---
id: CVE-2026-90277
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  md/md-llbitmap: prevent create failure bitmap UAF

  llbitmap_create() publishes mddev->bitmap before reading the bitmap
  superblock
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  md/md-llbitmap: prevent create failure bitmap UAF

  llbitmap_create() publishes mddev->bitmap before reading the bitmap
  superblock. This is needed because llbitmap_read_…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 5ab829f1971dc99f2aac10846c378e67fc875abc <
    930cc4f1af5a1afcd545a6ba00e38921ff8401e0
  - >-
    Linux >= 5ab829f1971dc99f2aac10846c378e67fc875abc <
    2f0722435ce3a844dbb66b9bb0a18229dcc8739c
  - >-
    Linux >= 5ab829f1971dc99f2aac10846c378e67fc875abc <
    2116c2f0a0e547615886900e2ed8c529c016499b
  - Linux 6.18
published: '2026-09-17'
updated: '2026-09-17'
sourceUpdated: '2026-09-17T17:17:24.353'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-90277'
references:
  - url: 'https://git.kernel.org/stable/c/2116c2f0a0e547615886900e2ed8c529c016499b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/2f0722435ce3a844dbb66b9bb0a18229dcc8739c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/930cc4f1af5a1afcd545a6ba00e38921ff8401e0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-17T16:21:47.836Z'
epss: 0.00206
epssPercentile: 0.09468
---

## Overview

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

md/md-llbitmap: prevent create failure bitmap UAF

llbitmap_create() publishes mddev->bitmap before reading the bitmap
superblock. This is needed because llbitmap_read_sb() can initialize a
new bitmap and flush it through helpers that use mddev->bitmap.

If llbitmap_read_sb() fails, the old cleanup dropped bitmap_info.mutex
and freed llbitmap before clearing mddev->bitmap. Readers such as
/proc/mdstat rely on bitmap_info.mutex to keep the bitmap pointer stable
while collecting bitmap stats, so they could observe the stale pointer
after the failed create path released the mutex.

Clear mddev->bitmap while still holding bitmap_info.mutex, then free the
failed llbitmap after dropping the mutex. This makes mutex-protected
readers see either a live bitmap or no bitmap.

## Remediation

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