Vulnerability-Lookup

BDU:2025-13577 (CVE-2025-40007)

Vulnerability from fstec – Published: 2025-10-30 – Updated: 2025-10-30 – View on bdu.fstec.ru Fixed

Title

Уязвимость функции netfs_alloc_request() ядра операционной системы Linux, позволяющая нарушителю вызвать отказ в обслуживании

Summary

Уязвимость функции netfs_alloc_request() ядра операционной системы Linux связана с ошибками при обновлении счетчика ссылок. 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 manipulation

Incidents

Being clarified

Remediation

Software update

CWE

CWE-911 - Неправильное обновление счетчика ссылок

Aliases

CVE-2025-40007

References

4 references

URL
https://lore.kernel.org/linux-cve-announce/2025102002-CVE-2025-40007-3315@gregkh/
https://git.kernel.org/stable/c/4d428dca252c858bfac691c31fa95d26cd008706
https://git.kernel.org/stable/c/8df142e93098b4531fadb5dfcf93087649f570b3
https://access.redhat.com/security/cve/cve-2025-40007

Impacted products

2 products from 3 vendors

Vendors

Red Hat, Inc., Сообщество свободного программного обеспечения

Products

Red Hat Enterprise Linux, Linux

Versions

10 (Red Hat Enterprise Linux), до 6.17 (Linux), от 6.16 до 6.16.10 (Linux), 6.15.3 (Linux)

Product types

Operating system

Platforms

Red Hat, Inc. Red Hat Enterprise Linux 10, Сообщество свободного программного обеспечения Linux до 6.17, Сообщество свободного программного обеспечения Linux от 6.16 до 6.16.10, Сообщество свободного программного обеспечения Linux 6.15.3

Mitigations

Использование рекомендаций: Для Linux: https://lore.kernel.org/linux-cve-announce/2025102002-CVE-2025-40007-3315@gregkh/ https://git.kernel.org/stable/c/4d428dca252c858bfac691c31fa95d26cd008706 https://git.kernel.org/stable/c/8df142e93098b4531fadb5dfcf93087649f570b3 Для продуктов Red Hat Inc.: https://access.redhat.com/security/cve/cve-2025-40007 Компенсирующие меры: 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.

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": "10 (Red Hat Enterprise Linux), \u0434\u043e 6.17 (Linux), \u043e\u0442 6.16 \u0434\u043e 6.16.10 (Linux), 6.15.3 (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": "\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\u0414\u043b\u044f Linux: \nhttps://lore.kernel.org/linux-cve-announce/2025102002-CVE-2025-40007-3315@gregkh/\nhttps://git.kernel.org/stable/c/4d428dca252c858bfac691c31fa95d26cd008706 \nhttps://git.kernel.org/stable/c/8df142e93098b4531fadb5dfcf93087649f570b3\n\n\u0414\u043b\u044f \u043f\u0440\u043e\u0434\u0443\u043a\u0442\u043e\u0432 Red Hat Inc.:\nhttps://access.redhat.com/security/cve/cve-2025-40007\n\n\u041a\u043e\u043c\u043f\u0435\u043d\u0441\u0438\u0440\u0443\u044e\u0449\u0438\u0435 \u043c\u0435\u0440\u044b:\n\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.",
  "\u0414\u0430\u0442\u0430 \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0438\u044f": "25.09.2025",
  "\u0414\u0430\u0442\u0430 \u043f\u043e\u0441\u043b\u0435\u0434\u043d\u0435\u0433\u043e \u043e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u044f": "30.10.2025",
  "\u0414\u0430\u0442\u0430 \u043f\u0443\u0431\u043b\u0438\u043a\u0430\u0446\u0438\u0438": "30.10.2025",
  "\u0418\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440": "BDU:2025-13577",
  "\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-2025-40007",
  "\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, 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 10 , \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 \u0434\u043e 6.17 , \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 6.16 \u0434\u043e 6.16.10 , \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 6.15.3 ",
  "\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 netfs_alloc_request() \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": "\u041d\u0435\u043f\u0440\u0430\u0432\u0438\u043b\u044c\u043d\u043e\u0435 \u043e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u0435 \u0441\u0447\u0435\u0442\u0447\u0438\u043a\u0430 \u0441\u0441\u044b\u043b\u043e\u043a (CWE-911)",
  "\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 netfs_alloc_request() \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 \u043e\u0448\u0438\u0431\u043a\u0430\u043c\u0438 \u043f\u0440\u0438 \u043e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u0438 \u0441\u0447\u0435\u0442\u0447\u0438\u043a\u0430 \u0441\u0441\u044b\u043b\u043e\u043a. \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": "\u041c\u0430\u043d\u0438\u043f\u0443\u043b\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u0435 \u0440\u0435\u0441\u0443\u0440\u0441\u0430\u043c\u0438",
  "\u0421\u0441\u044b\u043b\u043a\u0438 \u043d\u0430 \u0438\u0441\u0442\u043e\u0447\u043d\u0438\u043a\u0438": "https://lore.kernel.org/linux-cve-announce/2025102002-CVE-2025-40007-3315@gregkh/\nhttps://git.kernel.org/stable/c/4d428dca252c858bfac691c31fa95d26cd008706 \nhttps://git.kernel.org/stable/c/8df142e93098b4531fadb5dfcf93087649f570b3\nhttps://access.redhat.com/security/cve/cve-2025-40007",
  "\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-911",
  "\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-2025-40007 (GCVE-0-2025-40007)

