btrfs: subpage: keep TOWRITE tag until folio is cleaned

{
  "id": "6e81722e9a539eec417a848cfedcfed23263deebddec37131b9e83a55fdc8066",
  "url": "https://osv.dev/vulnerability/CVE-2025-39779",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "btrfs: subpage: keep TOWRITE tag until folio is cleaned",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: btrfs: subpage: keep TOWRITE tag until folio is cleaned btrfs_subpage_set_writeback() calls folio_start_writeback() the first time a folio is written back, and it also clears the PAGECACHE_TAG_TOWRITE tag even if there are still dirty blocks in the folio. This can break ordering guarantees, such as those required by btrfs_wait_ordered_extents(). That ordering breakage leads to a real failure. For example, running generic/464 on a zoned setup will hit the following ASSERT. This happens because the broken ordering fails to flush existing dirty pages before the file size is truncated. assertion failed: !list_empty(&ordered->list) :: 0, in fs/btrfs/zoned.c:1899 ------------[ cut here ]------------ kernel BUG at fs/btrfs/zoned.c:1899! Oops: invalid opcode: 0000 [#1] SMP NOPTI CPU: 2 UID: 0 PID: 1906169 Comm: kworker/u130:2 Kdump: loaded Not tainted 6.16.0-rc6-BTRFS-ZNS+ #554 PREEMPT(voluntary) Hardware name: Supermicro Super Server/H12SSL-NT, BIOS 2.0 02/22/2021 Workqueue: btrfs-endio-write btrfs_work_helper [btrfs] RIP: 0010:btrfs_finish_ordered_zoned.cold+0x50/0x52 [btrfs] RSP: 0018:ffffc9002efdbd60 EFLAGS: 00010246 RAX: 000000000000004c RBX: ffff88811923c4e0 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff827e38b1 RDI: 00000000ffffffff RBP: ffff88810005d000 R08: 00000000ffffdfff R09: ffffffff831051c8 R10: ffffffff83055220 R11: 0000000000000000 R12: ffff8881c2458c00 R13: ffff88811923c540 R14: ffff888119",
    "evidence": "osv:CVE-2025-39779",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.12.44",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.16.4",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2025-39779",
      "aliases": [
        "CVE-2025-39779"
      ],
      "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": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "3470da3b7d87fde4b9729d4e29c2dc074cd59c10"
                },
                {
                  "fixed": "3d61136945a7008fc90d013c3c67007ce0c96131"
                },
                {
                  "fixed": "bce7a5c77a1e7a759e227b7713dde18c52da4759"
                },
                {
                  "fixed": "b1511360c8ac882b0c52caa263620538e8d73220"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-39779.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.13.0"
                },
                {
                  "fixed": "6.12.44"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.16.4"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-39779.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:25.844568973Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/3d61136945a7008fc90d013c3c67007ce0c96131",
        "https://git.kernel.org/stable/c/b1511360c8ac882b0c52caa263620538e8d73220",
        "https://git.kernel.org/stable/c/bce7a5c77a1e7a759e227b7713dde18c52da4759",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/39xxx/CVE-2025-39779.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-39779",
        "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-2025-39779.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-39779",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 492550,
  "published_at": "2025-09-11T16:56:30.395+00:00"
}