GHSA-F2VV-WRGM-2RRJ
Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-13 09:32In the Linux kernel, the following vulnerability has been resolved:
nfsd: close shrinker/GC/fsnotify vs per-net shutdown race in filecache
The shrinker, GC worker, and fsnotify/lease callbacks can unhash an nfsd_file from the rhashtable and then call nfsd_file_dispose_list_delayed() to move it to the per-net dispose list. If nfsd_file_cache_shutdown_net() runs concurrently, its rhashtable walk misses the already-unhashed file, and its drain of the per-net dispose list can run before the file has been queued. The file then sits on the per-net list with no thread to drain it, leaking both the file and its associated state.
The GC worker and shrinker already hold nfsd_gc_lock while walking the LRU, but in the original code they release it before calling nfsd_file_dispose_list_delayed(). The fsnotify/lease path (nfsd_file_close_inode) has no synchronization at all.
Fix this by:
-
Widening nfsd_gc_lock in both nfsd_file_gc() and nfsd_file_lru_scan() to cover the nfsd_file_dispose_list_delayed() call.
-
Wrapping nfsd_file_close_inode() in nfsd_gc_lock so that all three callers of nfsd_file_dispose_list_delayed() hold the lock.
-
Adding a spin_lock/unlock(nfsd_gc_lock) barrier in nfsd_file_cache_shutdown_net() after the purge, so that any in-progress disposal has fully completed before the per-net list is drained.
All operations inside the lock are non-sleeping (rhashtable lookups, atomic bit/refcount ops, list moves, svc_wake_up), so the spinlock is appropriate.
{
"affected": [],
"aliases": [
"CVE-2026-89667"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-11T20:19:53Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: close shrinker/GC/fsnotify vs per-net shutdown race in filecache\n\nThe shrinker, GC worker, and fsnotify/lease callbacks can unhash an\nnfsd_file from the rhashtable and then call\nnfsd_file_dispose_list_delayed() to move it to the per-net dispose list.\nIf nfsd_file_cache_shutdown_net() runs concurrently, its rhashtable walk\nmisses the already-unhashed file, and its drain of the per-net dispose\nlist can run before the file has been queued. The file then sits on\nthe per-net list with no thread to drain it, leaking both the file and\nits associated state.\n\nThe GC worker and shrinker already hold nfsd_gc_lock while walking the\nLRU, but in the original code they release it before calling\nnfsd_file_dispose_list_delayed(). The fsnotify/lease path\n(nfsd_file_close_inode) has no synchronization at all.\n\nFix this by:\n\n 1. Widening nfsd_gc_lock in both nfsd_file_gc() and nfsd_file_lru_scan()\n to cover the nfsd_file_dispose_list_delayed() call.\n\n 2. Wrapping nfsd_file_close_inode() in nfsd_gc_lock so that all three\n callers of nfsd_file_dispose_list_delayed() hold the lock.\n\n 3. Adding a spin_lock/unlock(nfsd_gc_lock) barrier in\n nfsd_file_cache_shutdown_net() after the purge, so that any\n in-progress disposal has fully completed before the per-net list\n is drained.\n\nAll operations inside the lock are non-sleeping (rhashtable lookups,\natomic bit/refcount ops, list moves, svc_wake_up), so the spinlock is\nappropriate.",
"id": "GHSA-f2vv-wrgm-2rrj",
"modified": "2026-09-13T09:32:27Z",
"published": "2026-09-11T21:31:35Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89667"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/08af9593e2b472fd98c00faf1bf03bdbb7203477"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/40162cfea79b9510380decfdd1795b754dc9f972"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6d6b9f6a75c3767250e9c23ace4e384ab8f7843e"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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