---
id: CVE-2026-43068
title: 'ext4: avoid allocate block from corrupted group in ext4_mb_find_by_goal()'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ext4: avoid allocate block from corrupted group in ext4_mb_find_by_goal()

  There's issue as follows:
  ...
  EXT4-fs (mmcblk0p1): Delayed block allocation failed for inode …
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 163a203ddb36c36d4a1c942aececda0cc8d06aa7 <
    fea6b2e250ff48f10d166011b57a8516ae5438c9
  - >-
    Linux >= 163a203ddb36c36d4a1c942aececda0cc8d06aa7 <
    0b84571c886719823d537f05f4f07cad6357c4b7
  - >-
    Linux >= 163a203ddb36c36d4a1c942aececda0cc8d06aa7 <
    ffc0a282462d45fee5957621be5afa29752f3b6d
  - >-
    Linux >= 163a203ddb36c36d4a1c942aececda0cc8d06aa7 <
    2d31a5073f86a177edf44015e0dedb0c47cfd6d8
  - >-
    Linux >= 163a203ddb36c36d4a1c942aececda0cc8d06aa7 <
    9370207b36d26e45a8c8ef0500706d37036edd6b
  - >-
    Linux >= 163a203ddb36c36d4a1c942aececda0cc8d06aa7 <
    1895f7904be71c48f1e6f338b28f24dabd6b8aeb
  - >-
    Linux >= 163a203ddb36c36d4a1c942aececda0cc8d06aa7 <
    1c0d7c4cde38a887c6d74e0c89ddb25226943c78
  - >-
    Linux >= 163a203ddb36c36d4a1c942aececda0cc8d06aa7 <
    46066e3a06647c5b186cc6334409722622d05c44
  - Linux 3.12
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-06T15:27:50.996152Z'
published: '2026-05-05'
updated: '2026-11-06'
sourceUpdated: '2026-11-06T15:32:29.789Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-43068'
references:
  - url: 'https://git.kernel.org/stable/c/fea6b2e250ff48f10d166011b57a8516ae5438c9'
  - url: 'https://git.kernel.org/stable/c/0b84571c886719823d537f05f4f07cad6357c4b7'
  - url: 'https://git.kernel.org/stable/c/ffc0a282462d45fee5957621be5afa29752f3b6d'
  - url: 'https://git.kernel.org/stable/c/2d31a5073f86a177edf44015e0dedb0c47cfd6d8'
  - url: 'https://git.kernel.org/stable/c/9370207b36d26e45a8c8ef0500706d37036edd6b'
  - url: 'https://git.kernel.org/stable/c/1895f7904be71c48f1e6f338b28f24dabd6b8aeb'
  - url: 'https://git.kernel.org/stable/c/1c0d7c4cde38a887c6d74e0c89ddb25226943c78'
  - url: 'https://git.kernel.org/stable/c/46066e3a06647c5b186cc6334409722622d05c44'
tags:
  - cve.org
epss: 0.00117
epssPercentile: 0.01651
ingestedAt: '2026-11-06T15:54:04.026Z'
---

## Overview

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

ext4: avoid allocate block from corrupted group in ext4_mb_find_by_goal()

There's issue as follows:
...
EXT4-fs (mmcblk0p1): Delayed block allocation failed for inode 206 at logical offset 0 with max blocks 1 with error 117
EXT4-fs (mmcblk0p1): This should not happen!! Data will be lost

EXT4-fs (mmcblk0p1): Delayed block allocation failed for inode 206 at logical offset 0 with max blocks 1 with error 117
EXT4-fs (mmcblk0p1): This should not happen!! Data will be lost

EXT4-fs (mmcblk0p1): Delayed block allocation failed for inode 206 at logical offset 0 with max blocks 1 with error 117
EXT4-fs (mmcblk0p1): This should not happen!! Data will be lost

EXT4-fs (mmcblk0p1): Delayed block allocation failed for inode 206 at logical offset 0 with max blocks 1 with error 117
EXT4-fs (mmcblk0p1): This should not happen!! Data will be lost

EXT4-fs (mmcblk0p1): Delayed block allocation failed for inode 2243 at logical offset 0 with max blocks 1 with error 117
EXT4-fs (mmcblk0p1): This should not happen!! Data will be lost

EXT4-fs (mmcblk0p1): Delayed block allocation failed for inode 2239 at logical offset 0 with max blocks 1 with error 117
EXT4-fs (mmcblk0p1): This should not happen!! Data will be lost

EXT4-fs (mmcblk0p1): error count since last fsck: 1
EXT4-fs (mmcblk0p1): initial error at time 1765597433: ext4_mb_generate_buddy:760
EXT4-fs (mmcblk0p1): last error at time 1765597433: ext4_mb_generate_buddy:760
...

According to the log analysis, blocks are always requested from the
corrupted block group. This may happen as follows:
ext4_mb_find_by_goal
  ext4_mb_load_buddy
   ext4_mb_load_buddy_gfp
     ext4_mb_init_cache
      ext4_read_block_bitmap_nowait
      ext4_wait_block_bitmap
       ext4_validate_block_bitmap
        if (!grp || EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
         return -EFSCORRUPTED; // There's no logs.
 if (err)
  return err;  // Will return error
ext4_lock_group(ac->ac_sb, group);
  if (unlikely(EXT4_MB_GRP_BBITMAP_CORRUPT(e4b->bd_info))) // Unreachable
   goto out;

After commit 9008a58e5dce ("ext4: make the bitmap read routines return
real error codes") merged, Commit 163a203ddb36 ("ext4: mark block group
as corrupt on block bitmap error") is no real solution for allocating
blocks from corrupted block groups. This is because if
'EXT4_MB_GRP_BBITMAP_CORRUPT(e4b->bd_info)' is true, then
'ext4_mb_load_buddy()' may return an error. This means that the block
allocation will fail.
Therefore, check block group if corrupted when ext4_mb_load_buddy()
returns error.

## Affected

- `Linux >= 163a203ddb36c36d4a1c942aececda0cc8d06aa7 < fea6b2e250ff48f10d166011b57a8516ae5438c9`
- `Linux >= 163a203ddb36c36d4a1c942aececda0cc8d06aa7 < 0b84571c886719823d537f05f4f07cad6357c4b7`
- `Linux >= 163a203ddb36c36d4a1c942aececda0cc8d06aa7 < ffc0a282462d45fee5957621be5afa29752f3b6d`
- `Linux >= 163a203ddb36c36d4a1c942aececda0cc8d06aa7 < 2d31a5073f86a177edf44015e0dedb0c47cfd6d8`
- `Linux >= 163a203ddb36c36d4a1c942aececda0cc8d06aa7 < 9370207b36d26e45a8c8ef0500706d37036edd6b`
- `Linux >= 163a203ddb36c36d4a1c942aececda0cc8d06aa7 < 1895f7904be71c48f1e6f338b28f24dabd6b8aeb`
- `Linux >= 163a203ddb36c36d4a1c942aececda0cc8d06aa7 < 1c0d7c4cde38a887c6d74e0c89ddb25226943c78`
- `Linux >= 163a203ddb36c36d4a1c942aececda0cc8d06aa7 < 46066e3a06647c5b186cc6334409722622d05c44`
- `Linux 3.12`

## Remediation

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