GHSA-5PV5-P9Q3-RVV6
Vulnerability from github – Published: 2026-09-17 18:31 – Updated: 2026-10-30 15:33In the Linux kernel, the following vulnerability has been resolved:
NFSv4/flexfiles: fix NULL dereference for NFSv4.0 data servers
flexfiles accepts NFSv4.0 data servers, but two NFSv4 code paths assume the data server client has a session. Unlike NFSv4.1+, an NFSv4.0 client has no session (clp->cl_session is NULL; it uses clp->cl_slot_tbl), so I/O to a v4.0 flexfiles DS oopses:
-
nfs4_init_ds_session() dereferences clp->cl_session->session_state while seeding the DS lease. It also only seeds cl_lease_time when NFS4_SESSION_INITING is set; without a session that never happens, so cl_lease_time stays 0 and nfs4_renew_state() busy-loops, requeuing every 5 seconds. Seed the lease whenever there is no session and return before touching session state.
-
ff_layout_async_handle_error_v4() dereferences clp->cl_session->fc_slot_table on every DS I/O error. Fall back to the v4.0 transport slot table (clp->cl_slot_tbl) when there is no session.
{
"affected": [],
"aliases": [
"CVE-2026-90149"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-17T17:17:07Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSv4/flexfiles: fix NULL dereference for NFSv4.0 data servers\n\nflexfiles accepts NFSv4.0 data servers, but two NFSv4 code paths assume\nthe data server client has a session. Unlike NFSv4.1+, an NFSv4.0 client\nhas no session (clp-\u003ecl_session is NULL; it uses clp-\u003ecl_slot_tbl), so\nI/O to a v4.0 flexfiles DS oopses:\n\n - nfs4_init_ds_session() dereferences clp-\u003ecl_session-\u003esession_state\n while seeding the DS lease. It also only seeds cl_lease_time when\n NFS4_SESSION_INITING is set; without a session that never happens, so\n cl_lease_time stays 0 and nfs4_renew_state() busy-loops, requeuing\n every 5 seconds. Seed the lease whenever there is no session and\n return before touching session state.\n\n - ff_layout_async_handle_error_v4() dereferences\n clp-\u003ecl_session-\u003efc_slot_table on every DS I/O error. Fall back to the\n v4.0 transport slot table (clp-\u003ecl_slot_tbl) when there is no session.",
"id": "GHSA-5pv5-p9q3-rvv6",
"modified": "2026-10-30T15:33:32Z",
"published": "2026-09-17T18:31:52Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90149"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/163c16e01f53fc8eb8d0f3484ae6c382265ecbbd"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2b03ebbf8d5e8f6af4ecd6c65375232dd1ec32cc"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/336b6da10021c69a8f273bbacdf7432fdc89a06f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/436a214514e24103159aea455147d58b44a8a585"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5527af72b0100c94287bfec901b6313eeac567ca"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e55d7fec8a9290f73032ee34c35dd68532809633"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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