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CVE-2026-22980

nfsd: provide locking for v4_end_grace

HIGH 7.8

At a glance

Source
NVD
EPSS
EPSS 0.15 % · percentile 4 ()
State
PUBLISHED
Published
Updated
Assigner
Linux
NVD status
Modified

Description

In the Linux kernel, the following vulnerability has been resolved: nfsd: provide locking for v4_end_grace Writing to v4_end_grace can race with server shutdown and result in memory being accessed after it was freed - reclaim_str_hashtbl in particularly. We cannot hold nfsd_mutex across the nfsd4_end_grace() call as that is held while client_tracking_op->init() is called and that can wait for an upcall to nfsdcltrack which can write to v4_end_grace, resulting in a deadlock. nfsd4_end_grace() is also called by the landromat work queue and this doesn't require locking as server shutdown will stop the work and wait for it before freeing anything that nfsd4_end_grace() might access. However, we must be sure that writing to v4_end_grace doesn't restart the work item after shutdown has already waited for it. For this we add a new flag protected with nn->client_lock. It is set only while it is safe to make client tracking calls, and v4_end_grace only schedules work while the flag is set with the spinlock held. So this patch adds a nfsd_net field "client_tracking_active" which is set as described. Another field "grace_end_forced", is set when v4_end_grace is written. After this is set, and providing client_tracking_active is set, the laundromat is scheduled. This "grace_end_forced" field bypasses other checks for whether the grace period has finished. This resolves a race which can result in use-after-free.

Weaknesses (CWE)

References

Scores

VersionScoreVectorScored by
CVSS 3.1HIGH 7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HLinux
CVSS 3.1HIGH 7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HNVD · 416baaa9-dc9f-4396-8d5f-8c081fb06d67 (Secondary)
CVSS 3.1HIGH 7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HNVD · nvd@nist.gov (Primary)

European references

CERT-FR advisories

Affected configurations (NVD CPE)

Affected products

ProductVersions
Linux · Linuxaffected 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 < ca97360860eb02e3ae4ba42c19b439a0fcecbf06 ; affected 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 < e8bfa2401d4c51eca6e48e9b33c798828ca9df61 ; affected 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 < 34eb22836e0cdba093baac66599d68c4cd245a9d ; affected 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 < 06600719d0f7a723811c45e4d51f5b742f345309 ; affected 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 < ba4811c8b433bfa681729ca42cc62b6034f223b0 ; affected 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 < 53f07d095e7e680c5e4569a55a019f2c0348cdc6
Linux · Linuxaffected 3.18 ; unaffected 0 < 3.18 ; unaffected 5.10.248 ≤ 5.10.* ; unaffected 5.15.198 ≤ 5.15.* ; unaffected 6.1.161 ≤ 6.1.* ; unaffected 6.6.121 ≤ 6.6.*

Sources

SourceLicence
CVE List (CVEProject cvelistV5)CVE Program Terms of Use
EPSS (FIRST.org)FIRST — attribution requested
ENISA EUVDENISA — reproduction authorised, source acknowledged
CERT-FR (ANSSI)Licence Ouverte / Etalab 2.0
NVD (NIST) via fkie-cad/nvd-json-data-feedsPublic domain — this product uses data from the NVD API but is not endorsed or certified by the NVD