{"id":"CVE-2026-89965","summary":"nvdimm/btt: reject an arena whose nfree is below the lane count","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's 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.","modified":"2026-09-17T03:47:28.583055501Z","published":"2026-09-16T10:32:46.769Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89965.json","cna_assigner":"Linux"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"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"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89965.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89965"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"5212e11fde4d40fa627668b4f2222d20db488f71"},{"fixed":"eb491343d2d1784121ad9af91c25b338c28913c3"},{"fixed":"59d5cd1f42b4bab3609512c3cb3d3540d3d21da7"},{"fixed":"f6c5313aae794ecca8f762c1a3493de5c266f120"},{"fixed":"f9bf05c63b77d000e9c01f3e47af36973887d350"},{"fixed":"6f79d1a5f2611a3d36e9312be5425cd9cb397c51"},{"fixed":"6b1faf1f099f7060b5f1f2f0d024132581f1726e"},{"fixed":"9dfa11cef4750b67591307f2c62e47a23d60e4b7"},{"fixed":"6a1f2e5ed9267ca19187038ac635393c165213ac"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89965.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.2.0"},{"fixed":"5.10.270"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.221"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.188"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.157"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.110"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.51"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89965.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}