{"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":"2026-09-14T12:00:29.988Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-09-14T12:00:29.988Z"},"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-rc1","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-rc1"}]}]}],"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"}}}}