btrfs: fix assertion failure when splitting ordered extent after transaction abort

{
  "id": "b0fdf1fbdd170965a0ac12c22ee6f6ecd3a15f463fae93efdf2e458ae51b9a08",
  "url": "https://osv.dev/vulnerability/CVE-2025-21754",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "btrfs: fix assertion failure when splitting ordered extent after transaction abort",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: btrfs: fix assertion failure when splitting ordered extent after transaction abort If while we are doing a direct IO write a transaction abort happens, we mark all existing ordered extents with the BTRFS_ORDERED_IOERR flag (done at btrfs_destroy_ordered_extents()), and then after that if we enter btrfs_split_ordered_extent() and the ordered extent has bytes left (meaning we have a bio that doesn't cover the whole ordered extent, see details at btrfs_extract_ordered_extent()), we will fail on the following assertion at btrfs_split_ordered_extent(): ASSERT(!(flags & ~BTRFS_ORDERED_TYPE_FLAGS)); because the BTRFS_ORDERED_IOERR flag is set and the definition of BTRFS_ORDERED_TYPE_FLAGS is just the union of all flags that identify the type of write (regular, nocow, prealloc, compressed, direct IO, encoded). Fix this by returning an error from btrfs_extract_ordered_extent() if we find the BTRFS_ORDERED_IOERR flag in the ordered extent. The error will be the error that resulted in the transaction abort or -EIO if no transaction abort happened. This was recently reported by syzbot with the following trace: FAULT_INJECTION: forcing a failure. name failslab, interval 1, probability 0, space 0, times 1 CPU: 0 UID: 0 PID: 5321 Comm: syz.0.0 Not tainted 6.13.0-rc5-syzkaller #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [in",
    "evidence": "osv:CVE-2025-21754",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.6.78",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.14",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.13.3",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2025-21754",
      "aliases": [
        "CVE-2025-21754"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
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                  "fixed": "927b930f117bbae730a853c1dc43da8afe8380fa"
                },
                {
                  "fixed": "0ff88c2a742a7cbaa4d08507d864737d099b435a"
                },
                {
                  "fixed": "8ea8db4216d1029527ab4666f730650419451e32"
                },
                {
                  "fixed": "0d85f5c2dd91df6b5da454406756f463ba923b69"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-21754.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.5.0"
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                {
                  "fixed": "6.6.78"
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            {
              "type": "ECOSYSTEM",
              "events": [
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                  "introduced": "6.7.0"
                },
                {
                  "fixed": "6.12.14"
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              ]
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            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
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                {
                  "fixed": "6.13.3"
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          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-21754.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:42.254341815Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/0d85f5c2dd91df6b5da454406756f463ba923b69",
        "https://git.kernel.org/stable/c/0ff88c2a742a7cbaa4d08507d864737d099b435a",
        "https://git.kernel.org/stable/c/8ea8db4216d1029527ab4666f730650419451e32",
        "https://git.kernel.org/stable/c/927b930f117bbae730a853c1dc43da8afe8380fa",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21754.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-21754",
        "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/2025/21xxx/CVE-2025-21754.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-21754",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 509778,
  "published_at": "2025-02-27T02:12:23.738+00:00"
}