CVE-2026-53368 (GCVE-0-2026-53368)

Vulnerability from cvelistv5 – Published: 2026-07-19 09:10 – Updated: 2026-08-05 12:35
VLAI
Title
f2fs: fix fsck inconsistency caused by incorrect nat_entry flag usage
Summary
In the Linux kernel, the following vulnerability has been resolved: f2fs: fix fsck inconsistency caused by incorrect nat_entry flag usage f2fs_need_dentry_mark() reads nat_entry flags without mutual exclusion with the checkpoint path, which can result in an incorrect inode block marking state. The scenario is as follows: create & write & fsync 'file A' write checkpoint - f2fs_do_sync_file // inline inode - f2fs_write_inode // inode folio is dirty - f2fs_write_checkpoint - f2fs_flush_merged_writes - f2fs_sync_node_pages - f2fs_fsync_node_pages // no dirty node - f2fs_need_inode_block_update // return true - f2fs_fsync_node_pages // inode dirtied - f2fs_need_dentry_mark //return true - f2fs_flush_nat_entries - f2fs_write_checkpoint end - __write_node_folio // inode with DENT_BIT_SHIFT set SPO, "fsck --dry-run" find inode has already checkpointed but still with DENT_BIT_SHIFT set The state observed by f2fs_need_dentry_mark() can differ from the state observed in __write_node_folio() after acquiring sbi->node_write. The root cause is that the semantics of IS_CHECKPOINTED and HAS_FSYNCED_INODE are only guaranteed after the checkpoint write has fully completed. This patch moves set_dentry_mark() into __write_node_folio() and protects it with the sbi->node_write lock.
Severity
7.1 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 88bd02c9472a166b706284a34a84f1243322d782 , < bedb710b63ae1bd617e65d0a8cf6cea1200b3753 (git)
Affected: 88bd02c9472a166b706284a34a84f1243322d782 , < b28a83ea4934215b5de906c3ee4fbfbc651573e0 (git)
Affected: 88bd02c9472a166b706284a34a84f1243322d782 , < 019f9dda7f66e55eb94cd32e1d3fff5835f73fbc (git)
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Linux Linux Affected: 3.18
Unaffected: 0 , < 3.18 (semver)
Unaffected: 6.18.30 , ≤ 6.18.* (semver)
Unaffected: 7.0.7 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix fsck inconsistency caused by incorrect nat_entry flag usage\n\nf2fs_need_dentry_mark() reads nat_entry flags without mutual exclusion\nwith the checkpoint path, which can result in an incorrect inode block\nmarking state. The scenario is as follows:\n\ncreate \u0026 write \u0026 fsync \u0027file A\u0027                 write checkpoint\n- f2fs_do_sync_file // inline inode\n - f2fs_write_inode // inode folio is dirty\n                                                - f2fs_write_checkpoint\n                                                 - f2fs_flush_merged_writes\n                                                 - f2fs_sync_node_pages\n - f2fs_fsync_node_pages // no dirty node\n - f2fs_need_inode_block_update // return true\n - f2fs_fsync_node_pages // inode dirtied\n  - f2fs_need_dentry_mark //return true\n                                                 - f2fs_flush_nat_entries\n                                                - f2fs_write_checkpoint end\n  - __write_node_folio // inode with DENT_BIT_SHIFT set\n  SPO, \"fsck --dry-run\" find inode has already checkpointed but still\n  with DENT_BIT_SHIFT set\n\nThe state observed by f2fs_need_dentry_mark() can differ from the state\nobserved in __write_node_folio() after acquiring sbi-\u003enode_write. The\nroot cause is that the semantics of IS_CHECKPOINTED and\nHAS_FSYNCED_INODE are only guaranteed after the checkpoint write has\nfully completed.\n\nThis patch moves set_dentry_mark() into __write_node_folio() and\nprotects it with the sbi-\u003enode_write lock."
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              "value": "AV:L - The bug is reached via local filesystem syscalls (fsync/fdatasync on a writable file) on an F2FS mount. F2FS is primarily deployed on local flash storage (Android /data, ChromeOS, embedded), not as a network-facing attack surface.\nAC:L - An attacker controls both sides of the race by concurrently fsyncing an inline inode while triggering a checkpoint (e.g., via sync(2), heavy writeback, or background checkpoint/GC threads). No conditions outside attacker influence are required beyond routine concurrent I/O.\nPR:L - Exploitation requires only unprivileged write access to files on the F2FS filesystem plus the ability to issue fsync/sync syscalls. No CAP_SYS_ADMIN, mount privileges, or init-namespace root are needed.\nUI:N - No victim interaction is required; the attacker performs the write and fsync operations on files they can already modify.\nS:U - The impact is confined to F2FS on-disk metadata and recovery semantics within the same kernel/filesystem security boundary. There is no VM escape, sandbox breakout, or cross-authority boundary crossing.\nC:N - The bug causes incorrect setting of the DENT_BIT_SHIFT recovery flag on a node block. It does not read kernel memory, leak pointers, or disclose data beyond what the attacker already wrote.\nI:H - The race writes incorrect dentry recovery metadata to disk (checkpointed inode still marked with DENT_BIT_SHIFT), producing fsck-detectable filesystem inconsistency and potentially breaking roll-forward recovery of fsynced data after sudden power-off.\nA:H - Corrupted recovery metadata can cause mount-time recovery failures (as seen in the related atomic-write variant returning -EINVAL from f2fs_recover_inode_page) and fsck-detected inconsistency after power loss, degrading filesystem availability on F2FS-backed systems such as Android devices."
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    "state": "PUBLISHED"
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix fsck inconsistency caused by incorrect nat_entry flag usage\n\nf2fs_need_dentry_mark() reads nat_entry flags without mutual exclusion\nwith the checkpoint path, which can result in an incorrect inode block\nmarking state. The scenario is as follows:\n\ncreate \u0026 write \u0026 fsync \u0027file A\u0027                 write checkpoint\n- f2fs_do_sync_file // inline inode\n - f2fs_write_inode // inode folio is dirty\n                                                - f2fs_write_checkpoint\n                                                 - f2fs_flush_merged_writes\n                                                 - f2fs_sync_node_pages\n - f2fs_fsync_node_pages // no dirty node\n - f2fs_need_inode_block_update // return true\n - f2fs_fsync_node_pages // inode dirtied\n  - f2fs_need_dentry_mark //return true\n                                                 - f2fs_flush_nat_entries\n                                                - f2fs_write_checkpoint end\n  - __write_node_folio // inode with DENT_BIT_SHIFT set\n  SPO, \"fsck --dry-run\" find inode has already checkpointed but still\n  with DENT_BIT_SHIFT set\n\nThe state observed by f2fs_need_dentry_mark() can differ from the state\nobserved in __write_node_folio() after acquiring sbi-\u003enode_write. The\nroot cause is that the semantics of IS_CHECKPOINTED and\nHAS_FSYNCED_INODE are only guaranteed after the checkpoint write has\nfully completed.\n\nThis patch moves set_dentry_mark() into __write_node_folio() and\nprotects it with the sbi-\u003enode_write lock."
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        "lastModified": "2026-07-29T16:55:46.613",
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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.

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  • 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.
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  • 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.


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