---
id: CVE-2025-21999
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  proc: fix UAF in proc_get_inode()

  Fix race between rmmod and /proc/XXX's inode instantiation.

  The bug is that pde->proc_ops don't belong to /proc, it belongs to a
  mod…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  proc: fix UAF in proc_get_inode()

  Fix race between rmmod and /proc/XXX's inode instantiation.

  The bug is that pde->proc_ops don't belong to /proc, it belongs to a
  mod…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-416
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 2.6.23, < 6.1.132'
  - 'linux_kernel >= 6.2, < 6.6.85'
  - 'linux_kernel >= 6.7, < 6.12.21'
  - 'linux_kernel >= 6.13, < 6.13.9'
  - linux_kernel = 6.14
patched:
  - linux_kernel 6.13.9
published: '2025-04-03'
updated: '2026-07-14'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-21999'
references:
  - url: 'https://git.kernel.org/stable/c/4b0b8445b6fd41e6f62ac90547a0ea9d348de3fa'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/63b53198aff2e4e6c5866a4ff73c7891f958ffa4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/64dc7c68e040251d9ec6e989acb69f8f6ae4a10b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/654b33ada4ab5e926cd9c570196fefa7bec7c1df'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/966f331403dc3ed04ff64eaf3930cf1267965e53'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/eda279586e571b05dff44d48e05f8977ad05855d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ede3e8ac90ae106f0b29cd759aadebc1568f1308'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-019113.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.00228
epssPercentile: 0.13839
ingestedAt: '2026-07-14T13:36:56.146Z'
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2025-04-03T15:26:31.372538Z'
---

## Overview

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

proc: fix UAF in proc_get_inode()

Fix race between rmmod and /proc/XXX's inode instantiation.

The bug is that pde->proc_ops don't belong to /proc, it belongs to a
module, therefore dereferencing it after /proc entry has been registered
is a bug unless use_pde/unuse_pde() pair has been used.

use_pde/unuse_pde can be avoided (2 atomic ops!) because pde->proc_ops
never changes so information necessary for inode instantiation can be
saved _before_ proc_register() in PDE itself and used later, avoiding
pde->proc_ops->...  dereference.

      rmmod                         lookup
sys_delete_module
                         proc_lookup_de
			   pde_get(de);
			   proc_get_inode(dir->i_sb, de);
  mod->exit()
    proc_remove
      remove_proc_subtree
       proc_entry_rundown(de);
  free_module(mod);

                               if (S_ISREG(inode->i_mode))
	                         if (de->proc_ops->proc_read_iter)
                           --> As module is already freed, will trigger UAF

BUG: unable to handle page fault for address: fffffbfff80a702b
PGD 817fc4067 P4D 817fc4067 PUD 817fc0067 PMD 102ef4067 PTE 0
Oops: Oops: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 26 UID: 0 PID: 2667 Comm: ls Tainted: G
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
RIP: 0010:proc_get_inode+0x302/0x6e0
RSP: 0018:ffff88811c837998 EFLAGS: 00010a06
RAX: dffffc0000000000 RBX: ffffffffc0538140 RCX: 0000000000000007
RDX: 1ffffffff80a702b RSI: 0000000000000001 RDI: ffffffffc0538158
RBP: ffff8881299a6000 R08: 0000000067bbe1e5 R09: 1ffff11023906f20
R10: ffffffffb560ca07 R11: ffffffffb2b43a58 R12: ffff888105bb78f0
R13: ffff888100518048 R14: ffff8881299a6004 R15: 0000000000000001
FS:  00007f95b9686840(0000) GS:ffff8883af100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffbfff80a702b CR3: 0000000117dd2000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 proc_lookup_de+0x11f/0x2e0
 __lookup_slow+0x188/0x350
 walk_component+0x2ab/0x4f0
 path_lookupat+0x120/0x660
 filename_lookup+0x1ce/0x560
 vfs_statx+0xac/0x150
 __do_sys_newstat+0x96/0x110
 do_syscall_64+0x5f/0x170
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

[adobriyan@gmail.com: don't do 2 atomic ops on the common path]

## Affected

- `linux_kernel >= 2.6.23, < 6.1.132`
- `linux_kernel >= 6.2, < 6.6.85`
- `linux_kernel >= 6.7, < 6.12.21`
- `linux_kernel >= 6.13, < 6.13.9`
- `linux_kernel = 6.14`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.13.9`