CVE-2025-68774 (GCVE-0-2025-68774)

Vulnerability from cvelistv5 – Published: 2026-01-13 15:28 – Updated: 2026-01-13 15:28
VLAI?
Title
hfsplus: fix missing hfs_bnode_get() in __hfs_bnode_create
Summary
In the Linux kernel, the following vulnerability has been resolved: hfsplus: fix missing hfs_bnode_get() in __hfs_bnode_create When sync() and link() are called concurrently, both threads may enter hfs_bnode_find() without finding the node in the hash table and proceed to create it. Thread A: hfsplus_write_inode() -> hfsplus_write_system_inode() -> hfs_btree_write() -> hfs_bnode_find(tree, 0) -> __hfs_bnode_create(tree, 0) Thread B: hfsplus_create_cat() -> hfs_brec_insert() -> hfs_bnode_split() -> hfs_bmap_alloc() -> hfs_bnode_find(tree, 0) -> __hfs_bnode_create(tree, 0) In this case, thread A creates the bnode, sets refcnt=1, and hashes it. Thread B also tries to create the same bnode, notices it has already been inserted, drops its own instance, and uses the hashed one without getting the node. ``` node2 = hfs_bnode_findhash(tree, cnid); if (!node2) { <- Thread A hash = hfs_bnode_hash(cnid); node->next_hash = tree->node_hash[hash]; tree->node_hash[hash] = node; tree->node_hash_cnt++; } else { <- Thread B spin_unlock(&tree->hash_lock); kfree(node); wait_event(node2->lock_wq, !test_bit(HFS_BNODE_NEW, &node2->flags)); return node2; } ``` However, hfs_bnode_find() requires each call to take a reference. Here both threads end up setting refcnt=1. When they later put the node, this triggers: BUG_ON(!atomic_read(&node->refcnt)) In this scenario, Thread B in fact finds the node in the hash table rather than creating a new one, and thus must take a reference. Fix this by calling hfs_bnode_get() when reusing a bnode newly created by another thread to ensure the refcount is updated correctly. A similar bug was fixed in HFS long ago in commit a9dc087fd3c4 ("fix missing hfs_bnode_get() in __hfs_bnode_create") but the same issue remained in HFS+ until now.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < b68dc4134b18a3922cd33439ec614aad4172bc86 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < b9d1c6bb5f19460074ce9862cb80be86b5fb0a50 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 457f795e7abd7770de10216d7f9994a3f12a56d6 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 5882e7c8cdbb5e254a69628b780acff89c78071e (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 152af114287851583cf7e0abc10129941f19466a (git)
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    Linux Linux Unaffected: 6.1.160 , ≤ 6.1.* (semver)
Unaffected: 6.6.120 , ≤ 6.6.* (semver)
Unaffected: 6.12.64 , ≤ 6.12.* (semver)
Unaffected: 6.18.3 , ≤ 6.18.* (semver)
Unaffected: 6.19-rc1 , ≤ * (original_commit_for_fix)
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{
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/hfsplus/bnode.c"
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          "programFiles": [
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          ],
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          "vendor": "Linux",
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              "status": "unaffected",
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              "status": "unaffected",
              "version": "6.6.120",
              "versionType": "semver"
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              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
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              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.19-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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          "nodes": [
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              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.160",
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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\nhfsplus: fix missing hfs_bnode_get() in __hfs_bnode_create\n\nWhen sync() and link() are called concurrently, both threads may\nenter hfs_bnode_find() without finding the node in the hash table\nand proceed to create it.\n\nThread A:\n  hfsplus_write_inode()\n    -\u003e hfsplus_write_system_inode()\n      -\u003e hfs_btree_write()\n        -\u003e hfs_bnode_find(tree, 0)\n          -\u003e __hfs_bnode_create(tree, 0)\n\nThread B:\n  hfsplus_create_cat()\n    -\u003e hfs_brec_insert()\n      -\u003e hfs_bnode_split()\n        -\u003e hfs_bmap_alloc()\n          -\u003e hfs_bnode_find(tree, 0)\n            -\u003e __hfs_bnode_create(tree, 0)\n\nIn this case, thread A creates the bnode, sets refcnt=1, and hashes it.\nThread B also tries to create the same bnode, notices it has already\nbeen inserted, drops its own instance, and uses the hashed one without\ngetting the node.