Vulnerability-Lookup

BDU:2026-01221 (CVE-2023-54121)

Vulnerability from fstec – Published: 2026-02-04 – Updated: 2026-02-04 – View on bdu.fstec.ru Fixed

Title

Уязвимость функции btrfs_drop_extent_map_range() модуля fs/btrfs/extent_map.c файловой системы btrfs ядра операционной системы Linux, позволяющая нарушителю вызвать отказ в обслуживании

Summary

Уязвимость функции btrfs_drop_extent_map_range() модуля fs/btrfs/extent_map.c файловой системы btrfs ядра операционной системы Linux связана с выполнением цикла с недоступным условием выхода(«Бесконечный цикл»). Эксплуатация уязвимости может позволить нарушителю вызвать отказ в обслуживании

Severity

4.6 (Medium) CVSS 2.0


                      
                        AV:L/AC:L/Au:S/C:N/I:N/A:C

5.5 (Medium) CVSS 3.1


                      
                        CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Class

Code vulnerability

Status

Confirmed by the vendor

Exploitation

Resource exhaustion

Incidents

Being clarified

Remediation

Software update

CWE

CWE-835 - Выполнение цикла с недоступным условием выхода (бесконечный цикл)

Aliases

CVE-2023-54121

References

9 references

URL
https://www.cve.org/CVERecord?id=CVE-2023-54121
https://git.kernel.org/stable/c/9f68e2105dd96cf0fafffffafb2337fbd0fbae1f
https://git.kernel.org/stable/c/b43a4c99d878cf5e59040e45c96bb0a8358bfb3b
https://git.kernel.org/stable/c/c962098ca4af146f2625ed64399926a098752c9c
https://kernel.org/pub/linux/kernel/v6.x/ChangeLog-6.1.47
https://kernel.org/pub/linux/kernel/v6.x/ChangeLog-6.4.12
https://lore.kernel.org/linux-cve-announce/2025122416-CVE-2023-54121-691a@gregkh/
https://security-tracker.debian.org/tracker/CVE-2023-54121
https://access.redhat.com/security/cve/cve-2023-54121

Impacted products

3 products from 3 vendors

Vendors

Red Hat, Inc., Сообщество свободного программного обеспечения

Products

Red Hat Enterprise Linux, Debian GNU/Linux, Linux

Versions

7 (Red Hat Enterprise Linux), 12 (Debian GNU/Linux), от 6.2 до 6.4.11 включительно (Linux), от 2.6.33 до 6.1.46 включительно (Linux)

Product types

Operating system

Platforms

Red Hat, Inc. Red Hat Enterprise Linux 7, Сообщество свободного программного обеспечения Debian GNU/Linux 12, Сообщество свободного программного обеспечения Linux от 6.2 до 6.4.11 включительно, Сообщество свободного программного обеспечения Linux от 2.6.33 до 6.1.46 включительно

Mitigations

В условиях отсутствия обновлений безопасности от производителя рекомендуется придерживаться "Рекомендаций по безопасной настройке операционных систем LINUX", изложенных в методическом документе ФСТЭК России, утверждённом 25 декабря 2022 года. Использование рекомендаций: Для Linux: https://lore.kernel.org/linux-cve-announce/2025122416-CVE-2023-54121-691a@gregkh/ https://git.kernel.org/stable/c/9f68e2105dd96cf0fafffffafb2337fbd0fbae1f https://git.kernel.org/stable/c/b43a4c99d878cf5e59040e45c96bb0a8358bfb3b https://git.kernel.org/stable/c/c962098ca4af146f2625ed64399926a098752c9c https://kernel.org/pub/linux/kernel/v6.x/ChangeLog-6.1.47 https://kernel.org/pub/linux/kernel/v6.x/ChangeLog-6.4.12 Для Debian GNU/Linux: https://security-tracker.debian.org/tracker/CVE-2023-54121 Для продуктов Red Hat Inc.: https://access.redhat.com/security/cve/cve-2023-54121

