---
id: CVE-2026-64326
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  block: skip sync_blockdev() on surprise removal in bdev_mark_dead()

  bdev_mark_dead()'s @surprise == true means the device is already gone.
  The filesystem callback fs_b…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  block: skip sync_blockdev() on surprise removal in bdev_mark_dead()

  bdev_mark_dead()'s @surprise == true means the device is already gone.
  The filesystem callback fs_b…
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'
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 6.6, < 6.6.145'
  - 'linux_kernel >= 6.7, < 6.12.96'
  - 'linux_kernel >= 6.13, < 6.18.39'
  - 'linux_kernel >= 6.19, < 7.1.4'
patched:
  - linux_kernel 7.1.4
published: '2026-07-25'
updated: '2026-09-04'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-64326'
references:
  - url: 'https://git.kernel.org/stable/c/49f06cff50a4ccf3b7a1a662ceb892b3b21a527a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/9818bcae3c0ca1dde4b9a334125c46676e0a9b29'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/aa4c4a9315764b2b7a7182e72cc5ea87520436b4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/d6998ddd507c81e3829489a6ead23f17f5acb7fe'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f41cf35ee2a1e31374b3f54e7579c55153506e70'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00159
epssPercentile: 0.0429
ingestedAt: '2026-09-05T13:39:56.203Z'
---

## Overview

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

block: skip sync_blockdev() on surprise removal in bdev_mark_dead()

bdev_mark_dead()'s @surprise == true means the device is already gone.
The filesystem callback fs_bdev_mark_dead() honours this and skips
sync_filesystem(), but the bare block device path (no ->mark_dead op)
lost its !surprise guard when the holder ->mark_dead callback was wired
up (see Fixes), and now calls sync_blockdev() unconditionally, which can
hang forever waiting on writeback that can no longer complete.

syzkaller hit this via nvme_reset_work()'s "I/O queues lost" path:
nvme_mark_namespaces_dead() -> blk_mark_disk_dead() ->
bdev_mark_dead(bdev, true) -> sync_blockdev() blocks in
folio_wait_writeback(), wedging the reset worker and every task waiting
on it.

Skip the sync on surprise removal, matching fs_bdev_mark_dead();
invalidate_bdev() still runs. Orderly removal (surprise == false) is
unchanged.

Found by FuzzNvme(Syzkaller with FEMU fuzzing framework).

## Affected

- `linux_kernel >= 6.6, < 6.6.145`
- `linux_kernel >= 6.7, < 6.12.96`
- `linux_kernel >= 6.13, < 6.18.39`
- `linux_kernel >= 6.19, < 7.1.4`

## Remediation

Upgrade past the affected range:

- `linux_kernel 7.1.4`