---
id: CVE-2026-68450
title: 'btrfs: free mapping node on duplicate reloc root insert'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  btrfs: free mapping node on duplicate reloc root insert

  __add_reloc_root() allocates a mapping_node before inserting it into
  rc->reloc_root_tree.  If rb_simple_insert(…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 57a304cfd43b2b4a5b44b8f5dc026abb34183068 <
    29d9746812d8b7c37d594f484e994fd552c3ec33
  - >-
    Linux >= 57a304cfd43b2b4a5b44b8f5dc026abb34183068 <
    b7c5b8e1d5f0779dfbabc3068b7ac0f12e53b3a8
  - >-
    Linux >= 57a304cfd43b2b4a5b44b8f5dc026abb34183068 <
    92bedc0455552b42ada1a1f42b0e3a8593cdfccc
  - >-
    Linux >= 57a304cfd43b2b4a5b44b8f5dc026abb34183068 <
    14a8be9428435ee17f17fae7991215c246b7fd43
  - >-
    Linux >= 57a304cfd43b2b4a5b44b8f5dc026abb34183068 <
    797dc567146c7e3c4f8d9680e4fbc76e0a6d9151
  - >-
    Linux >= 57a304cfd43b2b4a5b44b8f5dc026abb34183068 <
    ae0629ff9ccb836416ada129f4edc7efea6eaaad
  - >-
    Linux >= 57a304cfd43b2b4a5b44b8f5dc026abb34183068 <
    6a8269b6459ed870a8156c106a0f597383907872
  - Linux 5.13
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-06T16:49:44.195694Z'
published: '2026-08-12'
updated: '2026-11-06'
sourceUpdated: '2026-11-06T16:55:17.167Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-68450'
references:
  - url: 'https://git.kernel.org/stable/c/29d9746812d8b7c37d594f484e994fd552c3ec33'
  - url: 'https://git.kernel.org/stable/c/b7c5b8e1d5f0779dfbabc3068b7ac0f12e53b3a8'
  - url: 'https://git.kernel.org/stable/c/92bedc0455552b42ada1a1f42b0e3a8593cdfccc'
  - url: 'https://git.kernel.org/stable/c/14a8be9428435ee17f17fae7991215c246b7fd43'
  - url: 'https://git.kernel.org/stable/c/797dc567146c7e3c4f8d9680e4fbc76e0a6d9151'
  - url: 'https://git.kernel.org/stable/c/ae0629ff9ccb836416ada129f4edc7efea6eaaad'
  - url: 'https://git.kernel.org/stable/c/6a8269b6459ed870a8156c106a0f597383907872'
tags:
  - cve.org
epss: 0.00161
epssPercentile: 0.05342
ingestedAt: '2026-11-06T18:00:12.602Z'
---

## Overview

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

btrfs: free mapping node on duplicate reloc root insert

__add_reloc_root() allocates a mapping_node before inserting it into
rc->reloc_root_tree.  If rb_simple_insert() finds an existing entry, it
returns the existing rb_node and leaves the newly allocated node unlinked.

The error path then returns -EEXIST without freeing the new node.  Since
the node was never inserted into reloc_root_tree, the later cleanup in
put_reloc_control() cannot find it either.

Free the newly allocated node before returning -EEXIST.

The callers currently assert that -EEXIST should not happen, so this is a
defensive cleanup for an unexpected duplicate insert path.  If the path is
ever reached, the local allocation should still be released.

## Affected

- `Linux >= 57a304cfd43b2b4a5b44b8f5dc026abb34183068 < 29d9746812d8b7c37d594f484e994fd552c3ec33`
- `Linux >= 57a304cfd43b2b4a5b44b8f5dc026abb34183068 < b7c5b8e1d5f0779dfbabc3068b7ac0f12e53b3a8`
- `Linux >= 57a304cfd43b2b4a5b44b8f5dc026abb34183068 < 92bedc0455552b42ada1a1f42b0e3a8593cdfccc`
- `Linux >= 57a304cfd43b2b4a5b44b8f5dc026abb34183068 < 14a8be9428435ee17f17fae7991215c246b7fd43`
- `Linux >= 57a304cfd43b2b4a5b44b8f5dc026abb34183068 < 797dc567146c7e3c4f8d9680e4fbc76e0a6d9151`
- `Linux >= 57a304cfd43b2b4a5b44b8f5dc026abb34183068 < ae0629ff9ccb836416ada129f4edc7efea6eaaad`
- `Linux >= 57a304cfd43b2b4a5b44b8f5dc026abb34183068 < 6a8269b6459ed870a8156c106a0f597383907872`
- `Linux 5.13`

## Remediation

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