JSON

To clipboard

{
  "CVSS 2.0": "AV:L/AC:L/Au:S/C:N/I:N/A:C",
  "CVSS 3.0": "AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
  "CVSS 4.0": null,
  "remediation_\u0418\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440": null,
  "remediation_\u041d\u0430\u0438\u043c\u0435\u043d\u043e\u0432\u0430\u043d\u0438\u0435": null,
  "\u0412\u0435\u043d\u0434\u043e\u0440 \u041f\u041e": "Red Hat, Inc., \u0421\u043e\u043e\u0431\u0449\u0435\u0441\u0442\u0432\u043e \u0441\u0432\u043e\u0431\u043e\u0434\u043d\u043e\u0433\u043e \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u043d\u043e\u0433\u043e \u043e\u0431\u0435\u0441\u043f\u0435\u0447\u0435\u043d\u0438\u044f",
  "\u0412\u0435\u0440\u0441\u0438\u044f \u041f\u041e": "7 (Red Hat Enterprise Linux), 12 (Debian GNU/Linux), \u043e\u0442 6.2 \u0434\u043e 6.4.11 \u0432\u043a\u043b\u044e\u0447\u0438\u0442\u0435\u043b\u044c\u043d\u043e (Linux), \u043e\u0442 2.6.33 \u0434\u043e 6.1.46 \u0432\u043a\u043b\u044e\u0447\u0438\u0442\u0435\u043b\u044c\u043d\u043e (Linux)",
  "\u0412\u043e\u0437\u043c\u043e\u0436\u043d\u044b\u0435 \u043c\u0435\u0440\u044b \u043f\u043e \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u044e": "\u0412 \u0443\u0441\u043b\u043e\u0432\u0438\u044f\u0445 \u043e\u0442\u0441\u0443\u0442\u0441\u0442\u0432\u0438\u044f \u043e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u0439 \u0431\u0435\u0437\u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 \u043e\u0442 \u043f\u0440\u043e\u0438\u0437\u0432\u043e\u0434\u0438\u0442\u0435\u043b\u044f \u0440\u0435\u043a\u043e\u043c\u0435\u043d\u0434\u0443\u0435\u0442\u0441\u044f \u043f\u0440\u0438\u0434\u0435\u0440\u0436\u0438\u0432\u0430\u0442\u044c\u0441\u044f \"\u0420\u0435\u043a\u043e\u043c\u0435\u043d\u0434\u0430\u0446\u0438\u0439 \u043f\u043e \u0431\u0435\u0437\u043e\u043f\u0430\u0441\u043d\u043e\u0439 \u043d\u0430\u0441\u0442\u0440\u043e\u0439\u043a\u0435 \u043e\u043f\u0435\u0440\u0430\u0446\u0438\u043e\u043d\u043d\u044b\u0445 \u0441\u0438\u0441\u0442\u0435\u043c LINUX\", \u0438\u0437\u043b\u043e\u0436\u0435\u043d\u043d\u044b\u0445 \u0432 \u043c\u0435\u0442\u043e\u0434\u0438\u0447\u0435\u0441\u043a\u043e\u043c \u0434\u043e\u043a\u0443\u043c\u0435\u043d\u0442\u0435 \u0424\u0421\u0422\u042d\u041a \u0420\u043e\u0441\u0441\u0438\u0438, \u0443\u0442\u0432\u0435\u0440\u0436\u0434\u0451\u043d\u043d\u043e\u043c 25 \u0434\u0435\u043a\u0430\u0431\u0440\u044f 2022 \u0433\u043e\u0434\u0430.\n\n\n\n\u0418\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0435 \u0440\u0435\u043a\u043e\u043c\u0435\u043d\u0434\u0430\u0446\u0438\u0439:\n\n\u0414\u043b\u044f Linux:\nhttps://lore.kernel.org/linux-cve-announce/2025122416-CVE-2023-54121-691a@gregkh/\nhttps://git.kernel.org/stable/c/9f68e2105dd96cf0fafffffafb2337fbd0fbae1f\nhttps://git.kernel.org/stable/c/b43a4c99d878cf5e59040e45c96bb0a8358bfb3b\nhttps://git.kernel.org/stable/c/c962098ca4af146f2625ed64399926a098752c9c\nhttps://kernel.org/pub/linux/kernel/v6.x/ChangeLog-6.1.47\nhttps://kernel.org/pub/linux/kernel/v6.x/ChangeLog-6.4.12\n\n\u0414\u043b\u044f Debian GNU/Linux:\nhttps://security-tracker.debian.org/tracker/CVE-2023-54121\n\n\u0414\u043b\u044f \u043f\u0440\u043e\u0434\u0443\u043a\u0442\u043e\u0432 Red Hat Inc.:\nhttps://access.redhat.com/security/cve/cve-2023-54121",
