{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-89495", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.714Z", "datePublished": "2026-09-11T19:43:46.107Z", "dateUpdated": "2026-10-19T08:47:46.925Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:47:46.925Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nocfs2: bound namelen in dlm_migrate_request_handler\n\nPatch series \"ocfs2/dlm: bound peer-controlled lengths in the o2dlm\".\n\nThe o2dlm receive handlers trust u8 length and count fields from the wire\nwithout bounding them, so a node in a DLM domain can corrupt or panic any\nother node with a malformed message. Three defects:\n\n - dlm_migrate_request_handler() passes migrate->namelen unchecked to\n dlm_init_mle(), which memcpy()s it into the 32-byte mname[] of an\n o2dlm_mle slab object: a heap out-of-bounds write of up to ~215\n attacker-controlled bytes.\n\n - dlm_mig_lockres_handler() passes mres->lockname_len unchecked to\n dlm_init_lockres(), which memcpy()s it into the 32-byte o2dlm_lockname\n slab object: a heap out-of-bounds write of up to ~223 bytes.\n\n - the same handler trusts mres->num_locks without checking that the\n message is large enough to hold that many entries, so\n dlm_process_recovery_data() walks mres->ml[] past the kmalloc(data_len)\n copy and trips a BUG_ON (an out-of-bounds read ending in a panic).\n\nThe other o2dlm receive handlers already reject an oversized name; the\nmigration and recovery handlers have omitted it since the DLM was added\n(see the Fixes tags). Patch 1 bounds namelen; patch 2 validates\nlockname_len, num_locks, and the payload size. Conforming recovery and\nmigration traffic is unaffected.\n\no2net authenticates peers only by the DLM domain key, so any node that has\njoined the domain -- including a compromised or malicious member -- can\nsend these messages. There is no local trigger; the attacker must already\nbe a member of the cluster.\n\nEach sink was confirmed under KASAN with an out-of-tree module mirroring\nit exactly -- a kmem_cache/kmalloc of the real destination size, then the\nsame unclamped memcpy/loop: slab-out-of-bounds Write for the two writes,\nRead for the recovery walk, and a panic. A userspace AddressSanitizer\nbuild faults identically under -m32 and -m64. Scrubbed logs are available\non request.\n\nI reported this privately to security@kernel.org and the ocfs2 maintainers\non 2026-06-20; with no response after the standard embargo period I am\nposting the fix publicly. I have no embargo requirement.\n\n\nThis patch (of 2):\n\nA node receiving a DLM_MIGRATE_REQUEST message trusts the peer-supplied\nname length (migrate->namelen) without bounding it. dlm_init_mle() then\ncopies that many bytes into the fixed DLM_LOCKID_NAME_MAX-byte mname[]\narray of an o2dlm_mle slab object, so a malformed message from a cluster\npeer overflows the slab object by up to ~215 bytes: a heap out-of-bounds\nwrite of attacker-controlled data, reachable by any node in the domain.\n\nReject an oversized name, the way dlm_master_request_handler() and the\nother o2dlm receive handlers already do; the migration handler omits the\ncheck entirely. Conforming messages are unaffected." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - DLM_MIGRATE_REQUEST is received and dispatched by the ocfs2 o2net TCP cluster transport, so dlm_migrate_request_handler() is reached through network protocol messages from a peer node.\nAC:L - A cluster peer can send a crafted DLM_MIGRATE_REQUEST with attacker-chosen namelen; dlm_init_mle() then memcpy()s that length into the 32-byte mname[] with no race or other condition outside the attacker's control.\nPR:N - o2net gates peers by configured node IP, heartbeat, and the DLM domain key, with no user authentication or target-local privilege check before the handler runs, so exploitation needs no account on the victim.\nUI:N - Once the OCFS2/DLM domain is joined, exploitation is driven entirely by attacker-sent o2net messages and requires no victim user action such as mounting or opening a file.