---
id: CVE-2026-98984
title: 'dcache: don''t put a mountpoint on a dentry that''s being removed'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  dcache: don't put a mountpoint on a dentry that's being removed

  rmdir(), unlink() and rename() call dont_mount() on the victim and then
  detach_mounts() with the victim…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1064f874abc0d05eeed8993815f584d847b72486 <
    5e6bfd9f249f2c74bb63c0f06ad959da3bee0971
  - >-
    Linux >= 1064f874abc0d05eeed8993815f584d847b72486 <
    793cb67b0f52d00c67bd0e76bc57455b5c70ebb8
  - >-
    Linux >= 1064f874abc0d05eeed8993815f584d847b72486 <
    390ddcea2a8aca411b931a8e2863a80ccca8d2b3
  - >-
    Linux >= 1064f874abc0d05eeed8993815f584d847b72486 <
    30a1625022411a387cce9239408ece9955bc9c58
  - >-
    Linux >= 1064f874abc0d05eeed8993815f584d847b72486 <
    75f4197f1e11d2eb75c2d6f916a7d4764db621e5
  - Linux 5e6ef5ef6eaf690faad3a7c6c665ebf45d7b6ccf
  - Linux 839d42687dfce0ed0ea2c6bd8d707cc0e276fbe7
  - Linux 808e83e5add13152bd4a88346487de68395c136b
  - Linux 6de9d08a9718ee9c12ba6343c50141c2d633e3dc
  - Linux >= 4.1.40 < 4.2
  - Linux >= 4.4.54 < 4.5
  - Linux >= 4.9.15 < 4.10
  - Linux >= 4.10.3 < 4.11
  - Linux 4.11
published: '2026-10-23'
updated: '2026-10-23'
sourceUpdated: '2026-10-23T12:20:02.285Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-98984'
references:
  - url: 'https://git.kernel.org/stable/c/5e6bfd9f249f2c74bb63c0f06ad959da3bee0971'
  - url: 'https://git.kernel.org/stable/c/793cb67b0f52d00c67bd0e76bc57455b5c70ebb8'
  - url: 'https://git.kernel.org/stable/c/390ddcea2a8aca411b931a8e2863a80ccca8d2b3'
  - url: 'https://git.kernel.org/stable/c/30a1625022411a387cce9239408ece9955bc9c58'
  - url: 'https://git.kernel.org/stable/c/75f4197f1e11d2eb75c2d6f916a7d4764db621e5'
tags:
  - cve.org
ingestedAt: '2026-10-23T13:24:55.548Z'
---

## Overview

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

dcache: don't put a mountpoint on a dentry that's being removed

rmdir(), unlink() and rename() call dont_mount() on the victim and then
detach_mounts() with the victim's inode locked. do_lock_mount() takes
the inode lock of the mountpoint and checks cant_mount() so a mount
can't show up after detach_mounts().

But attach_recursive_mnt() makes a second mountpoint for the root of the
source mount so that the mounts already located at the destination can
be put on top of it. No inode is locked for that one and d_set_mounted()
only refuses a dentry that is unlinked. Between detach_mounts() and
d_delete() the victim is still hashed:

  rmrace: b passed dont_mount() and detach_mounts(), sleeping
  T2: move_mount(S, /tmp/plcant/x, BENEATH) = 0 errno 0 ()
  T1: rmdir(/tmp/plcant/d/b) = 0 errno 0
      109 107 0:61 /d/b//deleted /tmp/plcant/x rw,relatime - tmpfs tmpfs rw
      108 109 0:63 / /tmp/plcant/x rw,relatime - tmpfs T rw

A bind mount of the directory that's being removed is moved beneath an
existing mount while the rmdir() is located between the two calls. The
mount ends up on the removed directory and nothing will ever detach it.

Check cant_mount() in d_set_mounted() as well. dont_mount() raises the
flag under d_lock before detach_mounts() runs so either the mountpoint
is set first and detach_mounts() finds the mount or the flag is seen and
the mount is refused.

## Affected

- `Linux >= 1064f874abc0d05eeed8993815f584d847b72486 < 5e6bfd9f249f2c74bb63c0f06ad959da3bee0971`
- `Linux >= 1064f874abc0d05eeed8993815f584d847b72486 < 793cb67b0f52d00c67bd0e76bc57455b5c70ebb8`
- `Linux >= 1064f874abc0d05eeed8993815f584d847b72486 < 390ddcea2a8aca411b931a8e2863a80ccca8d2b3`
- `Linux >= 1064f874abc0d05eeed8993815f584d847b72486 < 30a1625022411a387cce9239408ece9955bc9c58`
- `Linux >= 1064f874abc0d05eeed8993815f584d847b72486 < 75f4197f1e11d2eb75c2d6f916a7d4764db621e5`
- `Linux 5e6ef5ef6eaf690faad3a7c6c665ebf45d7b6ccf`
- `Linux 839d42687dfce0ed0ea2c6bd8d707cc0e276fbe7`
- `Linux 808e83e5add13152bd4a88346487de68395c136b`
- `Linux 6de9d08a9718ee9c12ba6343c50141c2d633e3dc`
- `Linux >= 4.1.40 < 4.2`
- `Linux >= 4.4.54 < 4.5`
- `Linux >= 4.9.15 < 4.10`
- `Linux >= 4.10.3 < 4.11`
- `Linux 4.11`

## Remediation

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