  "\u0414\u0430\u0442\u0430 \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0438\u044f": "18.08.2023",
  "\u0414\u0430\u0442\u0430 \u043f\u043e\u0441\u043b\u0435\u0434\u043d\u0435\u0433\u043e \u043e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u044f": "04.02.2026",
  "\u0414\u0430\u0442\u0430 \u043f\u0443\u0431\u043b\u0438\u043a\u0430\u0446\u0438\u0438": "04.02.2026",
  "\u0418\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440": "BDU:2026-01221",
  "\u0418\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440\u044b \u0434\u0440\u0443\u0433\u0438\u0445 \u0441\u0438\u0441\u0442\u0435\u043c \u043e\u043f\u0438\u0441\u0430\u043d\u0438\u0439 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "CVE-2023-54121",
  "\u0418\u043d\u0444\u043e\u0440\u043c\u0430\u0446\u0438\u044f \u043e\u0431 \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0430",
  "\u041a\u043b\u0430\u0441\u0441 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u043a\u043e\u0434\u0430",
  "\u041d\u0430\u0437\u0432\u0430\u043d\u0438\u0435 \u041f\u041e": "Red Hat Enterprise Linux, Debian GNU/Linux, Linux",
  "\u041d\u0430\u0438\u043c\u0435\u043d\u043e\u0432\u0430\u043d\u0438\u0435 \u041e\u0421 \u0438 \u0442\u0438\u043f \u0430\u043f\u043f\u0430\u0440\u0430\u0442\u043d\u043e\u0439 \u043f\u043b\u0430\u0442\u0444\u043e\u0440\u043c\u044b": "Red Hat, Inc. Red Hat Enterprise Linux 7 , \u0421\u043e\u043e\u0431\u0449\u0435\u0441\u0442\u0432\u043e \u0441\u0432\u043e\u0431\u043e\u0434\u043d\u043e\u0433\u043e \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u043d\u043e\u0433\u043e \u043e\u0431\u0435\u0441\u043f\u0435\u0447\u0435\u043d\u0438\u044f Debian GNU/Linux 12 , \u0421\u043e\u043e\u0431\u0449\u0435\u0441\u0442\u0432\u043e \u0441\u0432\u043e\u0431\u043e\u0434\u043d\u043e\u0433\u043e \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u043d\u043e\u0433\u043e \u043e\u0431\u0435\u0441\u043f\u0435\u0447\u0435\u043d\u0438\u044f Linux \u043e\u0442 6.2 \u0434\u043e 6.4.11 \u0432\u043a\u043b\u044e\u0447\u0438\u0442\u0435\u043b\u044c\u043d\u043e , \u0421\u043e\u043e\u0431\u0449\u0435\u0441\u0442\u0432\u043e \u0441\u0432\u043e\u0431\u043e\u0434\u043d\u043e\u0433\u043e \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u043d\u043e\u0433\u043e \u043e\u0431\u0435\u0441\u043f\u0435\u0447\u0435\u043d\u0438\u044f Linux \u043e\u0442 2.6.33 \u0434\u043e 6.1.46 \u0432\u043a\u043b\u044e\u0447\u0438\u0442\u0435\u043b\u044c\u043d\u043e ",