\nS:U - The heap overflow and resulting kernel impact remain within the same kernel and OCFS2 cluster-node security authority and do not cross a guest-to-host or IOMMU boundary.\nC:H - Unchecked namelen produces a heap out-of-bounds write of attacker-controlled bytes past the o2dlm_mle slab object and an out-of-bounds read of the source name buffer, which can disclose adjacent kernel memory.\nI:H - dlm_init_mle() memcpy()s up to 255 attacker-controlled bytes into the 32-byte mname[] of an o2dlm_mle slab object, overflowing the object by about 215 bytes and enabling overwrite of adjacent heap objects and kernel control-flow hijacking.\nA:H - The heap out-of-bounds write past the o2dlm_mle slab object can oops or panic the receiving node, fully denying availability." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ocfs2/dlm/dlmmaster.c" ], "versions": [ { "version": "6714d8e86bf443f6f7af50f9d432025649f091f5", "lessThan": "e1288865b8ceac0dcd1009ecba43de961f13d5bd", "status": "affected", "versionType": "git" }, { "version": "6714d8e86bf443f6f7af50f9d432025649f091f5", "lessThan": "aabc5d8388e6f8826345f0073455dbcaaaa6491d", "status": "affected", "versionType": "git" }, { "version": "6714d8e86bf443f6f7af50f9d432025649f091f5", "lessThan": "006c96ea488eca2ef5155ec76038e0a4dbf65f0a", "status": "affected", "versionType": "git" }, { "version": "6714d8e86bf443f6f7af50f9d432025649f091f5", "lessThan": "24989909d3413b44b104102caa6661b1e424ba0f", "status": "affected", "versionType": "git" }, { "version": "6714d8e86bf443f6f7af50f9d432025649f091f5", "lessThan": "f8658ee3327f73bd81c0bcd07cdeb5a8527fac98", "status": "affected", "versionType": "git" }, { "version": "6714d8e86bf443f6f7af50f9d432025649f091f5", "lessThan": "de10cd3b062a5235af754925fcf49beb5a1109d4", "status": "affected", "versionType": "git" }, { "version": "6714d8e86bf443f6f7af50f9d432025649f091f5", "lessThan": "2487bea2098322669f0563baff53e797486b823f", "status": "affected", "versionType": "git" }, { "version": "6714d8e86bf443f6f7af50f9d432025649f091f5", "lessThan": "ea5b5609305a8437bc955a0834a530c12246d78f", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ocfs2/dlm/dlmmaster.c" ], "versions": [ { "version": "2.6.16", "status": "affected" }, { "version": "0", "lessThan": "2.6.16", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.270", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.221", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.188", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.157", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.109", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.50", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.16", "versionEndExcluding": "5.10.270" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.16", "versionEndExcluding": "5.15.221" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.16", "versionEndExcluding": "6.1.188" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.16", "versionEndExcluding": "6.6.157" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.16", "versionEndExcluding": "6.12.109" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.16", "versionEndExcluding": "6.18.50" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.16", "versionEndExcluding": "7.2.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.16", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/e1288865b8ceac0dcd1009ecba43de961f13d5bd" }, { "url": "https://git.kernel.org/stable/c/aabc5d8388e6f8826345f0073455dbcaaaa6491d" }, { "url": "https://git.kernel.org/stable/c/006c96ea488eca2ef5155ec76038e0a4dbf65f0a" }, { "url": "https://git.kernel.org/stable/c/24989909d3413b44b104102caa6661b1e424ba0f" }, { "url": "https://git.kernel.org/stable/c/f8658ee3327f73bd81c0bcd07cdeb5a8527fac98" }, { "url": "https://git.kernel.org/stable/c/de10cd3b062a5235af754925fcf49beb5a1109d4" }, { "url": "https://git.kernel.org/stable/c/2487bea2098322669f0563baff53e797486b823f" }, { "url": "https://git.kernel.org/stable/c/ea5b5609305a8437bc955a0834a530c12246d78f" } ], "title": "ocfs2: bound namelen in dlm_migrate_request_handler", "x_generator": { "engine": "bippy-1.2.0" } } } }