GHSA-8W8J-GJ8P-WM2M
Vulnerability from github – Published: 2026-09-24 18:31 – Updated: 2026-09-24 18:31In the Linux kernel, the following vulnerability has been resolved:
nfsd: guard nfsd_serv deref in nfsd_file_net_dispose
nfsd_file_net_dispose() is the consumer side of l->freeme: the nfsd service thread loop calls it to drain entries that the filecache garbage collector and shrinker append via nfsd_file_dispose_list_delayed(). During per-net teardown, nn->nfsd_serv is cleared before the filecache laundrette is shut down, so the service thread can still run a dispose pass that finds more than eight entries on l->freeme and dereferences a NULL svc_serv:
nfsd service thread loop
nfsd_file_net_dispose(nn)
if (!list_empty(&l->freeme)) {
...
svc_wake_up(nn->nfsd_serv); /* nn->nfsd_serv == NULL */
}
The sibling helper nfsd_file_dispose_list_delayed() already documents this ordering and caches nn->nfsd_serv into a local before testing it for NULL. nfsd_file_net_dispose() was introduced with the same raw svc_wake_up(nn->nfsd_serv) call and never picked up the guard.
Fix by loading nn->nfsd_serv into a local svc_serv pointer and only calling svc_wake_up() when it is non-NULL, matching the pattern in nfsd_file_dispose_list_delayed().
{
"affected": [],
"aliases": [
"CVE-2026-93212"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-24T16:17:16Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: guard nfsd_serv deref in nfsd_file_net_dispose\n\nnfsd_file_net_dispose() is the consumer side of l-\u003efreeme: the nfsd\nservice thread loop calls it to drain entries that the filecache\ngarbage collector and shrinker append via\nnfsd_file_dispose_list_delayed(). During per-net teardown,\nnn-\u003enfsd_serv is cleared before the filecache laundrette is shut\ndown, so the service thread can still run a dispose pass that finds\nmore than eight entries on l-\u003efreeme and dereferences a NULL\nsvc_serv:\n\n nfsd service thread loop\n nfsd_file_net_dispose(nn)\n if (!list_empty(\u0026l-\u003efreeme)) {\n ...\n svc_wake_up(nn-\u003enfsd_serv); /* nn-\u003enfsd_serv == NULL */\n }\n\nThe sibling helper nfsd_file_dispose_list_delayed() already documents\nthis ordering and caches nn-\u003enfsd_serv into a local before testing it\nfor NULL. nfsd_file_net_dispose() was introduced with the same raw\nsvc_wake_up(nn-\u003enfsd_serv) call and never picked up the guard.\n\nFix by loading nn-\u003enfsd_serv into a local svc_serv pointer and only\ncalling svc_wake_up() when it is non-NULL, matching the pattern in\nnfsd_file_dispose_list_delayed().",
"id": "GHSA-8w8j-gj8p-wm2m",
"modified": "2026-09-24T18:31:22Z",
"published": "2026-09-24T18:31:22Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-93212"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/59baf45a06435194005fc5fa9a42d89f77a30432"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/766170b4fd2daaf5c4d6735560101474e18edab6"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9f1ddfc8cb9076592401a611eb3a44d36186d014"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f4776c1c4b38fbc459420321c8ece87d0f7f95fb"
}
],
"schema_version": "1.4.0",
"severity": []
}
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