  "\u041d\u0430\u0438\u043c\u0435\u043d\u043e\u0432\u0430\u043d\u0438\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0444\u0443\u043d\u043a\u0446\u0438\u0438 btrfs_drop_extent_map_range() \u043c\u043e\u0434\u0443\u043b\u044f fs/btrfs/extent_map.c \u0444\u0430\u0439\u043b\u043e\u0432\u043e\u0439 \u0441\u0438\u0441\u0442\u0435\u043c\u044b btrfs \u044f\u0434\u0440\u0430 \u043e\u043f\u0435\u0440\u0430\u0446\u0438\u043e\u043d\u043d\u043e\u0439 \u0441\u0438\u0441\u0442\u0435\u043c\u044b Linux, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u043d\u0430\u0440\u0443\u0448\u0438\u0442\u0435\u043b\u044e \u0432\u044b\u0437\u0432\u0430\u0442\u044c \u043e\u0442\u043a\u0430\u0437 \u0432 \u043e\u0431\u0441\u043b\u0443\u0436\u0438\u0432\u0430\u043d\u0438\u0438",
  "\u041d\u0430\u043b\u0438\u0447\u0438\u0435 \u044d\u043a\u0441\u043f\u043b\u043e\u0439\u0442\u0430": "\u0414\u0430\u043d\u043d\u044b\u0435 \u0443\u0442\u043e\u0447\u043d\u044f\u044e\u0442\u0441\u044f",
  "\u041e\u043f\u0438\u0441\u0430\u043d\u0438\u0435 \u043e\u0448\u0438\u0431\u043a\u0438 CWE": "\u0412\u044b\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u0435 \u0446\u0438\u043a\u043b\u0430 \u0441 \u043d\u0435\u0434\u043e\u0441\u0442\u0443\u043f\u043d\u044b\u043c \u0443\u0441\u043b\u043e\u0432\u0438\u0435\u043c \u0432\u044b\u0445\u043e\u0434\u0430 (\u0431\u0435\u0441\u043a\u043e\u043d\u0435\u0447\u043d\u044b\u0439 \u0446\u0438\u043a\u043b) (CWE-835)",
  "\u041e\u043f\u0438\u0441\u0430\u043d\u0438\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0444\u0443\u043d\u043a\u0446\u0438\u0438 btrfs_drop_extent_map_range() \u043c\u043e\u0434\u0443\u043b\u044f fs/btrfs/extent_map.c \u0444\u0430\u0439\u043b\u043e\u0432\u043e\u0439 \u0441\u0438\u0441\u0442\u0435\u043c\u044b btrfs \u044f\u0434\u0440\u0430 \u043e\u043f\u0435\u0440\u0430\u0446\u0438\u043e\u043d\u043d\u043e\u0439 \u0441\u0438\u0441\u0442\u0435\u043c\u044b Linux \u0441\u0432\u044f\u0437\u0430\u043d\u0430 \u0441 \u0432\u044b\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u0435\u043c \u0446\u0438\u043a\u043b\u0430 \u0441 \u043d\u0435\u0434\u043e\u0441\u0442\u0443\u043f\u043d\u044b\u043c \u0443\u0441\u043b\u043e\u0432\u0438\u0435\u043c \u0432\u044b\u0445\u043e\u0434\u0430(\u00ab\u0411\u0435\u0441\u043a\u043e\u043d\u0435\u0447\u043d\u044b\u0439 \u0446\u0438\u043a\u043b\u00bb). \u042d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0430\u0446\u0438\u044f \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 \u043c\u043e\u0436\u0435\u0442 \u043f\u043e\u0437\u0432\u043e\u043b\u0438\u0442\u044c \u043d\u0430\u0440\u0443\u0448\u0438\u0442\u0435\u043b\u044e \u0432\u044b\u0437\u0432\u0430\u0442\u044c \u043e\u0442\u043a\u0430\u0437 \u0432 \u043e\u0431\u0441\u043b\u0443\u0436\u0438\u0432\u0430\u043d\u0438\u0438",
  "\u041f\u043e\u0441\u043b\u0435\u0434\u0441\u0442\u0432\u0438\u044f \u044d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0430\u0446\u0438\u0438 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": null,