\n\n```\n\n\tnode2 = hfs_bnode_findhash(tree, cnid);\n\tif (!node2) {                                 \u003c- Thread A\n\t\thash = hfs_bnode_hash(cnid);\n\t\tnode-\u003enext_hash = tree-\u003enode_hash[hash];\n\t\ttree-\u003enode_hash[hash] = node;\n\t\ttree-\u003enode_hash_cnt++;\n\t} else {                                      \u003c- Thread B\n\t\tspin_unlock(\u0026tree-\u003ehash_lock);\n\t\tkfree(node);\n\t\twait_event(node2-\u003elock_wq,\n\t\t\t!test_bit(HFS_BNODE_NEW, \u0026node2-\u003eflags));\n\t\treturn node2;\n\t}\n```\n\nHowever, hfs_bnode_find() requires each call to take a reference.\nHere both threads end up setting refcnt=1. When they later put the node,\nthis triggers:\n\nBUG_ON(!atomic_read(\u0026node-\u003erefcnt))\n\nIn this scenario, Thread B in fact finds the node in the hash table\nrather than creating a new one, and thus must take a reference.\n\nFix this by calling hfs_bnode_get() when reusing a bnode newly created by\nanother thread to ensure the refcount is updated correctly.\n\nA similar bug was fixed in HFS long ago in commit\na9dc087fd3c4 (\"fix missing hfs_bnode_get() in __hfs_bnode_create\")\nbut the same issue remained in HFS+ until now."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-01-13T15:28:51.379Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/b68dc4134b18a3922cd33439ec614aad4172bc86"
        },
        {
          "url": "https://git.kernel.org/stable/c/b9d1c6bb5f19460074ce9862cb80be86b5fb0a50"
        },
        {
          "url": "https://git.kernel.org/stable/c/457f795e7abd7770de10216d7f9994a3f12a56d6"
        },
        {
          "url": "https://git.kernel.org/stable/c/5882e7c8cdbb5e254a69628b780acff89c78071e"
        },
        {
          "url": "https://git.kernel.org/stable/c/152af114287851583cf7e0abc10129941f19466a"
        }
      ],
      "title": "hfsplus: fix missing hfs_bnode_get() in __hfs_bnode_create",
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        "engine": "bippy-1.2.0"
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    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-68774",
    "datePublished": "2026-01-13T15:28:51.379Z",
    "dateReserved": "2025-12-24T10:30:51.035Z",
    "dateUpdated": "2026-01-13T15:28:51.379Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-68774\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-01-13T16:15:56.960\",\"lastModified\":\"2026-01-13T16:15:56.960\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nhfsplus: fix missing hfs_bnode_get() in __hfs_bnode_create\\n\\nWhen sync() and link() are called concurrently, both threads may\\nenter hfs_bnode_find() without finding the node in the hash table\\nand proceed to create it.\\n\\nThread A:\\n  hfsplus_write_inode()\\n    -\u003e hfsplus_write_system_inode()\\n      -\u003e hfs_btree_write()\\n        -\u003e hfs_bnode_find(tree, 0)\\n          -\u003e __hfs_bnode_create(tree, 0)\\n\\nThread B:\\n  hfsplus_create_cat()\\n    -\u003e hfs_brec_insert()\\n      -\u003e hfs_bnode_split()\\n        -\u003e hfs_bmap_alloc()\\n          -\u003e hfs_bnode_find(tree, 0)\\n            -\u003e __hfs_bnode_create(tree, 0)\\n\\nIn this case, thread A creates the bnode, sets refcnt=1, and hashes it.\\nThread B also tries to create the same bnode, notices it has already\\nbeen inserted, drops its own instance, and uses the hashed one without\\ngetting the node.\\n\\n```\\n\\n\\tnode2 = hfs_bnode_findhash(tree, cnid);\\n\\tif (!node2) {                                 \u003c- Thread A\\n\\t\\thash = hfs_bnode_hash(cnid);\\n\\t\\tnode-\u003enext_hash = tree-\u003enode_hash[hash];\\n\\t\\ttree-\u003enode_hash[hash] = node;\\n\\t\\ttree-\u003enode_hash_cnt++;\\n\\t} else {                                      \u003c- Thread B\\n\\t\\tspin_unlock(\u0026tree-\u003ehash_lock);\\n\\t\\tkfree(node);\\n\\t\\twait_event(node2-\u003elock_wq,\\n\\t\\t\\t!test_bit(HFS_BNODE_NEW, \u0026node2-\u003eflags));\\n\\t\\treturn node2;\\n\\t}\\n```\\n\\nHowever, hfs_bnode_find() requires each call to take a reference.\\nHere both threads end up setting refcnt=1. When they later put the node,\\nthis triggers:\\n\\nBUG_ON(!atomic_read(\u0026node-\u003erefcnt))\\n\\nIn this scenario, Thread B in fact finds the node in the hash table\\nrather than creating a new one, and thus must take a reference.\\n\\nFix this by calling hfs_bnode_get() when reusing a bnode newly created by\\nanother thread to ensure the refcount is updated correctly.\\n\\nA similar bug was fixed in HFS long ago in commit\\na9dc087fd3c4 (\\\"fix missing hfs_bnode_get() in __hfs_bnode_create\\\")\\nbut the same issue remained in HFS+ until now.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/152af114287851583cf7e0abc10129941f19466a\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/457f795e7abd7770de10216d7f9994a3f12a56d6\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/5882e7c8cdbb5e254a69628b780acff89c78071e\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b68dc4134b18a3922cd33439ec614aad4172bc86\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b9d1c6bb5f19460074ce9862cb80be86b5fb0a50\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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