---
id: CVE-2023-53593
title: 'cifs: Release folio lock on fscache read hit.'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  cifs: Release folio lock on fscache read hit.

  Under the current code, when cifs_readpage_worker is called, the call
  contract is that the callee should unlock the page.…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 0174ee9947bd0f24fee2794b35258960d108b7aa <
    9e725386d4262ef23ae51993f04602bc535b5be2
  - >-
    Linux >= 0174ee9947bd0f24fee2794b35258960d108b7aa <
    7a9fb689c1a1dc373887621a3bfa3810df0abde4
  - >-
    Linux >= 0174ee9947bd0f24fee2794b35258960d108b7aa <
    69513dd669e243928f7450893190915a88f84a2b
  - Linux 5.17
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-05T20:24:45.466008Z'
published: '2025-10-04'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T20:31:16.160Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2023-53593'
references:
  - url: 'https://git.kernel.org/stable/c/9e725386d4262ef23ae51993f04602bc535b5be2'
  - url: 'https://git.kernel.org/stable/c/7a9fb689c1a1dc373887621a3bfa3810df0abde4'
  - url: 'https://git.kernel.org/stable/c/69513dd669e243928f7450893190915a88f84a2b'
tags:
  - cve.org
epss: 0.00146
epssPercentile: 0.03898
ingestedAt: '2026-11-05T22:38:31.814Z'
---

## Overview

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

cifs: Release folio lock on fscache read hit.

Under the current code, when cifs_readpage_worker is called, the call
contract is that the callee should unlock the page. This is documented
in the read_folio section of Documentation/filesystems/vfs.rst as:

> The filesystem should unlock the folio once the read has completed,
> whether it was successful or not.

Without this change, when fscache is in use and cache hit occurs during
a read, the page lock is leaked, producing the following stack on
subsequent reads (via mmap) to the page:

$ cat /proc/3890/task/12864/stack
[<0>] folio_wait_bit_common+0x124/0x350
[<0>] filemap_read_folio+0xad/0xf0
[<0>] filemap_fault+0x8b1/0xab0
[<0>] __do_fault+0x39/0x150
[<0>] do_fault+0x25c/0x3e0
[<0>] __handle_mm_fault+0x6ca/0xc70
[<0>] handle_mm_fault+0xe9/0x350
[<0>] do_user_addr_fault+0x225/0x6c0
[<0>] exc_page_fault+0x84/0x1b0
[<0>] asm_exc_page_fault+0x27/0x30

This requires a reboot to resolve; it is a deadlock.

Note however that the call to cifs_readpage_from_fscache does mark the
page clean, but does not free the folio lock. This happens in
__cifs_readpage_from_fscache on success. Releasing the lock at that
point however is not appropriate as cifs_readahead also calls
cifs_readpage_from_fscache and *does* unconditionally release the lock
after its return. This change therefore effectively makes
cifs_readpage_worker work like cifs_readahead.

## Affected

- `Linux >= 0174ee9947bd0f24fee2794b35258960d108b7aa < 9e725386d4262ef23ae51993f04602bc535b5be2`
- `Linux >= 0174ee9947bd0f24fee2794b35258960d108b7aa < 7a9fb689c1a1dc373887621a3bfa3810df0abde4`
- `Linux >= 0174ee9947bd0f24fee2794b35258960d108b7aa < 69513dd669e243928f7450893190915a88f84a2b`
- `Linux 5.17`

## Remediation

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