---
id: CVE-2024-47736
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  erofs: handle overlapped pclusters out of crafted images properly

  syzbot reported a task hang issue due to a deadlock case where it is
  waiting for the folio lock of a …
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  erofs: handle overlapped pclusters out of crafted images properly

  syzbot reported a task hang issue due to a deadlock case where it is
  waiting for the folio lock of a …
severity: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-667
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 5.13, < 6.10.13'
  - 'linux_kernel >= 6.11, < 6.11.2'
patched:
  - linux_kernel 6.11.2
published: '2024-10-21'
updated: '2026-07-14'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2024-47736'
references:
  - url: 'https://git.kernel.org/stable/c/1bf7e414cac303c9aec1be67872e19be8b64980c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/9cfa199bcbbbba31cbf97b2786f44f4464f3f29a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/9e2f9d34dd12e6e5b244ec488bcebd0c2d566c50'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b9b30af0e86ffb485301ecd83b9129c9dfb7ebf8'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/c1172e65aad4b115392ea4c6e61e56e5b9b69df4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-019113.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-082556.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.00182
epssPercentile: 0.08021
ingestedAt: '2026-07-14T13:36:54.558Z'
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2024-10-21T12:59:50.164921Z'
---

## Overview

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

erofs: handle overlapped pclusters out of crafted images properly

syzbot reported a task hang issue due to a deadlock case where it is
waiting for the folio lock of a cached folio that will be used for
cache I/Os.

After looking into the crafted fuzzed image, I found it's formed with
several overlapped big pclusters as below:

 Ext:   logical offset   |  length :     physical offset    |  length
   0:        0..   16384 |   16384 :     151552..    167936 |   16384
   1:    16384..   32768 |   16384 :     155648..    172032 |   16384
   2:    32768..   49152 |   16384 :  537223168.. 537239552 |   16384
...

Here, extent 0/1 are physically overlapped although it's entirely
_impossible_ for normal filesystem images generated by mkfs.

First, managed folios containing compressed data will be marked as
up-to-date and then unlocked immediately (unlike in-place folios) when
compressed I/Os are complete.  If physical blocks are not submitted in
the incremental order, there should be separate BIOs to avoid dependency
issues.  However, the current code mis-arranges z_erofs_fill_bio_vec()
and BIO submission which causes unexpected BIO waits.

Second, managed folios will be connected to their own pclusters for
efficient inter-queries.  However, this is somewhat hard to implement
easily if overlapped big pclusters exist.  Again, these only appear in
fuzzed images so let's simply fall back to temporary short-lived pages
for correctness.

Additionally, it justifies that referenced managed folios cannot be
truncated for now and reverts part of commit 2080ca1ed3e4 ("erofs: tidy
up `struct z_erofs_bvec`") for simplicity although it shouldn't be any
difference.

## Affected

- `linux_kernel >= 5.13, < 6.10.13`
- `linux_kernel >= 6.11, < 6.11.2`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.11.2`