---
id: CVE-2026-93794
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  smb/client: flush dirty data before punching a hole

  Punching a hole after a large buffered write may leave the range
  reported as data
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  smb/client: flush dirty data before punching a hole

  Punching a hole after a large buffered write may leave the range
  reported as data. Reproduce it with:

    xfs_io -f …
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    6c265aca08155e519a8f6f6071c59dff4f535f70
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    39562a56cdb515f6635c3e7bfe6629439b18a169
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    d7d2adcd022baade5cab65ca492ce63421ce3a6e
  - Linux < 6.12.111
  - Linux < 6.18.53
  - Linux (all versions)
published: '2026-09-24'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T13:17:20.000'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-93794'
references:
  - url: 'https://git.kernel.org/stable/c/39562a56cdb515f6635c3e7bfe6629439b18a169'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/6c265aca08155e519a8f6f6071c59dff4f535f70'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/d7d2adcd022baade5cab65ca492ce63421ce3a6e'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-24T16:47:15.901Z'
---

## Overview

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

smb/client: flush dirty data before punching a hole

Punching a hole after a large buffered write may leave the range
reported as data. Reproduce it with:

  xfs_io -f \
    -c "pwrite -b 3m -S 0x61 0 3m" \
    -c "fpunch 1m 1m" \
    -c "seek -h 0" \
    -c "seek -d 1m" \
    /mnt/test/repro

Punching 1 MiB at offset 1 MiB should produce:

  0          1 MiB       2 MiB       3 MiB
  |  DATA    |   HOLE    |   DATA    | EOF

Instead, the entire file is reported as data. SEEK_HOLE(0) returns EOF,
and SEEK_DATA(1M) returns 1M.

This happens because a dirty folio spanning the punched range can be
written back after the punch and refill the hole.

Fix this by flushing and waiting for dirty data in the punched range
before invalidating the page cache and issuing FSCTL_SET_ZERO_DATA.

The xfstests generic/539 pass against Samba/ksmbd with this change.

## Remediation

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