9p: add missing locking around taking dentry fid list

{
  "id": "a412004e7ada94ccb2613dc8abe38553ae17e3e695fb9844c94b30d0b249b93f",
  "url": "https://osv.dev/vulnerability/CVE-2024-39463",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "9p: add missing locking around taking dentry fid list",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: 9p: add missing locking around taking dentry fid list Fix a use-after-free on dentry's d_fsdata fid list when a thread looks up a fid through dentry while another thread unlinks it: UAF thread: refcount_t: addition on 0; use-after-free. p9_fid_get linux/./include/net/9p/client.h:262 v9fs_fid_find+0x236/0x280 linux/fs/9p/fid.c:129 v9fs_fid_lookup_with_uid linux/fs/9p/fid.c:181 v9fs_fid_lookup+0xbf/0xc20 linux/fs/9p/fid.c:314 v9fs_vfs_getattr_dotl+0xf9/0x360 linux/fs/9p/vfs_inode_dotl.c:400 vfs_statx+0xdd/0x4d0 linux/fs/stat.c:248 Freed by: p9_fid_destroy (inlined) p9_client_clunk+0xb0/0xe0 linux/net/9p/client.c:1456 p9_fid_put linux/./include/net/9p/client.h:278 v9fs_dentry_release+0xb5/0x140 linux/fs/9p/vfs_dentry.c:55 v9fs_remove+0x38f/0x620 linux/fs/9p/vfs_inode.c:518 vfs_unlink+0x29a/0x810 linux/fs/namei.c:4335 The problem is that d_fsdata was not accessed under d_lock, because d_release() normally is only called once the dentry is otherwise no longer accessible but since we also call it explicitly in v9fs_remove that lock is required: move the hlist out of the dentry under lock then unref its fids once they are no longer accessible.",
    "evidence": "osv:CVE-2024-39463",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.15.168",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.1.94",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.34",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.9.5",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2024-39463",
      "aliases": [
        "CVE-2024-39463"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
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              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
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                  "introduced": "154372e67d4053e56591245eb413686621941333"
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                {
                  "fixed": "3bb6763a8319170c2d41c4232c8e7e4c37dcacfb"
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                {
                  "fixed": "cb299cdba09f46f090b843d78ba26b667d50a456"
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                {
                  "fixed": "f0c5c944c6d8614c19e6e9a97fd2011dcd30e8f5"
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                  "fixed": "fe17ebf22feb4ad7094d597526d558a49aac92b4"
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                  "fixed": "c898afdc15645efb555acb6d85b484eb40a45409"
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          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-39463.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.11.0"
                },
                {
                  "fixed": "5.15.168"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.16.0"
                },
                {
                  "fixed": "6.1.94"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
                },
                {
                  "fixed": "6.6.34"
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              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.7.0"
                },
                {
                  "fixed": "6.9.5"
                }
              ]
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          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-39463.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:25.453136201Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/3bb6763a8319170c2d41c4232c8e7e4c37dcacfb",
        "https://git.kernel.org/stable/c/c898afdc15645efb555acb6d85b484eb40a45409",
        "https://git.kernel.org/stable/c/cb299cdba09f46f090b843d78ba26b667d50a456",
        "https://git.kernel.org/stable/c/f0c5c944c6d8614c19e6e9a97fd2011dcd30e8f5",
        "https://git.kernel.org/stable/c/fe17ebf22feb4ad7094d597526d558a49aac92b4",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/39xxx/CVE-2024-39463.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2024-39463",
        "https://www.zerodayinitiative.com/advisories/ZDI-24-1194/",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/39xxx/CVE-2024-39463.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2024-39463",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 491742,
  "published_at": "2024-06-25T14:25:02.887+00:00"
}