CVE-2026-90261 (GCVE-0-2026-90261)

Vulnerability from cvelistv5 – Published: 2026-09-17 16:07 – Updated: 2026-09-17 16:07
VLAI
Title
btrfs: zoned: flush active metadata block group at btree_writepages() start
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.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 13bb483d32abb6f8ebd40141d87eb68f11cc2dd2 , < e2de2989adb3e58c2320e57c255f52e065667b5e (git)
Affected: 13bb483d32abb6f8ebd40141d87eb68f11cc2dd2 , < ecc05eda9a346848ae01a6c8bfa3f0bec133bd8b (git)
Affected: fca3a1cd3ba47f1815e0c0fcdc9aafaf02ee0a75 (git)
Affected: 6.5.5 , < 6.6 (semver)
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Linux Linux Affected: 6.6
Unaffected: 0 , < 6.6 (semver)
Unaffected: 7.2.6 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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{
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          "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."
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        "dateUpdated": "2026-09-17T16:07:58.806Z",
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    "datePublished": "2026-09-17T16:07:58.806Z",
    "dateReserved": "2026-09-11T19:38:34.796Z",
    "dateUpdated": "2026-09-17T16:07:58.806Z",
    "state": "PUBLISHED"
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          {
            "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."
          }
        ],
        "id": "CVE-2026-90261",
        "lastModified": "2026-09-17T17:17:22.537",
        "metrics": {},
        "published": "2026-09-17T17:17:22.537",
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            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    }
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}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.