---
id: CVE-2026-72472
title: 'nfs: use nfsi->rwsem to protect traversal of the file lock list'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  nfs: use nfsi->rwsem to protect traversal of the file lock list

  Lingfeng identified a bug and suggested two solutions, but both appear
  to have issues.

  Generally, we c…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= c69899a17ca4836230720e65493942d9582a0424 <
    1cda95bf2e9c0e6b63545b7565fe4a1e474322f4
  - >-
    Linux >= c69899a17ca4836230720e65493942d9582a0424 <
    f161ef7b0dd2f51fdb002ba4a4e9bf0ee7409218
  - >-
    Linux >= c69899a17ca4836230720e65493942d9582a0424 <
    e68035178e65e2b3aa386ce61202ff33724ae418
  - >-
    Linux >= c69899a17ca4836230720e65493942d9582a0424 <
    4837fb36219e6c08b666bc31a86841bad8526358
  - Linux 4.0
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-10-16T18:50:31.105592Z'
published: '2026-08-15'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T18:55:25.590Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-72472'
references:
  - url: 'https://git.kernel.org/stable/c/1cda95bf2e9c0e6b63545b7565fe4a1e474322f4'
  - url: 'https://git.kernel.org/stable/c/f161ef7b0dd2f51fdb002ba4a4e9bf0ee7409218'
  - url: 'https://git.kernel.org/stable/c/e68035178e65e2b3aa386ce61202ff33724ae418'
  - url: 'https://git.kernel.org/stable/c/4837fb36219e6c08b666bc31a86841bad8526358'
tags:
  - cve.org
epss: 0.00652
epssPercentile: 0.50216
ingestedAt: '2026-10-16T19:46:24.392Z'
---

## Overview

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

nfs: use nfsi->rwsem to protect traversal of the file lock list

Lingfeng identified a bug and suggested two solutions, but both appear
to have issues.

Generally, we cannot release flc_lock while iterating over the file lock
list to avoid use-after-free (UAF) problems with file locks. However,
functions like nfs_delegation_claim_locks and nfs4_reclaim_locks cannot
adhere to this rule because recover_lock or nfs4_lock_delegation_recall
may take a long time. To resolve this, NFS switches to using nfsi->rwsem
for the same protection, and nfs_reclaim_locks follows this approach.
Although nfs_delegation_claim_locks uses so_delegreturn_mutex instead,
this is inadequate since a single inode can have multiple nfs4_state
instances. Therefore, the fix is to also use nfsi->rwsem in this case.

Furthermore, after commit c69899a17ca4 ("NFSv4: Update of VFS byte range
lock must be atomic with the stateid update"), the functions
nfs4_locku_done and nfs4_lock_done also break this rule because they
call locks_lock_inode_wait without holding nfsi->rwsem. Simply adding
this protection could cause many deadlocks, so instead, the call to
locks_lock_inode_wait is moved into _nfs4_proc_setlk. Regarding the bug
fixed by commit c69899a17ca4 ("NFSv4: Update of VFS byte range
lock must be atomic with the stateid update"), it has been resolved
after commit 0460253913e5 ("NFSv4: nfs4_do_open() is incorrectly triggering
state recovery") because all slots are drained before calling
nfs4_do_reclaim, which prevents concurrent stateid changes along this path.
Also, nfs_delegation_claim_locks does not cause this concurrency either
since when _nfs4_proc_setlk is called with NFS_DELEGATED_STATE, no RPC is
sent, so nfs4_lock_done is not called. Therefore,
nfs4_lock_delegation_recall from nfs_delegation_claim_locks is the first
time the stateid is set.

## Affected

- `Linux >= c69899a17ca4836230720e65493942d9582a0424 < 1cda95bf2e9c0e6b63545b7565fe4a1e474322f4`
- `Linux >= c69899a17ca4836230720e65493942d9582a0424 < f161ef7b0dd2f51fdb002ba4a4e9bf0ee7409218`
- `Linux >= c69899a17ca4836230720e65493942d9582a0424 < e68035178e65e2b3aa386ce61202ff33724ae418`
- `Linux >= c69899a17ca4836230720e65493942d9582a0424 < 4837fb36219e6c08b666bc31a86841bad8526358`
- `Linux 4.0`

## Remediation

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