  "\u041f\u0440\u043e\u0447\u0430\u044f \u0438\u043d\u0444\u043e\u0440\u043c\u0430\u0446\u0438\u044f": null,
  "\u0421\u0432\u044f\u0437\u044c \u0441 \u0438\u043d\u0446\u0438\u0434\u0435\u043d\u0442\u0430\u043c\u0438 \u0418\u0411": "\u0414\u0430\u043d\u043d\u044b\u0435 \u0443\u0442\u043e\u0447\u043d\u044f\u044e\u0442\u0441\u044f",
  "\u0421\u043e\u0441\u0442\u043e\u044f\u043d\u0438\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u041e\u043f\u0443\u0431\u043b\u0438\u043a\u043e\u0432\u0430\u043d\u0430",
  "\u0421\u043f\u043e\u0441\u043e\u0431 \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u044f": "\u041e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u0435 \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u043d\u043e\u0433\u043e \u043e\u0431\u0435\u0441\u043f\u0435\u0447\u0435\u043d\u0438\u044f",
  "\u0421\u043f\u043e\u0441\u043e\u0431 \u044d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0430\u0446\u0438\u0438": "\u0418\u0441\u0447\u0435\u0440\u043f\u0430\u043d\u0438\u0435 \u0440\u0435\u0441\u0443\u0440\u0441\u043e\u0432",
  "\u0421\u0441\u044b\u043b\u043a\u0438 \u043d\u0430 \u0438\u0441\u0442\u043e\u0447\u043d\u0438\u043a\u0438": "https://www.cve.org/CVERecord?id=CVE-2023-54121\nhttps://git.kernel.org/stable/c/9f68e2105dd96cf0fafffffafb2337fbd0fbae1f\nhttps://git.kernel.org/stable/c/b43a4c99d878cf5e59040e45c96bb0a8358bfb3b\nhttps://git.kernel.org/stable/c/c962098ca4af146f2625ed64399926a098752c9c\nhttps://kernel.org/pub/linux/kernel/v6.x/ChangeLog-6.1.47\nhttps://kernel.org/pub/linux/kernel/v6.x/ChangeLog-6.4.12\nhttps://lore.kernel.org/linux-cve-announce/2025122416-CVE-2023-54121-691a@gregkh/\nhttps://security-tracker.debian.org/tracker/CVE-2023-54121\nhttps://access.redhat.com/security/cve/cve-2023-54121",
  "\u0421\u0442\u0430\u0442\u0443\u0441 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u041f\u043e\u0434\u0442\u0432\u0435\u0440\u0436\u0434\u0435\u043d\u0430 \u043f\u0440\u043e\u0438\u0437\u0432\u043e\u0434\u0438\u0442\u0435\u043b\u0435\u043c",
  "\u0422\u0438\u043f \u041f\u041e": "\u041e\u043f\u0435\u0440\u0430\u0446\u0438\u043e\u043d\u043d\u0430\u044f \u0441\u0438\u0441\u0442\u0435\u043c\u0430",
  "\u0422\u0438\u043f \u043e\u0448\u0438\u0431\u043a\u0438 CWE": "CWE-835",
  "\u0423\u0440\u043e\u0432\u0435\u043d\u044c \u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0421\u0440\u0435\u0434\u043d\u0438\u0439 \u0443\u0440\u043e\u0432\u0435\u043d\u044c \u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 (\u0431\u0430\u0437\u043e\u0432\u0430\u044f \u043e\u0446\u0435\u043d\u043a\u0430 CVSS 2.0 \u0441\u043e\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u0442 4,6)\n\u0421\u0440\u0435\u0434\u043d\u0438\u0439 \u0443\u0440\u043e\u0432\u0435\u043d\u044c \u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 (\u0431\u0430\u0437\u043e\u0432\u0430\u044f \u043e\u0446\u0435\u043d\u043a\u0430 CVSS 3.1 \u0441\u043e\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u0442 5,5)"
}

