GHSA-GJ9W-7MFP-HC5M
Vulnerability from github – Published: 2026-09-16 12:30 – Updated: 2026-09-16 15:31In the Linux kernel, the following vulnerability has been resolved:
nvdimm/btt: reject an arena whose nfree is below the lane count
The BTT info block's nfree field, the number of reserve free blocks, is read from the medium without validation. btt_freelist_init() and btt_rtt_init() size the per-lane freelist[] and rtt[] arrays by nfree, but the I/O path indexes them by the lane from nd_region_acquire_lane(), which is bounded by nd_region->num_lanes (ND_MAX_LANES), not by nfree. A crafted or foreign arena whose nfree is below the lane count makes freelist[lane]/rtt[lane] run past the allocation: an out-of-bounds write.
btt.rst documents the nlanes = min(nfree, num_cpus) invariant, which the code does not currently honor: num_lanes is ND_MAX_LANES regardless of nfree. Reject an arena whose nfree is below num_lanes at discovery, before the per-lane arrays are allocated, enforcing that invariant.
{
"affected": [],
"aliases": [
"CVE-2026-89965"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-16T11:17:07Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnvdimm/btt: reject an arena whose nfree is below the lane count\n\nThe BTT info block\u0027s nfree field, the number of reserve free blocks, is\nread from the medium without validation. btt_freelist_init() and\nbtt_rtt_init() size the per-lane freelist[] and rtt[] arrays by nfree,\nbut the I/O path indexes them by the lane from nd_region_acquire_lane(),\nwhich is bounded by nd_region-\u003enum_lanes (ND_MAX_LANES), not by nfree.\nA crafted or foreign arena whose nfree is below the lane count makes\nfreelist[lane]/rtt[lane] run past the allocation: an out-of-bounds write.\n\nbtt.rst documents the nlanes = min(nfree, num_cpus) invariant, which the\ncode does not currently honor: num_lanes is ND_MAX_LANES regardless of\nnfree. Reject an arena whose nfree is below num_lanes at discovery,\nbefore the per-lane arrays are allocated, enforcing that invariant.",
"id": "GHSA-gj9w-7mfp-hc5m",
"modified": "2026-09-16T15:31:03Z",
"published": "2026-09-16T12:30:43Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89965"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/59d5cd1f42b4bab3609512c3cb3d3540d3d21da7"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6a1f2e5ed9267ca19187038ac635393c165213ac"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6b1faf1f099f7060b5f1f2f0d024132581f1726e"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6f79d1a5f2611a3d36e9312be5425cd9cb397c51"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9dfa11cef4750b67591307f2c62e47a23d60e4b7"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/eb491343d2d1784121ad9af91c25b338c28913c3"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f6c5313aae794ecca8f762c1a3493de5c266f120"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f9bf05c63b77d000e9c01f3e47af36973887d350"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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