dcache: Limit the minimal number of bucket to two_CVE-2026-43071

{
    "lastseen": "",
    "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.",
    "published": "2026-05-05T15:29:28.081Z",
    "modified": "2026-05-08T12:40:21.054Z",
    "type": "cve",
    "title": "dcache: Limit the minimal number of bucket to two",
    "source": "Linux",
    "references": "https://git.kernel.org/stable/c/426ef05e82ee52c8d0e95fc0808b7383d8352d73\nhttps://git.kernel.org/stable/c/ddd57ebce245f9c7e2f6902a6c087d6186d2385d\nhttps://git.kernel.org/stable/c/755b40903eff563768d4d96fd4ef51ec48adde3b\nhttps://git.kernel.org/stable/c/5718df131ab78897a9dd1f2e71c3ba732d4392af\nhttps://git.kernel.org/stable/c/277cedabb0ab86baae83fa58218be13c6d3e5526\nhttps://git.kernel.org/stable/c/f08fe8891c3eeb63b73f9f1f6d97aa629c821579",
    "id": "CVE-2026-43071",
    "bulletinFamily": "",
    "cwe": null,
    "cvelist": null,
    "sourceData": "Linux Linux 99d263d4c5b2f541dfacb5391e22e8c91ea982a6\nLinux Linux 99d263d4c5b2f541dfacb5391e22e8c91ea982a6\nLinux Linux 99d263d4c5b2f541dfacb5391e22e8c91ea982a6\nLinux Linux 99d263d4c5b2f541dfacb5391e22e8c91ea982a6\nLinux Linux 99d263d4c5b2f541dfacb5391e22e8c91ea982a6\nLinux Linux 99d263d4c5b2f541dfacb5391e22e8c91ea982a6\nLinux Linux d4c96061fddd129778ce8b70fb093aa532f422d0\nLinux Linux be2378cbffe50ce0161f0fdee914adee98af53dc\nLinux Linux a8be8af18485f9fade90e1743d940252a39eec84\nLinux Linux b5cf3193759f7cd1cfbeef11f5cf067bbce22e55\nLinux Linux 3.17",
    "sourceHref": "",
    "cvss": {
        "score": 9.1,
        "severity": "CRITICAL",
        "vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
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    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "Linux",
    "version": "99d263d4c5b2f541dfacb5391e22e8c91ea982a6",
    "vendor": "Linux",
    "ai_description": "AI processing failed - invalid JSON response",
    "ai_severity": "",
    "ai_vendor": "",
    "ai_product": "",
    "ai_version": "",
    "ai_score": 0
}