CVE-2025-38338
fs/nfs/read: fix double-unlock bug in nfs_return_empty_folio()
In 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.
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| Linux Linux |
≥ 000dbe0bec058cbf2ca9e156e4a5584f5158b0f9; < 14f5549ad163be2c018abc1bb38370fff617a243 (affected, git) ≥ 000dbe0bec058cbf2ca9e156e4a5584f5158b0f9; < 5bf0b9eeb0174686f22c2e5b8fb9f47ad25da6f5 (affected, git) ≥ 000dbe0bec058cbf2ca9e156e4a5584f5158b0f9; < 1e93b61d3eaa14bfebcc2716ac09d43f3845d420 (affected, git) ≥ 000dbe0bec058cbf2ca9e156e4a5584f5158b0f9; < 4c10fa44bc5f700e2ea21de2fbae520ba21f19d9 (affected, git) Other versions: unaffected |
CNA: Linux |
| Linux Linux |
6.4 (affected) ≥ 0; < 6.4 (unaffected, semver) ≥ 6.6.95; ≤ 6.6.* (unaffected, semver) ≥ 6.12.35; ≤ 6.12.* (unaffected, semver) ≥ 6.15.4; ≤ 6.15.* (unaffected, semver) ≥ 6.16; ≤ * (unaffected, original_commit_for_fix) Other versions: affected |
CNA: Linux |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
No CVSS assessment reported. An unscored record is not a low-severity determination.
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://git.kernel.org/stable/c/14f5549ad163be2c018abc1bb38370fff617a243CNA: Linux
- https://git.kernel.org/stable/c/5bf0b9eeb0174686f22c2e5b8fb9f47ad25da6f5CNA: Linux
- https://git.kernel.org/stable/c/1e93b61d3eaa14bfebcc2716ac09d43f3845d420CNA: Linux
- https://git.kernel.org/stable/c/4c10fa44bc5f700e2ea21de2fbae520ba21f19d9CNA: Linux
For agents and automation
Read public disclosures for free as Markdown or JSON. Compatible browsers also expose native WebMCP tools to search disclosures, read this page, and discover API access.
Use the ontology-linked Cyber API with x402 pay per request, or a Y2 Pro or Elite API key with the intel:cyber scope.
Endpoints and access details
https://api.y2.dev/api/v2/cyber/cveshttps://api.y2.dev/api/v2/cyber/cves/{cveId}
A workspace owner or admin can create a Pro or Elite API key. Send Authorization: Bearer <Y2_API_KEY> from your trusted agent runtime.
For x402, omit Authorization and read the HTTP 402 payment challenge before signing a retry. Public browser tools do not make payments.