CVE-2023-54121 (GCVE-0-2023-54121)

Vulnerability from cvelistv5 – Published: 2025-12-24 13:06 – Updated: 2026-08-05 09:17

Title

btrfs: fix incorrect splitting in btrfs_drop_extent_map_range

Summary

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix incorrect splitting in btrfs_drop_extent_map_range In production we were seeing a variety of WARN_ON()'s in the extent_map code, specifically in btrfs_drop_extent_map_range() when we have to call add_extent_mapping() for our second split. Consider the following extent map layout PINNED [0 16K) [32K, 48K) and then we call btrfs_drop_extent_map_range for [0, 36K), with skip_pinned == true. The initial loop will have start = 0 end = 36K len = 36K we will find the [0, 16k) extent, but since we are pinned we will skip it, which has this code start = em_end; if (end != (u64)-1) len = start + len - em_end; em_end here is 16K, so now the values are start = 16K len = 16K + 36K - 16K = 36K len should instead be 20K. This is a problem when we find the next extent at [32K, 48K), we need to split this extent to leave [36K, 48k), however the code for the split looks like this split->start = start + len; split->len = em_end - (start + len); In this case we have em_end = 48K split->start = 16K + 36K // this should be 16K + 20K split->len = 48K - (16K + 36K) // this overflows as 16K + 36K is 52K and now we have an invalid extent_map in the tree that potentially overlaps other entries in the extent map. Even in the non-overlapping case we will have split->start set improperly, which will cause problems with any block related calculations. We don't actually need len in this loop, we can simply use end as our end point, and only adjust start up when we find a pinned extent we need to skip. Adjust the logic to do this, which keeps us from inserting an invalid extent map. We only skip_pinned in the relocation case, so this is relatively rare, except in the case where you are running relocation a lot, which can happen with auto relocation on.

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root

References

3 references

URL	Tags
https://git.kernel.org/stable/c/9f68e2105dd96cf0f…
https://git.kernel.org/stable/c/b43a4c99d878cf5e5…
https://git.kernel.org/stable/c/c962098ca4af146f2…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 55ef68990029fcd8d04d42fc184aa7fb18cf309e , < 9f68e2105dd96cf0fafffffafb2337fbd0fbae1f (git) Affected: 55ef68990029fcd8d04d42fc184aa7fb18cf309e , < b43a4c99d878cf5e59040e45c96bb0a8358bfb3b (git) Affected: 55ef68990029fcd8d04d42fc184aa7fb18cf309e , < c962098ca4af146f2625ed64399926a098752c9c (git) Affected: c87afd35a28b2661a2626a1b28e9fd69adcad9f9 (git) Affected: 2.6.32.19 , < 2.6.33 (semver)
Linux	Linux	Affected: 2.6.33 Unaffected: 0 , < 2.6.33 (semver) Unaffected: 6.1.47 , ≤ 6.1.* (semver) Unaffected: 6.4.12 , ≤ 6.4.* (semver) Unaffected: 6.5 , ≤ * (original_commit_for_fix)

