CVE-2026-90261 (GCVE-0-2026-90261)
Vulnerability from cvelistv5
Published
2026-09-17 16:07
Modified
2026-10-19 09:00
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: btrfs: zoned: flush active metadata block group at btree_writepages() start btree_writepages() writes the btree inode's dirty metadata in ascending logical address order. On a zoned filesystem only one metadata and one system block group is active for writing at a time, and check_bg_is_active() (via btrfs_check_meta_write_pointer()) pivots the active block group as writeback moves from one block group to the next. If the active block group sits at a higher logical address than another block group that also holds dirty metadata, the ascending walk reaches the lower one first and, to write it, has to finish the active block group and activate the lower one. It cannot finish a block group that still has unsent IO, and during WB_SYNC_ALL && !for_sync (commit) writeback it deliberately refuses to wait for that IO under fs_info->zoned_meta_io_lock, as that can deadlock. The pivot thus cannot issue the submission itself either, so it gives up: btrfs_check_meta_write_pointer() returns -EAGAIN, which btrfs_write_and_wait_transaction() treats as fatal and aborts the transaction, forcing the filesystem read-only. This happens intermittently under metadata-heavy relocation (e.g. fstests btrfs/187). Flush the active metadata and system block groups at the start of btree_writepages(), under the fs_info->zoned_meta_io_lock it already holds, so they have no unsent IO left and the later pivot can finish them and make forward progress.
References
Impacted products
Vendor Product Version
Linux Linux Version: 13bb483d32abb6f8ebd40141d87eb68f11cc2dd2
Version: 13bb483d32abb6f8ebd40141d87eb68f11cc2dd2
Version: 13bb483d32abb6f8ebd40141d87eb68f11cc2dd2
Version: fca3a1cd3ba47f1815e0c0fcdc9aafaf02ee0a75
Version: 6.5.5   ≤
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/btrfs/extent_io.c"
          ],
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          "vendor": "Linux",
          "versions": [
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              "versionType": "git"
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          "product": "Linux",
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          "vendor": "Linux",
          "versions": [
            {
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              "version": "6.6"
            },
            {
              "lessThan": "6.6",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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            {
              "lessThanOrEqual": "6.18.*",
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              "version": "6.18.57",
              "versionType": "semver"
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            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
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            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.57",
                  "versionStartIncluding": "6.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.6",
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                },
                {
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                  "versionStartIncluding": "6.5.5",
                  "vulnerable": true
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              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: zoned: flush active metadata block group at btree_writepages() start\n\nbtree_writepages() writes the btree inode\u0027s dirty metadata in ascending\nlogical address order. On a zoned filesystem only one metadata and one\nsystem block group is active for writing at a time, and\ncheck_bg_is_active() (via btrfs_check_meta_write_pointer()) pivots the\nactive block group as writeback moves from one block group to the next.\n\nIf the active block group sits at a higher logical address than another\nblock group that also holds dirty metadata, the ascending walk reaches\nthe lower one first and, to write it, has to finish the active block\ngroup and activate the lower one. It cannot finish a block group that\nstill has unsent IO, and during WB_SYNC_ALL \u0026\u0026 !for_sync (commit)\nwriteback it deliberately refuses to wait for that IO under\nfs_info-\u003ezoned_meta_io_lock, as that can deadlock. The pivot thus cannot\nissue the submission itself either, so it gives up:\nbtrfs_check_meta_write_pointer() returns -EAGAIN, which\nbtrfs_write_and_wait_transaction() treats as fatal and aborts the\ntransaction, forcing the filesystem read-only. This happens\nintermittently under metadata-heavy relocation (e.g. fstests btrfs/187).\n\nFlush the active metadata and system block groups at the start of\nbtree_writepages(), under the fs_info-\u003ezoned_meta_io_lock it already\nholds, so they have no unsent IO left and the later pivot can finish\nthem and make forward progress."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:00:37.715Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/58b0ab0340ce04a057169d42cbacbf786063813d"
        },
        {
          "url": "https://git.kernel.org/stable/c/e2de2989adb3e58c2320e57c255f52e065667b5e"
        },
        {
          "url": "https://git.kernel.org/stable/c/ecc05eda9a346848ae01a6c8bfa3f0bec133bd8b"
        }
      ],
      "title": "btrfs: zoned: flush active metadata block group at btree_writepages() start",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90261",
    "datePublished": "2026-09-17T16:07:58.806Z",
    "dateReserved": "2026-09-11T19:38:34.796Z",
    "dateUpdated": "2026-10-19T09:00:37.715Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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