FKIE_CVE-2026-43071

Vulnerability from fkie_nvd - Published: 2026-05-05 16:16 - Updated: 2026-05-08 13:16
Severity ?
9.1 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: dcache: Limit the minimal number of bucket to two There is an OOB read problem on dentry_hashtable when user sets 'dhash_entries=1': BUG: unable to handle page fault for address: ffff888b30b774b0 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page Oops: Oops: 0000 [#1] SMP PTI RIP: 0010:__d_lookup+0x56/0x120 Call Trace: d_lookup.cold+0x16/0x5d lookup_dcache+0x27/0xf0 lookup_one_qstr_excl+0x2a/0x180 start_dirop+0x55/0xa0 simple_start_creating+0x8d/0xa0 debugfs_start_creating+0x8c/0x180 debugfs_create_dir+0x1d/0x1c0 pinctrl_init+0x6d/0x140 do_one_initcall+0x6d/0x3d0 kernel_init_freeable+0x39f/0x460 kernel_init+0x2a/0x260 There will be only one bucket in dentry_hashtable when dhash_entries is set as one, and d_hash_shift is calculated as 32 by dcache_init(). Then, following process will access more than one buckets(which memory region is not allocated) in dentry_hashtable: d_lookup b = d_hash(hash) dentry_hashtable + ((u32)hashlen >> d_hash_shift) // The C standard defines the behavior of right shift amounts // exceeding the bit width of the operand as undefined. The // result of '(u32)hashlen >> d_hash_shift' becomes 'hashlen', // so 'b' will point to an unallocated memory region. hlist_bl_for_each_entry_rcu(b) hlist_bl_first_rcu(head) h->first // read OOB! Fix it by limiting the minimal number of dentry_hashtable bucket to two, so that 'd_hash_shift' won't exceeds the bit width of type u32.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/277cedabb0ab86baae83fa58218be13c6d3e5526
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/426ef05e82ee52c8d0e95fc0808b7383d8352d73
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/5718df131ab78897a9dd1f2e71c3ba732d4392af
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/755b40903eff563768d4d96fd4ef51ec48adde3b
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ddd57ebce245f9c7e2f6902a6c087d6186d2385d
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f08fe8891c3eeb63b73f9f1f6d97aa629c821579
Impacted products
Vendor Product Version
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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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\u0027dhash_entries=1\u0027:\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 \u003e\u003e 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 \u0027(u32)hashlen \u003e\u003e d_hash_shift\u0027 becomes \u0027hashlen\u0027,\n    // so \u0027b\u0027 will point to an unallocated memory region.\n  hlist_bl_for_each_entry_rcu(b)\n   hlist_bl_first_rcu(head)\n    h-\u003efirst  // read OOB!\n\nFix it by limiting the minimal number of dentry_hashtable bucket to two,\nso that \u0027d_hash_shift\u0027 won\u0027t exceeds the bit width of type u32."
    }
  ],
  "id": "CVE-2026-43071",
  "lastModified": "2026-05-08T13:16:37.870",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.1,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.2,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-05-05T16:16:16.420",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/277cedabb0ab86baae83fa58218be13c6d3e5526"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/426ef05e82ee52c8d0e95fc0808b7383d8352d73"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/5718df131ab78897a9dd1f2e71c3ba732d4392af"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/755b40903eff563768d4d96fd4ef51ec48adde3b"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ddd57ebce245f9c7e2f6902a6c087d6186d2385d"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/f08fe8891c3eeb63b73f9f1f6d97aa629c821579"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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