---
id: CVE-2026-98986
title: 'namespace: remove the fsnotify marks of a mount namespace in process context'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  namespace: remove the fsnotify marks of a mount namespace in process context

  mnt_ns_release() drops the last passive reference of a mount namespace
  and removes its fan…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= bf630c40164162ba1d3933c2f5e3397d083e0948 <
    888363d74c3b5d32e2accf217add70f8b38e0e2b
  - >-
    Linux >= bf630c40164162ba1d3933c2f5e3397d083e0948 <
    9e820a6becdd955a04adbedfd767253a47eedd9e
  - >-
    Linux >= bf630c40164162ba1d3933c2f5e3397d083e0948 <
    1a116222acdcc1bc1a8350727ae6f28907d44594
  - Linux 6.15
published: '2026-10-23'
updated: '2026-10-23'
sourceUpdated: '2026-10-23T12:20:04.966Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-98986'
references:
  - url: 'https://git.kernel.org/stable/c/888363d74c3b5d32e2accf217add70f8b38e0e2b'
  - url: 'https://git.kernel.org/stable/c/9e820a6becdd955a04adbedfd767253a47eedd9e'
  - url: 'https://git.kernel.org/stable/c/1a116222acdcc1bc1a8350727ae6f28907d44594'
tags:
  - cve.org
ingestedAt: '2026-10-23T13:24:55.547Z'
---

## Overview

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

namespace: remove the fsnotify marks of a mount namespace in process context

mnt_ns_release() drops the last passive reference of a mount namespace
and removes its fanotify marks via fsnotify_mntns_delete(). That takes
the mutex of every group with a mark on the namespace and the spinlock
of the connector. Fine from process context. But mnt_ns_tree_remove()
hands the reference the namespace was allocated with to call_rcu() and
so the marks are removed from the RCU softirq:

  BUG: sleeping function called from invalid context at kernel/locking/mutex.c:623
  in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 0, name: swapper/3
   __mutex_lock+0x113/0x24b0
   fsnotify_destroy_marks+0x11b/0x3d0
   mnt_ns_release_rcu+0x57/0xa0
   rcu_core+0x6b6/0x1e40

and lockdep complains about the connector lock being taken from softirq
context. A fanotify group with a FAN_MARK_MNTNS mark on the mount
namespace of another task is all that's needed. Root in a user
namespace can do that for a mount namespace it owns. The task exits and
the namespace is freed with the mark still on it.

Remove the marks in free_mnt_ns() before the namespace is handed to RCU.
That runs in process context once the last active reference is gone. A
mark is added through a file descriptor to the namespace which holds an
active reference so no mark can show up after that.

## Affected

- `Linux >= bf630c40164162ba1d3933c2f5e3397d083e0948 < 888363d74c3b5d32e2accf217add70f8b38e0e2b`
- `Linux >= bf630c40164162ba1d3933c2f5e3397d083e0948 < 9e820a6becdd955a04adbedfd767253a47eedd9e`
- `Linux >= bf630c40164162ba1d3933c2f5e3397d083e0948 < 1a116222acdcc1bc1a8350727ae6f28907d44594`
- `Linux 6.15`

## Remediation

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