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{
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        {
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          "product": "Linux",
          "programFiles": [
            "fs/btrfs/extent_map.c"
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              "version": "2.6.33"
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                {
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                  "vulnerable": true
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                {
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        {
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix incorrect splitting in btrfs_drop_extent_map_range\n\nIn production we were seeing a variety of WARN_ON()\u0027s in the extent_map\ncode, specifically in btrfs_drop_extent_map_range() when we have to call\nadd_extent_mapping() for our second split.\n\nConsider the following extent map layout\n\n\tPINNED\n\t[0 16K)  [32K, 48K)\n\nand then we call btrfs_drop_extent_map_range for [0, 36K), with\nskip_pinned == true.  The initial loop will have\n\n\tstart = 0\n\tend = 36K\n\tlen = 36K\n\nwe will find the [0, 16k) extent, but since we are pinned we will skip\nit, which has this code\n\n\tstart = em_end;\n\tif (end != (u64)-1)\n\t\tlen = start + len - em_end;\n\nem_end here is 16K, so now the values are\n\n\tstart = 16K\n\tlen = 16K + 36K - 16K = 36K\n\nlen should instead be 20K.  This is a problem when we find the next\nextent at [32K, 48K), we need to split this extent to leave [36K, 48k),\nhowever the code for the split looks like this\n\n\tsplit-\u003estart = start + len;\n\tsplit-\u003elen = em_end - (start + len);\n\nIn this case we have\n\n\tem_end = 48K\n\tsplit-\u003estart = 16K + 36K       // this should be 16K + 20K\n\tsplit-\u003elen = 48K - (16K + 36K) // this overflows as 16K + 36K is 52K\n\nand now we have an invalid extent_map in the tree that potentially\noverlaps other entries in the extent map.  Even in the non-overlapping\ncase we will have split-\u003estart set improperly, which will cause problems\nwith any block related calculations.\n\nWe don\u0027t actually need len in this loop, we can simply use end as our\nend point, and only adjust start up when we find a pinned extent we need\nto skip.\n\nAdjust the logic to do this, which keeps us from inserting an invalid\nextent map.\n\nWe only skip_pinned in the relocation case, so this is relatively rare,\nexcept in the case where you are running relocation a lot, which can\nhappen with auto relocation on."
        }
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              "value": "AV:L - The bug is triggered through local filesystem operations on a mounted btrfs \u2014 ordinary writes creating pinned extent maps combined with the in-kernel relocation path. No network or remote peer data is involved.\nAC:L - The attacker fully controls the extent-map layout side (writes create EXTENT_FLAG_PINNED maps via create_io_em(), and file layout/extent sizes are attacker-chosen) and can maintain it continuously; relocation recurs automatically on zoned btrfs (bg_reclaim_threshold=75 by default, drivable by filling then deleting data) and via routine distro balance timers, so no condition is genuinely outside attacker influence.\nPR:L - The attacker\u0027s side of the trigger requires only an unprivileged local account with write access to a btrfs filesystem \u2014 plain write(2)/fallocate paths with no capability check reach create_io_em() and the extent map tree. No CAP_SYS_ADMIN is needed on the attacker\u0027s own path.\nUI:N - No victim action is required \u2014 automatic block-group reclaim and scheduled relocation run as background kernel work, and the corrupting split happens without any interactive step by another user.\nS:U - The corruption is confined to the kernel\u0027s own extent map tree and the filesystem it manages; no VM, IOMMU, or sandbox security boundary is crossed.\nC:H - The inserted extent map carries a wrong block_start (off by the skipped pinned extent\u0027s size) and an underflowed length, and the resulting extent_offset underflow in btrfs_do_readpage() makes disk_bytenr point at attacker-influenced wrong logical addresses, pulling other files\u0027 on-disk data into the attacker\u0027s page cache.\nI:H - The same bogus block_start/block_len feed the writeback and direct-I/O paths, so data can be written to disk locations belonging to other files, and the em rbtree ordering invariant is violated (extent_map_end wraps below start), propagating further corruption through merge_extent_mapping().\nA:H - Production-observed WARN_ON()s in add_extent_mapping(), ASSERT(ret == 0) which is a BUG() with CONFIG_BTRFS_ASSERT, u64 length underflow to ~2^64, and inconsistent extent map trees leading to transaction abort and forced read-only remount or panic on panic_on_warn systems."
            }
          ]
        }
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      "providerMetadata": {
        "dateUpdated": "2026-08-05T09:17:24.043Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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          "url": "https://git.kernel.org/stable/c/c962098ca4af146f2625ed64399926a098752c9c"
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      "title": "btrfs: fix incorrect splitting in btrfs_drop_extent_map_range",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2023-54121",
    "datePublished": "2025-12-24T13:06:41.185Z",
    "dateReserved": "2025-12-24T13:02:52.520Z",
    "dateUpdated": "2026-08-05T09:17:24.043Z",
    "state": "PUBLISHED"
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}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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BDU:2026-01221 (CVE-2023-54121)

CVE-2023-54121 (GCVE-0-2023-54121)

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