: fix data loss caused by incorrect use of nat_entry flag

  Data loss can occur when fsync is performed on a newly created file
  (before any checkpoint has been writt…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  f2fs: fix data loss caused by incorrect use of nat_entry flag

  Data loss can occur when fsync is performed on a newly created file
  (before any checkpoint has been writt…
severity: none
published: '2026-06-24'
updated: '2026-07-10'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-53017'
references:
  - url: 'https://git.kernel.org/stable/c/20cedb4d9f6b230d0ee469690b8f868f06a07c29'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/238e14eb7226f883b72caccd2d37bf5707df066b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00112
epssPercentile: 0.01562
ingestedAt: '2026-07-11T19:15:11.809Z'
---

## Overview

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

f2fs: fix data loss caused by incorrect use of nat_entry flag

Data loss can occur when fsync is performed on a newly created file
(before any checkpoint has been written) concurrently with a checkpoint
operation. The scenario is as follows:

create & write & fsync 'file A'                 write checkpoint
- f2fs_do_sync_file // inline inode
 - f2fs_write_inode // inode folio is dirty
                                                - f2fs_write_checkpoint
                                                 - f2fs_flush_merged_writes
                                                 - f2fs_sync_node_pages
                                                 - f2fs_flush_nat_entries
 - f2fs_fsync_node_pages // no dirty node
 - f2fs_need_inode_block_update // return false
 SPO and lost 'file A'

f2fs_flush_nat_entries() sets the IS_CHECKPOINTED and HAS_LAST_FSYNC
flags for the nat_entry, but this does not mean that the checkpoint has
actually completed successfully. However, f2fs_need_inode_block_update()
checks these flags and incorrectly assumes that the checkpoint has
finished.

The root cause is that the semantics of IS_CHECKPOINTED and
HAS_LAST_FSYNC are only guaranteed after the checkpoint write fully
completes.

This patch modifies f2fs_need_inode_block_update() to acquire the
sbi->node_write lock before reading the nat_entry flags, ensuring that
once IS_CHECKPOINTED and HAS_LAST_FSYNC are observed to be set, the
checkpoint operation has already completed.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.