CVE-2025-38338

HIGH EPSS 4.8%
Published Jul 10, 202511mo ago · Modified Jun 17, 20262w ago
7.8 CVSS 3.1
High
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Published Jul 10, 2025 11mo ago
Last Modified Jun 17, 2026 2w ago

Description

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.

CVSS Details

Base Score
7.8
Exploitability
1.8
Impact
5.9
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack Vector Local
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality High
Integrity High
Availability High

Threat Intelligence

EPSS Exploit Probability
4.8% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-415

Affected Products 3

VendorProductVersionRange
linuxlinux_kernel*≥6.4  –  <6.6.95
linuxlinux_kernel*≥6.7  –  <6.12.35
linuxlinux_kernel*≥6.13  –  <6.15.4

References 4

  • git.kernel.org https://git.kernel.org/stable/c/14f5549ad163be2c018abc1bb38370fff617a243
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/1e93b61d3eaa14bfebcc2716ac09d43f3845d420
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/4c10fa44bc5f700e2ea21de2fbae520ba21f19d9
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/5bf0b9eeb0174686f22c2e5b8fb9f47ad25da6f5
    Patch

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/14f5549ad163be2c018abc1bb38370fff617a243
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/1e93b61d3eaa14bfebcc2716ac09d43f3845d420
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/4c10fa44bc5f700e2ea21de2fbae520ba21f19d9
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/5bf0b9eeb0174686f22c2e5b8fb9f47ad25da6f5
    Patch