{"id":"DEBIAN-CVE-2025-38338","details":"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:   \u003cTASK\u003e   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.","modified":"2026-08-27T23:05:21.824374879Z","published":"2025-07-10T09:15:28.510Z","upstream":["CVE-2025-38338"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2025-38338"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.35-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2025-38338.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.35-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2025-38338.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}