{"id":"CVE-2026-43071","revision":"cd8258a7a8e043cc97fe6979a1cfff49","records":[{"revision":"cd8258a7a8e043cc97fe6979a1cfff49","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-43071","aliases":[],"title":"dcache: Limit the minimal number of bucket to two","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ndcache: Limit the minimal number of bucket to two\n\nThere is an OOB read problem on dentry_hashtable when user sets\n'dhash_entries=1':\n  BUG: unable to handle page fault for address: ffff888b30b774b0\n  #PF: supervisor read access in kernel mode\n  #PF: error_code(0x0000) - not-present page\n  Oops: Oops: 0000 [#1] SMP PTI\n  RIP: 0010:__d_lookup+0x56/0x120\n   Call Trace:\n    d_lookup.cold+0x16/0x5d\n    lookup_dcache+0x27/0xf0\n    lookup_one_qstr_excl+0x2a/0x180\n    start_dirop+0x55/0xa0\n    simple_start_creating+0x8d/0xa0\n    debugfs_start_creating+0x8c/0x180\n    debugfs_create_dir+0x1d/0x1c0\n    pinctrl_init+0x6d/0x140\n    do_one_initcall+0x6d/0x3d0\n    kernel_init_freeable+0x39f/0x460\n    kernel_init+0x2a/0x260\n\nThere will be only one bucket in dentry_hashtable when dhash_entries is\nset as one, and d_hash_shift is calculated as 32 by dcache_init(). Then,\nfollowing process will access more than one buckets(which memory region\nis not allocated) in dentry_hashtable:\n d_lookup\n  b = d_hash(hash)\n    dentry_hashtable + ((u32)hashlen >> d_hash_shift)\n    // The C standard defines the behavior of right shift amounts\n    // exceeding the bit width of the operand as undefined. The\n    // result of '(u32)hashlen >> d_hash_shift' becomes 'hashlen',\n    // so 'b' will point to an unallocated memory region.\n  hlist_bl_for_each_entry_rcu(b)\n   hlist_bl_first_rcu(head)\n    h->first  // read OOB!\n\nFix it by limiting the minimal number of dentry_hashtable bucket to two,\nso that 'd_hash_shift' won't exceeds the bit width of type u32.","state":0,"publishedAt":"2026-05-05T15:29:28.081+00:00","modifiedAt":"2026-10-19T19:06:12.548+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                        \"fs/dcache.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"99d263d4c5b2f541dfacb5391e22e8c91ea982a6\",\n                            \"lessThan\": \"45b06bb5ea96f75ad81d7ef446f832ea6b0026fe\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"99d263d4c5b2f541dfacb5391e22e8c91ea982a6\",\n                            \"lessThan\": \"426ef05e82ee52c8d0e95fc0808b7383d8352d73\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"99d263d4c5b2f541dfacb5391e22e8c91ea982a6\",\n                            \"lessThan\": \"ddd57ebce245f9c7e2f6902a6c087d6186d2385d\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"99d263d4c5b2f541dfacb5391e22e8c91ea982a6\",\n                            \"lessThan\": \"755b40903eff563768d4d96fd4ef51ec48adde3b\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"99d263d4c5b2f541dfacb5391e22e8c91ea982a6\",\n                            \"lessThan\": \"5718df131ab78897a9dd1f2e71c3ba732d4392af\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"99d263d4c5b2f541dfacb5391e22e8c91ea982a6\",\n                            \"lessThan\": \"277cedabb0ab86baae83fa58218be13c6d3e5526\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"99d263d4c5b2f541dfacb5391e22e8c91ea982a6\",\n                            \"lessThan\": \"f08fe8891c3eeb63b73f9f1f6d97aa629c821579\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"d4c96061fddd129778ce8b70fb093aa532f422d0\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"be2378cbffe50ce0161f0fdee914adee98af53dc\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"a8be8af18485f9fade90e1743d940252a39eec84\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"b5cf3193759f7cd1cfbeef11f5cf067bbce22e55\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"3.10.55\",\n                            \"lessThan\": \"3.11\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"3.12.29\",\n                            \"lessThan\": \"3.13\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"3.14.19\",\n                            \"lessThan\": \"3.15\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"3.16.3\",\n                            \"lessThan\": \"3.17\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\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                        \"fs/dcache.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"3.17\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"3.17\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.1.175\",\n                            \"lessThanOrEqual\": \"6.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.136\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.83\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.24\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.19.14\",\n                            \"lessThanOrEqual\": \"6.19.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.0.1\",\n                            \"lessThanOrEqual\": \"7.0.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.1\",\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:N/A:H","score":9.1,"severity":"CRITICAL"}],"references":["https://git.kernel.org/stable/c/45b06bb5ea96f75ad81d7ef446f832ea6b0026fe","https://git.kernel.org/stable/c/426ef05e82ee52c8d0e95fc0808b7383d8352d73","https://git.kernel.org/stable/c/ddd57ebce245f9c7e2f6902a6c087d6186d2385d","https://git.kernel.org/stable/c/755b40903eff563768d4d96fd4ef51ec48adde3b","https://git.kernel.org/stable/c/5718df131ab78897a9dd1f2e71c3ba732d4392af","https://git.kernel.org/stable/c/277cedabb0ab86baae83fa58218be13c6d3e5526","https://git.kernel.org/stable/c/f08fe8891c3eeb63b73f9f1f6d97aa629c821579"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-43071","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-43071","identifiers":["CVE-2026-43071"]},"retained":false,"historicalAffected":[]}],"coverage":[]}