Vulnerability from cvelistv5 – Published: 2025-10-20 15:26 – Updated: 2026-05-23 16:01

Title

netfs: fix reference leak

Summary

In the Linux kernel, the following vulnerability has been resolved: netfs: fix reference leak Commit 20d72b00ca81 ("netfs: Fix the request's work item to not require a ref") modified netfs_alloc_request() to initialize the reference counter to 2 instead of 1. The rationale was that the requet's "work" would release the second reference after completion (via netfs_{read,write}_collection_worker()). That works most of the time if all goes well. However, it leaks this additional reference if the request is released before the I/O operation has been submitted: the error code path only decrements the reference counter once and the work item will never be queued because there will never be a completion. This has caused outages of our whole server cluster today because tasks were blocked in netfs_wait_for_outstanding_io(), leading to deadlocks in Ceph (another bug that I will address soon in another patch). This was caused by a netfs_pgpriv2_begin_copy_to_cache() call which failed in fscache_begin_write_operation(). The leaked netfs_io_request was never completed, leaving `netfs_inode.io_count` with a positive value forever. All of this is super-fragile code. Finding out which code paths will lead to an eventual completion and which do not is hard to see: - Some functions like netfs_create_write_req() allocate a request, but will never submit any I/O. - netfs_unbuffered_read_iter_locked() calls netfs_unbuffered_read() and then netfs_put_request(); however, netfs_unbuffered_read() can also fail early before submitting the I/O request, therefore another netfs_put_request() call must be added there. A rule of thumb is that functions that return a `netfs_io_request` do not submit I/O, and all of their callers must be checked. For my taste, the whole netfs code needs an overhaul to make reference counting easier to understand and less fragile & obscure. But to fix this bug here and now and produce a patch that is adequate for a stable backport, I tried a minimal approach that quickly frees the request object upon early failure. I decided against adding a second netfs_put_request() each time because that would cause code duplication which obscures the code further. Instead, I added the function netfs_put_failed_request() which frees such a failed request synchronously under the assumption that the reference count is exactly 2 (as initially set by netfs_alloc_request() and never touched), verified by a WARN_ON_ONCE(). It then deinitializes the request object (without going through the "cleanup_work" indirection) and frees the allocation (with RCU protection to protect against concurrent access by netfs_requests_seq_start()). All code paths that fail early have been changed to call netfs_put_failed_request() instead of netfs_put_request(). Additionally, I have added a netfs_put_request() call to netfs_unbuffered_read() as explained above because the netfs_put_failed_request() approach does not work there.

Severity

No CVSS data available.

