fs: writeback: fix use-after-free in __mark_inode_dirty()

{
  "id": "f88d5b2c837cecfe47da8661f8753dbfb749422d060485f8e31ac81bea9adb33",
  "url": "https://osv.dev/vulnerability/CVE-2025-39866",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "fs: writeback: fix use-after-free in __mark_inode_dirty()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: fs: writeback: fix use-after-free in __mark_inode_dirty() An use-after-free issue occurred when __mark_inode_dirty() get the bdi_writeback that was in the progress of switching. CPU: 1 PID: 562 Comm: systemd-random- Not tainted 6.6.56-gb4403bd46a8e #1 ...... pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : __mark_inode_dirty+0x124/0x418 lr : __mark_inode_dirty+0x118/0x418 sp : ffffffc08c9dbbc0 ........ Call trace: __mark_inode_dirty+0x124/0x418 generic_update_time+0x4c/0x60 file_modified+0xcc/0xd0 ext4_buffered_write_iter+0x58/0x124 ext4_file_write_iter+0x54/0x704 vfs_write+0x1c0/0x308 ksys_write+0x74/0x10c __arm64_sys_write+0x1c/0x28 invoke_syscall+0x48/0x114 el0_svc_common.constprop.0+0xc0/0xe0 do_el0_svc+0x1c/0x28 el0_svc+0x40/0xe4 el0t_64_sync_handler+0x120/0x12c el0t_64_sync+0x194/0x198 Root cause is: systemd-random-seed kworker ---------------------------------------------------------------------- ___mark_inode_dirty inode_switch_wbs_work_fn spin_lock(&inode->i_lock); inode_attach_wb locked_inode_to_wb_and_lock_list get inode->i_wb spin_unlock(&inode->i_lock); spin_lock(&wb->list_lock) spin_lock(&inode->i_lock) inode_io_list_move_locked spin_unlock(&wb->list_lock) spin_unlock(&inode->i_lock) spin_lock(&old_wb->list_lock) inode_do_switch_wbs spin_lock(&inode->i_lock) inode->i_wb = new_wb spin_unlock(&inode->i_lock) spin_unlock(&old_wb->list_lock) wb_put_many(old_wb, nr_switched) cgwb_",
    "evidence": "osv:CVE-2025-39866",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
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            "value": "5.10.247",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.15.192",
            "evidence": "/affected/1/ranges"
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          {
            "value": "6.1.151",
            "evidence": "/affected/1/ranges"
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            "evidence": "/affected/1/ranges"
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          {
            "value": "6.12.46",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.16.6",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2025-39866",
      "aliases": [
        "CVE-2025-39866"
      ],
      "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": [
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              "type": "GIT",
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                {
                  "fixed": "b187c976111960e6e54a6b1fff724f6e3d39406c"
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                {
                  "fixed": "1edc2feb9c759a9883dfe81cb5ed231412d8b2e4"
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            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-39866.json"
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          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
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          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-39866.json"
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      "modified": "2026-10-28T02:30:39.661720958Z",
      "provider": "osv",
      "references": [
        "https://cert-portal.siemens.com/productcert/html/ssa-019113.html",
        "https://cert-portal.siemens.com/productcert/html/ssa-032379.html",
        "https://cert-portal.siemens.com/productcert/html/ssa-082556.html",
        "https://cert-portal.siemens.com/productcert/html/ssa-457936.html",
        "https://git.kernel.org/stable/c/1edc2feb9c759a9883dfe81cb5ed231412d8b2e4",
        "https://git.kernel.org/stable/c/b187c976111960e6e54a6b1fff724f6e3d39406c",
        "https://git.kernel.org/stable/c/bf89b1f87c72df79cf76203f71fbf8349cd5c9de",
        "https://git.kernel.org/stable/c/c8c14adf80bd1a6e4a1d7ee9c2a816881c26d17a",
        "https://git.kernel.org/stable/c/d02d2c98d25793902f65803ab853b592c7a96b29",
        "https://git.kernel.org/stable/c/e2a14bbae5d8bacaa301362744a110e2be40a3a3",
        "https://git.kernel.org/stable/c/e63052921f1b25a836feb1500b841bff7a4a0456",
        "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/39xxx/CVE-2025-39866.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-39866",
        "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/2025/39xxx/CVE-2025-39866.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-39866",
        "evidence": "/id"
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    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 507276,
  "published_at": "2025-09-19T15:26:35.725+00:00"
}