---
id: CVE-2026-53064
title: 'dm cache: fix null-deref with concurrent writes in passthrough mode'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  dm cache: fix null-deref with concurrent writes in passthrough mode

  In passthrough mode, when dm-cache starts to invalidate a cache
  entry and bio prison cell lock fail…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= b29d4986d0da1a27cd35917cdb433672f5c95d7f <
    01264a6a3a3ad7ac1d73443299cd5a9568002454
  - >-
    Linux >= b29d4986d0da1a27cd35917cdb433672f5c95d7f <
    ee38fb00e1a80f46a4990e38f25ecb04ae7b7417
  - >-
    Linux >= b29d4986d0da1a27cd35917cdb433672f5c95d7f <
    c7fb6bc864c4910b344dafa36dd5028e9b980768
  - >-
    Linux >= b29d4986d0da1a27cd35917cdb433672f5c95d7f <
    0aa745fea1f8dc81bcdd0a45e215b6706727b482
  - >-
    Linux >= b29d4986d0da1a27cd35917cdb433672f5c95d7f <
    a2635d541a93fd111e743cf14b6275dc81be2abc
  - >-
    Linux >= b29d4986d0da1a27cd35917cdb433672f5c95d7f <
    25dcc1989c194ba2b5fb6d03cbb9b83814ac0d15
  - >-
    Linux >= b29d4986d0da1a27cd35917cdb433672f5c95d7f <
    df3b8ef06cc62de4fca5d2108e285085b3cffd44
  - >-
    Linux >= b29d4986d0da1a27cd35917cdb433672f5c95d7f <
    7d1f98d668ee34c1d15bdc0420fdd062f24a27c0
  - Linux 4.12
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-06T16:17:38.750269Z'
published: '2026-06-24'
updated: '2026-11-06'
sourceUpdated: '2026-11-06T16:23:57.905Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-53064'
references:
  - url: 'https://git.kernel.org/stable/c/01264a6a3a3ad7ac1d73443299cd5a9568002454'
  - url: 'https://git.kernel.org/stable/c/ee38fb00e1a80f46a4990e38f25ecb04ae7b7417'
  - url: 'https://git.kernel.org/stable/c/c7fb6bc864c4910b344dafa36dd5028e9b980768'
  - url: 'https://git.kernel.org/stable/c/0aa745fea1f8dc81bcdd0a45e215b6706727b482'
  - url: 'https://git.kernel.org/stable/c/a2635d541a93fd111e743cf14b6275dc81be2abc'
  - url: 'https://git.kernel.org/stable/c/25dcc1989c194ba2b5fb6d03cbb9b83814ac0d15'
  - url: 'https://git.kernel.org/stable/c/df3b8ef06cc62de4fca5d2108e285085b3cffd44'
  - url: 'https://git.kernel.org/stable/c/7d1f98d668ee34c1d15bdc0420fdd062f24a27c0'
tags:
  - cve.org
epss: 0.00123
epssPercentile: 0.02042
ingestedAt: '2026-11-06T16:57:43.298Z'
---

## Overview

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

dm cache: fix null-deref with concurrent writes in passthrough mode

In passthrough mode, when dm-cache starts to invalidate a cache
entry and bio prison cell lock fails due to concurrent write to
the same cached block, mg->cell remains NULL. The error path in
invalidate_complete() attempts to unlock and free the cell
unconditionally, causing a NULL pointer dereference:

KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 UID: 0 PID: 134 Comm: fio Not tainted 6.19.0-rc7 #3 PREEMPT
RIP: 0010:dm_cell_unlock_v2+0x3f/0x210
<snip>
Call Trace:
 invalidate_complete+0xef/0x430
 map_bio+0x130f/0x1a10
 cache_map+0x320/0x6b0
 __map_bio+0x458/0x510
 dm_submit_bio+0x40e/0x16d0
 __submit_bio+0x419/0x870
<snip>

Reproduce steps:

1. Create a cache device

dmsetup create cmeta --table "0 8192 linear /dev/sdc 0"
dmsetup create cdata --table "0 131072 linear /dev/sdc 8192"
dmsetup create corig --table "0 262144 linear /dev/sdc 262144"
dd if=/dev/zero of=/dev/mapper/cmeta bs=4k count=1 oflag=direct
dmsetup create cache --table "0 262144 cache /dev/mapper/cmeta \
/dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0"

2. Promote the first data block into cache

fio --filename=/dev/mapper/cache --name=populate --rw=write --bs=4k \
--direct=1 --size=64k

3. Reload the cache into passthrough mode

dmsetup suspend cache
dmsetup reload cache --table "0 262144 cache /dev/mapper/cmeta \
/dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 passthrough smq 0"
dmsetup resume cache

4. Write to the first cached block concurrently

fio --filename=/dev/mapper/cache --name test --rw=randwrite --bs=4k \
--randrepeat=0 --direct=1 --numjobs=2 --size 64k

Fix by checking if mg->cell is valid before attempting to unlock it.

## Affected

- `Linux >= b29d4986d0da1a27cd35917cdb433672f5c95d7f < 01264a6a3a3ad7ac1d73443299cd5a9568002454`
- `Linux >= b29d4986d0da1a27cd35917cdb433672f5c95d7f < ee38fb00e1a80f46a4990e38f25ecb04ae7b7417`
- `Linux >= b29d4986d0da1a27cd35917cdb433672f5c95d7f < c7fb6bc864c4910b344dafa36dd5028e9b980768`
- `Linux >= b29d4986d0da1a27cd35917cdb433672f5c95d7f < 0aa745fea1f8dc81bcdd0a45e215b6706727b482`
- `Linux >= b29d4986d0da1a27cd35917cdb433672f5c95d7f < a2635d541a93fd111e743cf14b6275dc81be2abc`
- `Linux >= b29d4986d0da1a27cd35917cdb433672f5c95d7f < 25dcc1989c194ba2b5fb6d03cbb9b83814ac0d15`
- `Linux >= b29d4986d0da1a27cd35917cdb433672f5c95d7f < df3b8ef06cc62de4fca5d2108e285085b3cffd44`
- `Linux >= b29d4986d0da1a27cd35917cdb433672f5c95d7f < 7d1f98d668ee34c1d15bdc0420fdd062f24a27c0`
- `Linux 4.12`

## Remediation

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