{"id":"CVE-2026-68082","revision":"8aedad07334a42abb86eda1ea93743f7","records":[{"revision":"8aedad07334a42abb86eda1ea93743f7","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-68082","aliases":[],"title":"libceph: fix two unsafe bare decodes in decode_lockers()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nlibceph: fix two unsafe bare decodes in decode_lockers()\n\ndecode_lockers() in cls_lock_client.c contains two bare decode operations\nthat allow a malicious or compromised OSD to trigger slab-out-of-bounds\nreads:\n\n1. ceph_decode_32(p) at the num_lockers field has no preceding bounds\n check. ceph_start_decoding() accepts struct_len=0 as valid -- the\n internal ceph_decode_need(p, end, 0, bad) always passes -- so when an\n OSD sends struct_len=0, ceph_start_decoding() returns success with\n p == end. The immediately following bare ceph_decode_32(p) then reads\n 4 bytes past the validated buffer boundary. The garbage value is\n passed directly to kzalloc_objs() as the locker count.\n\n The sibling function decode_watchers() in osd_client.c already uses\n ceph_decode_32_safe() after its own ceph_start_decoding() call.\n decode_lockers() was the only site using the bare variant.\n\n2. ceph_decode_8(p) after the decode_locker() loop has no preceding\n bounds check. If an OSD crafts num_lockers such that the loop\n advances p exactly to end, the subsequent bare ceph_decode_8(p) reads\n one byte past the validated buffer boundary. The result is passed\n directly into *type, which is used as a lock type discriminator by\n callers, giving an OSD-controlled one-byte OOB read with direct\n influence over the lock type field.\n\nFix both by replacing bare operations with their safe variants:\n ceph_decode_32(p) -> ceph_decode_32_safe(p, end, *num_lockers,\n err_inval)\n ceph_decode_8(p) -> ceph_decode_8_safe(p, end, *type,\n err_free_lockers)\n\nThe goto targets differ intentionally:\n err_inval: is a new label returning -EINVAL directly. It is used for\n the pre-allocation failure path where *lockers is not yet allocated\n and must not be passed to ceph_free_lockers().\n\n err_free_lockers: is the existing label. It is used for the\n post-allocation failure path where *lockers is allocated and must\n be freed.\n\nret is set to -EINVAL before ceph_decode_8_safe() so that\nerr_free_lockers returns the correct error code on bounds violation.\nWithout this, err_free_lockers would return a stale ret value (0 from\nthe successful decode_locker() loop), silently swallowing the error.\n\n-EINVAL is correct for both failure paths. The data received from the\nOSD is structurally malformed. -ENOMEM would misrepresent the failure\nclass to callers and to stable@ backporters triaging error paths.\n\nAttacker model: a malicious or compromised OSD in a multi-tenant Ceph\ndeployment can trigger this against any kernel client that issues the\nlock.get_info class method (e.g. during RBD exclusive lock acquisition).\n\n[ idryomov: trim changelog, formatting ]","state":0,"publishedAt":"2026-08-08T09:17:45.394+00:00","modifiedAt":"2026-10-19T20:48:44.16+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"net/ceph/cls_lock_client.c\"\n ],\n \"versions\": [\n {\n \"version\": \"d4ed4a530562881cc5225050e42d96034f405aae\",\n \"lessThan\": \"c8ade01170a27d8ede0d761c255268af81e417f8\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"d4ed4a530562881cc5225050e42d96034f405aae\",\n \"lessThan\": \"001835c599899ef1bd3506a815110a6374451554\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"d4ed4a530562881cc5225050e42d96034f405aae\",\n \"lessThan\": \"7c422364acd93d7da1dfc27d6b54635a269653a1\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"d4ed4a530562881cc5225050e42d96034f405aae\",\n \"lessThan\": \"02430f6f729b297e803d0605871f0a670b4eafd6\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"d4ed4a530562881cc5225050e42d96034f405aae\",\n \"lessThan\": \"57ba829804fe6d34bbac3b826c4b15c1caa54862\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"d4ed4a530562881cc5225050e42d96034f405aae\",\n \"lessThan\": \"89df5d71f83f8e2781286798fd8ae5e42cf5f1a7\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"d4ed4a530562881cc5225050e42d96034f405aae\",\n \"lessThan\": \"a54be593d0b749161b08a1e56189b2cb9114267a\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"d4ed4a530562881cc5225050e42d96034f405aae\",\n \"lessThan\": \"a109a556115271ca7896dcda7b4b7e45e156c227\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"net/ceph/cls_lock_client.c\"\n ],\n \"versions\": [\n {\n \"version\": \"4.9\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"4.9\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.10.266\",\n \"lessThanOrEqual\": \"5.10.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.15.217\",\n \"lessThanOrEqual\": \"5.15.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.1.184\",\n \"lessThanOrEqual\": \"6.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.153\",\n \"lessThanOrEqual\": \"6.6.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.105\",\n \"lessThanOrEqual\": \"6.12.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.18.46\",\n \"lessThanOrEqual\": \"6.18.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.1.6\",\n \"lessThanOrEqual\": \"7.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.2\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8,"severity":"CRITICAL"}],"references":["https://git.kernel.org/stable/c/c8ade01170a27d8ede0d761c255268af81e417f8","https://git.kernel.org/stable/c/001835c599899ef1bd3506a815110a6374451554","https://git.kernel.org/stable/c/7c422364acd93d7da1dfc27d6b54635a269653a1","https://git.kernel.org/stable/c/02430f6f729b297e803d0605871f0a670b4eafd6","https://git.kernel.org/stable/c/57ba829804fe6d34bbac3b826c4b15c1caa54862","https://git.kernel.org/stable/c/89df5d71f83f8e2781286798fd8ae5e42cf5f1a7","https://git.kernel.org/stable/c/a54be593d0b749161b08a1e56189b2cb9114267a","https://git.kernel.org/stable/c/a109a556115271ca7896dcda7b4b7e45e156c227"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-68082","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-68082","identifiers":["CVE-2026-68082"]},"retained":false,"historicalAffected":[]}],"coverage":[]}