---
id: CVE-2024-49884
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ext4: fix slab-use-after-free in ext4_split_extent_at()

  We hit the following use-after-free:

  ==================================================================
  BUG: K…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ext4: fix slab-use-after-free in ext4_split_extent_at()

  We hit the following use-after-free:

  ==================================================================
  BUG: K…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-416
vendor: debian
product: debian_linux
affected:
  - debian_linux = 11.0
  - 'linux_kernel >= 3.18, < 4.19.323'
  - 'linux_kernel >= 4.20, < 5.4.290'
  - 'linux_kernel >= 5.5, < 5.10.227'
  - 'linux_kernel >= 5.11, < 5.15.168'
  - 'linux_kernel >= 5.16, < 6.1.113'
  - 'linux_kernel >= 6.2, < 6.6.55'
  - 'linux_kernel >= 6.7, < 6.10.14'
  - 'linux_kernel >= 6.11, < 6.11.3'
patched:
  - linux_kernel 6.11.3
published: '2024-10-21'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T01:18:59.270'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2024-49884'
references:
  - url: 'https://git.kernel.org/stable/c/393a46f60ea4f249dc9d496d4eb2d542f5e11ade'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/448100a29395b0c8b4c42967155849fe0fbe808f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/5d949ea75bb529ea6342e83465938a3b0ac51238'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/8fe117790b37c84c651e2bad9efc0e7fda73c0e3'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/915ac3630488af0ca194dc63b86d99802b4f6e18'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a5401d4c3e2a3d25643c567d26e6de327774a2c9'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/c26ab35702f8cd0cdc78f96aa5856bfb77be798f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/cafcc1bd62934547c76abf46c6d0d54f135006fe'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e52f933598b781d291b9297e39c463536da0e185'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-355557.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-398330.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.00268
epssPercentile: 0.1758
ingestedAt: '2026-10-15T03:30:12.751Z'
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2024-10-22T13:45:15.776351Z'
---

## Overview

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

ext4: fix slab-use-after-free in ext4_split_extent_at()

We hit the following use-after-free:

==================================================================
BUG: KASAN: slab-use-after-free in ext4_split_extent_at+0xba8/0xcc0
Read of size 2 at addr ffff88810548ed08 by task kworker/u20:0/40
CPU: 0 PID: 40 Comm: kworker/u20:0 Not tainted 6.9.0-dirty #724
Call Trace:
 <TASK>
 kasan_report+0x93/0xc0
 ext4_split_extent_at+0xba8/0xcc0
 ext4_split_extent.isra.0+0x18f/0x500
 ext4_split_convert_extents+0x275/0x750
 ext4_ext_handle_unwritten_extents+0x73e/0x1580
 ext4_ext_map_blocks+0xe20/0x2dc0
 ext4_map_blocks+0x724/0x1700
 ext4_do_writepages+0x12d6/0x2a70
[...]

Allocated by task 40:
 __kmalloc_noprof+0x1ac/0x480
 ext4_find_extent+0xf3b/0x1e70
 ext4_ext_map_blocks+0x188/0x2dc0
 ext4_map_blocks+0x724/0x1700
 ext4_do_writepages+0x12d6/0x2a70
[...]

Freed by task 40:
 kfree+0xf1/0x2b0
 ext4_find_extent+0xa71/0x1e70
 ext4_ext_insert_extent+0xa22/0x3260
 ext4_split_extent_at+0x3ef/0xcc0
 ext4_split_extent.isra.0+0x18f/0x500
 ext4_split_convert_extents+0x275/0x750
 ext4_ext_handle_unwritten_extents+0x73e/0x1580
 ext4_ext_map_blocks+0xe20/0x2dc0
 ext4_map_blocks+0x724/0x1700
 ext4_do_writepages+0x12d6/0x2a70
[...]
==================================================================

The flow of issue triggering is as follows:

ext4_split_extent_at
  path = *ppath
  ext4_ext_insert_extent(ppath)
    ext4_ext_create_new_leaf(ppath)
      ext4_find_extent(orig_path)
        path = *orig_path
        read_extent_tree_block
          // return -ENOMEM or -EIO
        ext4_free_ext_path(path)
          kfree(path)
        *orig_path = NULL
  a. If err is -ENOMEM:
  ext4_ext_dirty(path + path->p_depth)
  // path use-after-free !!!
  b. If err is -EIO and we have EXT_DEBUG defined:
  ext4_ext_show_leaf(path)
    eh = path[depth].p_hdr
    // path also use-after-free !!!

So when trying to zeroout or fix the extent length, call ext4_find_extent()
to update the path.

In addition we use *ppath directly as an ext4_ext_show_leaf() input to
avoid possible use-after-free when EXT_DEBUG is defined, and to avoid
unnecessary path updates.

## Affected

- `debian_linux = 11.0`
- `linux_kernel >= 3.18, < 4.19.323`
- `linux_kernel >= 4.20, < 5.4.290`
- `linux_kernel >= 5.5, < 5.10.227`
- `linux_kernel >= 5.11, < 5.15.168`
- `linux_kernel >= 5.16, < 6.1.113`
- `linux_kernel >= 6.2, < 6.6.55`
- `linux_kernel >= 6.7, < 6.10.14`
- `linux_kernel >= 6.11, < 6.11.3`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.11.3`