{"id":"CVE-2025-38338","summary":"fs/nfs/read: fix double-unlock bug in nfs_return_empty_folio()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nfs/nfs/read: fix double-unlock bug in nfs_return_empty_folio()\n\nSometimes, when a file was read while it was being truncated by\nanother NFS client, the kernel could deadlock because folio_unlock()\nwas called twice, and the second call would XOR back the `PG_locked`\nflag.\n\nMost of the time (depending on the timing of the truncation), nobody\nnotices the problem because folio_unlock() gets called three times,\nwhich flips `PG_locked` back off:\n\n 1. vfs_read, nfs_read_folio, ... nfs_read_add_folio,\n    nfs_return_empty_folio\n 2. vfs_read, nfs_read_folio, ... netfs_read_collection,\n    netfs_unlock_abandoned_read_pages\n 3. vfs_read, ... nfs_do_read_folio, nfs_read_add_folio,\n    nfs_return_empty_folio\n\nThe problem is that nfs_read_add_folio() is not supposed to unlock the\nfolio if fscache is enabled, and a nfs_netfs_folio_unlock() check is\nmissing in nfs_return_empty_folio().\n\nRarely this leads to a warning in netfs_read_collection():\n\n ------------[ cut here ]------------\n R=0000031c: folio 10 is not locked\n WARNING: CPU: 0 PID: 29 at fs/netfs/read_collect.c:133 netfs_read_collection+0x7c0/0xf00\n [...]\n Workqueue: events_unbound netfs_read_collection_worker\n RIP: 0010:netfs_read_collection+0x7c0/0xf00\n [...]\n Call Trace:\n  \u003cTASK\u003e\n  netfs_read_collection_worker+0x67/0x80\n  process_one_work+0x12e/0x2c0\n  worker_thread+0x295/0x3a0\n\nMost of the time, however, processes just get stuck forever in\nfolio_wait_bit_common(), waiting for `PG_locked` to disappear, which\nnever happens because nobody is really holding the folio lock.","modified":"2026-04-15T23:59:23.042259598Z","published":"2025-07-10T08:15:09.022Z","related":["SUSE-SU-2025:02853-1","SUSE-SU-2025:02923-1","SUSE-SU-2025:02969-1","SUSE-SU-2025:02996-1","SUSE-SU-2025:02997-1","SUSE-SU-2025:03011-1","SUSE-SU-2025:03023-1","SUSE-SU-2025:20577-1","SUSE-SU-2025:20586-1","SUSE-SU-2025:20601-1","SUSE-SU-2025:20602-1","SUSE-SU-2025:21074-1","SUSE-SU-2025:21139-1","SUSE-SU-2025:21179-1","openSUSE-SU-2025:20081-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/38xxx/CVE-2025-38338.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/14f5549ad163be2c018abc1bb38370fff617a243"},{"type":"WEB","url":"https://git.kernel.org/stable/c/1e93b61d3eaa14bfebcc2716ac09d43f3845d420"},{"type":"WEB","url":"https://git.kernel.org/stable/c/4c10fa44bc5f700e2ea21de2fbae520ba21f19d9"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5bf0b9eeb0174686f22c2e5b8fb9f47ad25da6f5"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/38xxx/CVE-2025-38338.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-38338"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"000dbe0bec058cbf2ca9e156e4a5584f5158b0f9"},{"fixed":"14f5549ad163be2c018abc1bb38370fff617a243"},{"fixed":"5bf0b9eeb0174686f22c2e5b8fb9f47ad25da6f5"},{"fixed":"1e93b61d3eaa14bfebcc2716ac09d43f3845d420"},{"fixed":"4c10fa44bc5f700e2ea21de2fbae520ba21f19d9"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-38338.json"}}],"schema_version":"1.7.5"}