---
id: CVE-2026-72196
title: 'fs/ntfs3: bound copy_lcns dp->page_lcns[] index in analysis pass'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  fs/ntfs3: bound copy_lcns dp->page_lcns[] index in analysis pass

  In log_replay()'s analysis pass, after find_dp() returns a
  valid DIR_PAGE_ENTRY for the (target_attr, …
severity: high
cvss: 8.4
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 <
    9b3d8cc9d54fcded4de51b2b1026ae7182512077
  - >-
    Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 <
    9b7c28d8c61bdb041936222a09a708531a1c2921
  - >-
    Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 <
    0f13e823bf86bd1800168ea0bb5bca8b8500a81c
  - >-
    Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 <
    d240cd98f5f7b65c90f6b2b6abe3232ccdc405ab
  - >-
    Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 <
    49c86dae0c0ccb8d98ddcdc46987259389c816dd
  - >-
    Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 <
    5e7b598660cfa8e5af172cf4c65cffc126333307
  - Linux 5.15
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T18:43:43.786684Z'
published: '2026-08-15'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T18:45:01.462Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-72196'
references:
  - url: 'https://git.kernel.org/stable/c/9b3d8cc9d54fcded4de51b2b1026ae7182512077'
  - url: 'https://git.kernel.org/stable/c/9b7c28d8c61bdb041936222a09a708531a1c2921'
  - url: 'https://git.kernel.org/stable/c/0f13e823bf86bd1800168ea0bb5bca8b8500a81c'
  - url: 'https://git.kernel.org/stable/c/d240cd98f5f7b65c90f6b2b6abe3232ccdc405ab'
  - url: 'https://git.kernel.org/stable/c/49c86dae0c0ccb8d98ddcdc46987259389c816dd'
  - url: 'https://git.kernel.org/stable/c/5e7b598660cfa8e5af172cf4c65cffc126333307'
tags:
  - cve.org
epss: 0.00185
epssPercentile: 0.07564
ingestedAt: '2026-10-16T19:46:24.422Z'
---

## Overview

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

fs/ntfs3: bound copy_lcns dp->page_lcns[] index in analysis pass

In log_replay()'s analysis pass, after find_dp() returns a
valid DIR_PAGE_ENTRY for the (target_attr, target_vcn) tuple,
the copy_lcns block walks lrh->lcns_follow further entries:

	t16 = le16_to_cpu(lrh->lcns_follow);
	for (i = 0; i < t16; i++) {
	    size_t j = (size_t)(le64_to_cpu(lrh->target_vcn) -
	                        le64_to_cpu(dp->vcn));
	    dp->page_lcns[j + i] = lrh->page_lcns[i];
	}

find_dp() only validates that target_vcn falls within
[dp->vcn, dp->vcn + dp->lcns_follow), i.e., that the FIRST
cluster is covered.  The walk through the further entries is
not bounded against dp->lcns_follow.  For a malformed LRH
where target_vcn = dp->vcn + dp->lcns_follow - 1 and
lrh->lcns_follow > 1, the i > 0 writes overflow the dp's
allocated page_lcns[] array.

Add the missing j + lrh->lcns_follow <= dp->lcns_follow guard.

Reproduced under UML+KASAN on mainline 8d90b09e6741 as a
slab-out-of-bounds write of size 8 from log_replay+0x68d4 on
the mount path.

This is distinct from Pavitra Jha's 2026-05-02 patch
("fs/ntfs3: validate lcns_follow in log_replay conversion",
<20260502154252.164586-1-jhapavitra98@gmail.com>) which
addresses the separate version-0 dirty-page-table conversion
path's memmove(&dp->vcn, ...) call.  The two fixes are
complementary; both should land.

[almaz.alexandrovich@paragon-software.com: clang-formatted the changes,
fixed conflicts]

## Affected

- `Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 < 9b3d8cc9d54fcded4de51b2b1026ae7182512077`
- `Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 < 9b7c28d8c61bdb041936222a09a708531a1c2921`
- `Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 < 0f13e823bf86bd1800168ea0bb5bca8b8500a81c`
- `Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 < d240cd98f5f7b65c90f6b2b6abe3232ccdc405ab`
- `Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 < 49c86dae0c0ccb8d98ddcdc46987259389c816dd`
- `Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 < 5e7b598660cfa8e5af172cf4c65cffc126333307`
- `Linux 5.15`

## Remediation

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