nfsd: provide locking for v4_end_grace

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Summary

CVECVE-2026-22980
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-01-23 16:15:54 UTC
Updated2026-07-14 13:18:21 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from [email protected]

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

Problem Types: CWE-416

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 ca97360860eb02e3ae4ba42c19b439a0fcecbf06 git Not specified
CNA Linux Linux affected 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 e8bfa2401d4c51eca6e48e9b33c798828ca9df61 git Not specified
CNA Linux Linux affected 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 34eb22836e0cdba093baac66599d68c4cd245a9d git Not specified
CNA Linux Linux affected 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 06600719d0f7a723811c45e4d51f5b742f345309 git Not specified
CNA Linux Linux affected 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 ba4811c8b433bfa681729ca42cc62b6034f223b0 git Not specified
CNA Linux Linux affected 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 53f07d095e7e680c5e4569a55a019f2c0348cdc6 git Not specified
CNA Linux Linux affected 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 2857bd59feb63fcf40fe4baf55401baea6b4feb4 git Not specified
CNA Linux Linux affected 3.18 Not specified
CNA Linux Linux unaffected 3.18 semver Not specified
CNA Linux Linux unaffected 5.10.248 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.198 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.161 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.121 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.66 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.6 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19 * original_commit_for_fix Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/e8bfa2401d4c51eca6e48e9b33c798828ca9df61 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/ca97360860eb02e3ae4ba42c19b439a0fcecbf06 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/ba4811c8b433bfa681729ca42cc62b6034f223b0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/06600719d0f7a723811c45e4d51f5b742f345309 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/2857bd59feb63fcf40fe4baf55401baea6b4feb4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
cert-portal.siemens.com/productcert/html/ssa-019113.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
git.kernel.org/stable/c/34eb22836e0cdba093baac66599d68c4cd245a9d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/53f07d095e7e680c5e4569a55a019f2c0348cdc6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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