fs/nfs/read: fix double-unlock bug in nfs_return_empty_folio()

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2025-38338
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-07-10 09:15:28 UTC
Updated2026-11-05 21:18:27 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: fs/nfs/read: fix double-unlock bug in nfs_return_empty_folio() Sometimes, when a file was read while it was being truncated by another NFS client, the kernel could deadlock because folio_unlock() was called twice, and the second call would XOR back the `PG_locked` flag. Most of the time (depending on the timing of the truncation), nobody notices the problem because folio_unlock() gets called three times, which flips `PG_locked` back off: 1. vfs_read, nfs_read_folio, ... nfs_read_add_folio, nfs_return_empty_folio 2. vfs_read, nfs_read_folio, ... netfs_read_collection, netfs_unlock_abandoned_read_pages 3. vfs_read, ... nfs_do_read_folio, nfs_read_add_folio, nfs_return_empty_folio The problem is that nfs_read_add_folio() is not supposed to unlock the folio if fscache is enabled, and a nfs_netfs_folio_unlock() check is missing in nfs_return_empty_folio(). Rarely this leads to a warning in netfs_read_collection(): ------------[ cut here ]------------ R=0000031c: folio 10 is not locked WARNING: CPU: 0 PID: 29 at fs/netfs/read_collect.c:133 netfs_read_collection+0x7c0/0xf00 [...] Workqueue: events_unbound netfs_read_collection_worker RIP: 0010:netfs_read_collection+0x7c0/0xf00 [...] Call Trace: <TASK> netfs_read_collection_worker+0x67/0x80 process_one_work+0x12e/0x2c0 worker_thread+0x295/0x3a0 Most of the time, however, processes just get stuck forever in folio_wait_bit_common(), waiting for `PG_locked` to disappear, which never happens because nobody is really holding the folio lock.

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-415

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 000dbe0bec058cbf2ca9e156e4a5584f5158b0f9 14f5549ad163be2c018abc1bb38370fff617a243 git Not specified
CNA Linux Linux affected 000dbe0bec058cbf2ca9e156e4a5584f5158b0f9 5bf0b9eeb0174686f22c2e5b8fb9f47ad25da6f5 git Not specified
CNA Linux Linux affected 000dbe0bec058cbf2ca9e156e4a5584f5158b0f9 1e93b61d3eaa14bfebcc2716ac09d43f3845d420 git Not specified
CNA Linux Linux affected 000dbe0bec058cbf2ca9e156e4a5584f5158b0f9 4c10fa44bc5f700e2ea21de2fbae520ba21f19d9 git Not specified
CNA Linux Linux affected 6.4 Not specified
CNA Linux Linux unaffected 6.4 semver Not specified
CNA Linux Linux unaffected 6.6.95 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.35 6.12.* semver Not specified
CNA Linux Linux unaffected 6.15.4 6.15.* semver Not specified
CNA Linux Linux unaffected 6.16 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/14f5549ad163be2c018abc1bb38370fff617a243 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/1e93b61d3eaa14bfebcc2716ac09d43f3845d420 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/4c10fa44bc5f700e2ea21de2fbae520ba21f19d9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/5bf0b9eeb0174686f22c2e5b8fb9f47ad25da6f5 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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