f2fs: fix to trigger foreground gc during f2fs_map_blocks() in lfs mode

{
  "id": "e16cc008d018bc8c1745282aa8037e30cbb216410e2e0206b8681c2442da2726",
  "url": "https://osv.dev/vulnerability/CVE-2025-38626",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "f2fs: fix to trigger foreground gc during f2fs_map_blocks() in lfs mode",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: f2fs: fix to trigger foreground gc during f2fs_map_blocks() in lfs mode w/ \"mode=lfs\" mount option, generic/299 will cause system panic as below: ------------[ cut here ]------------ kernel BUG at fs/f2fs/segment.c:2835! Call Trace: f2fs_allocate_data_block+0x6f4/0xc50 f2fs_map_blocks+0x970/0x1550 f2fs_iomap_begin+0xb2/0x1e0 iomap_iter+0x1d6/0x430 __iomap_dio_rw+0x208/0x9a0 f2fs_file_write_iter+0x6b3/0xfa0 aio_write+0x15d/0x2e0 io_submit_one+0x55e/0xab0 __x64_sys_io_submit+0xa5/0x230 do_syscall_64+0x84/0x2f0 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0010:new_curseg+0x70f/0x720 The root cause of we run out-of-space is: in f2fs_map_blocks(), f2fs may trigger foreground gc only if it allocates any physical block, it will be a little bit later when there is multiple threads writing data w/ aio/dio/bufio method in parallel, since we always use OPU in lfs mode, so f2fs_map_blocks() does block allocations aggressively. In order to fix this issue, let's give a chance to trigger foreground gc in prior to block allocation in f2fs_map_blocks().",
    "evidence": "osv:CVE-2025-38626",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
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            "value": "5.15.209",
            "evidence": "/affected/1/ranges"
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            "value": "6.1.167",
            "evidence": "/affected/1/ranges"
          },
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            "value": "6.6.102",
            "evidence": "/affected/1/ranges"
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          {
            "value": "6.12.42",
            "evidence": "/affected/1/ranges"
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          {
            "value": "6.15.10",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.16.1",
            "evidence": "/affected/1/ranges"
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        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2025-38626",
      "aliases": [
        "CVE-2025-38626"
      ],
      "affected": [
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          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-38626.json"
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            "ecosystem": "Linux"
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          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-38626.json"
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      ],
      "modified": "2026-10-28T02:30:24.346846416Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/1005a3ca28e90c7a64fa43023f866b960a60f791",
        "https://git.kernel.org/stable/c/264ede8a52f18647ed5bb5f2bd9bf54f556ad8f5",
        "https://git.kernel.org/stable/c/385e64a0744584397b4b52b27c96703516f39968",
        "https://git.kernel.org/stable/c/82765ce5c7a56f9309ee45328e763610eaf11253",
        "https://git.kernel.org/stable/c/c737047f4665232d1e26b3620bc62df334545451",
        "https://git.kernel.org/stable/c/d2f280f43a2a9d918fd23169ff3a6f3b65c7cec5",
        "https://git.kernel.org/stable/c/f289690f50a01c3e085d87853392d5b7436a4cee",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/38xxx/CVE-2025-38626.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-38626",
        "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/2025/38xxx/CVE-2025-38626.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-38626",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 490808,
  "published_at": "2025-08-22T16:00:34.867+00:00"
}