Assigner

Linux mitre root

References

2 references

URL	Tags
https://git.kernel.org/stable/c/8df142e93098b4531…
https://git.kernel.org/stable/c/4d428dca252c858bf…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 20d72b00ca814d748f5663484e5c53bb2bf37a3a , < 8df142e93098b4531fadb5dfcf93087649f570b3 (git) Affected: 20d72b00ca814d748f5663484e5c53bb2bf37a3a , < 4d428dca252c858bfac691c31fa95d26cd008706 (git) Affected: 1a8360c2eed3b292ed654c2ac61b09de4a80e298 (git) Affected: 6.15.3 , < 6.16 (semver)
Linux	Linux	Affected: 6.16 Unaffected: 0 , < 6.16 (semver) Unaffected: 6.16.10 , ≤ 6.16.* (semver) Unaffected: 6.17 , ≤ * (original_commit_for_fix)

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          "programFiles": [
            "fs/netfs/buffered_read.c",
            "fs/netfs/direct_read.c",
            "fs/netfs/direct_write.c",
            "fs/netfs/internal.h",
            "fs/netfs/objects.c",
            "fs/netfs/read_pgpriv2.c",
            "fs/netfs/read_single.c",
            "fs/netfs/write_issue.c"
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            "fs/netfs/read_pgpriv2.c",
            "fs/netfs/read_single.c",
            "fs/netfs/write_issue.c"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfs: fix reference leak\n\nCommit 20d72b00ca81 (\"netfs: Fix the request\u0027s work item to not\nrequire a ref\") modified netfs_alloc_request() to initialize the\nreference counter to 2 instead of 1.  The rationale was that the\nrequet\u0027s \"work\" would release the second reference after completion\n(via netfs_{read,write}_collection_worker()).  That works most of the\ntime if all goes well.\n\nHowever, it leaks this additional reference if the request is released\nbefore the I/O operation has been submitted: the error code path only\ndecrements the reference counter once and the work item will never be\nqueued because there will never be a completion.\n\nThis has caused outages of our whole server cluster today because\ntasks were blocked in netfs_wait_for_outstanding_io(), leading to\ndeadlocks in Ceph (another bug that I will address soon in another\npatch).  This was caused by a netfs_pgpriv2_begin_copy_to_cache() call\nwhich failed in fscache_begin_write_operation().  The leaked\nnetfs_io_request was never completed, leaving `netfs_inode.io_count`\nwith a positive value forever.\n\nAll of this is super-fragile code.  Finding out which code paths will\nlead to an eventual completion and which do not is hard to see:\n\n- Some functions like netfs_create_write_req() allocate a request, but\n  will never submit any I/O.\n\n- netfs_unbuffered_read_iter_locked() calls netfs_unbuffered_read()\n  and then netfs_put_request(); however, netfs_unbuffered_read() can\n  also fail early before submitting the I/O request, therefore another\n  netfs_put_request() call must be added there.\n\nA rule of thumb is that functions that return a `netfs_io_request` do\nnot submit I/O, and all of their callers must be checked.\n\nFor my taste, the whole netfs code needs an overhaul to make reference\ncounting easier to understand and less fragile \u0026 obscure.  But to fix\nthis bug here and now and produce a patch that is adequate for a\nstable backport, I tried a minimal approach that quickly frees the\nrequest object upon early failure.\n\nI decided against adding a second netfs_put_request() each time\nbecause that would cause code duplication which obscures the code\nfurther.  Instead, I added the function netfs_put_failed_request()\nwhich frees such a failed request synchronously under the assumption\nthat the reference count is exactly 2 (as initially set by\nnetfs_alloc_request() and never touched), verified by a\nWARN_ON_ONCE().  It then deinitializes the request object (without\ngoing through the \"cleanup_work\" indirection) and frees the allocation\n(with RCU protection to protect against concurrent access by\nnetfs_requests_seq_start()).\n\nAll code paths that fail early have been changed to call\nnetfs_put_failed_request() instead of netfs_put_request().\nAdditionally, I have added a netfs_put_request() call to\nnetfs_unbuffered_read() as explained above because the\nnetfs_put_failed_request() approach does not work there."
        }
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        "dateUpdated": "2026-05-23T16:01:14.674Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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          "url": "https://git.kernel.org/stable/c/8df142e93098b4531fadb5dfcf93087649f570b3"
        },
        {
          "url": "https://git.kernel.org/stable/c/4d428dca252c858bfac691c31fa95d26cd008706"
        }
      ],
      "title": "netfs: fix reference leak",
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    "cveId": "CVE-2025-40007",
    "datePublished": "2025-10-20T15:26:53.880Z",
    "dateReserved": "2025-04-16T07:20:57.151Z",
    "dateUpdated": "2026-05-23T16:01:14.674Z",
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}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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