CVE-2026-43071 (GCVE-0-2026-43071)

Vulnerability from cvelistv5 – Published: 2026-05-05 15:29 – Updated: 2026-05-05 15:29
VLAI?
Title
dcache: Limit the minimal number of bucket to two
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.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 426ef05e82ee52c8d0e95fc0808b7383d8352d73 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < ddd57ebce245f9c7e2f6902a6c087d6186d2385d (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 755b40903eff563768d4d96fd4ef51ec48adde3b (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 5718df131ab78897a9dd1f2e71c3ba732d4392af (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 277cedabb0ab86baae83fa58218be13c6d3e5526 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < f08fe8891c3eeb63b73f9f1f6d97aa629c821579 (git)
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    Linux Linux Unaffected: 6.6.136 , ≤ 6.6.* (semver)
Unaffected: 6.12.83 , ≤ 6.12.* (semver)
Unaffected: 6.18.24 , ≤ 6.18.* (semver)
Unaffected: 6.19.14 , ≤ 6.19.* (semver)
Unaffected: 7.0.1 , ≤ 7.0.* (semver)
Unaffected: 7.1-rc1 , ≤ * (original_commit_for_fix)
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{
  "containers": {
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/dcache.c"
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              "status": "unaffected",
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              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1-rc1",
              "versionType": "original_commit_for_fix"
            }
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      ],
      "cpeApplicability": [
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              "operator": "OR"
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      "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."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-05T15:29:28.081Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
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          "url": "https://git.kernel.org/stable/c/426ef05e82ee52c8d0e95fc0808b7383d8352d73"
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          "url": "https://git.kernel.org/stable/c/ddd57ebce245f9c7e2f6902a6c087d6186d2385d"
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          "url": "https://git.kernel.org/stable/c/f08fe8891c3eeb63b73f9f1f6d97aa629c821579"
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      ],
      "title": "dcache: Limit the minimal number of bucket to two",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-43071",
    "datePublished": "2026-05-05T15:29:28.081Z",
    "dateReserved": "2026-05-01T14:12:55.982Z",
    "dateUpdated": "2026-05-05T15:29:28.081Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-43071\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-05-05T16:16:16.420\",\"lastModified\":\"2026-05-05T16:16:16.420\",\"vulnStatus\":\"Received\",\"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.\"}],\"metrics\":{},\"references\":[{\"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\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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