CVE-2026-64159 (GCVE-0-2026-64159)

Vulnerability from cvelistv5 – Published: 2026-07-19 15:40 – Updated: 2026-07-19 15:40
VLAI
Title
netfs: Fix zeropoint update where i_size > remote_i_size
Summary
In the Linux kernel, the following vulnerability has been resolved: netfs: Fix zeropoint update where i_size > remote_i_size Fix the update of the zero point[*] by netfs_release_folio() when there is uncommitted data in the pagecache beyond the folio being released but the on-server EOF is in this folio (ie. i_size > remote_i_size). The update needs to limit zero_point to remote_i_size, not i_size as i_size is a local phenomenon reflecting updates made locally to the pagecache, not stuff written to the server. remote_i_size tracks the server's i_size. [*] The zero point is the file position from which we can assume that the server will just return zeros, so we can avoid generating reads. Note that netfs_invalidate_folio() probably doesn't need fixing as zero_point should be updated by setattr after truncation or fallocate. Found with: fsx -q -N 1000000 -p 10000 -o 128000 -l 600000 \ /xfstest.test/junk --replay-ops=junk.fsxops using the following as junk.fsxops: truncate 0x0 0x1bbae 0x82864 write 0x3ef2e 0xf9c8 0x1bbae write 0x67e05 0xcb5a 0x4e8f6 mapread 0x57781 0x85b6 0x7495f copy_range 0x5d3d 0x10329 0x54fac 0x7495f write 0x64710 0x1c2b 0x7495f mapread 0x64000 0x1000 0x7495f on cifs with the default cache option. It shows read-gaps on folio 0x64 failing with a short read (ie. it hits EOF) if the FMODE_READ check is commented out in netfs_perform_write(): if (//(file->f_mode & FMODE_READ) || netfs_is_cache_enabled(ctx)) { and no fscache. This was initially found with the generic/522 xfstest.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: cce6bfa6ca0e30af9927b0074c97fe6a92f28092 , < 5cd5207de519ef0c085f4f559adf5eefcb4c5202 (git)
Affected: cce6bfa6ca0e30af9927b0074c97fe6a92f28092 , < 4543a4d737944134a1394afe797622546fbcc98a (git)
Affected: e2814004138a541110d4b2dc254a8f619c2c4ce0 (git)
Affected: 6.10.8 , < 6.11 (semver)
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Linux Linux Affected: 6.11
Unaffected: 0 , < 6.11 (semver)
Unaffected: 7.0.11 , ≤ 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\nnetfs: Fix zeropoint update where i_size \u003e remote_i_size\n\nFix the update of the zero point[*] by netfs_release_folio() when there is\nuncommitted data in the pagecache beyond the folio being released but the\non-server EOF is in this folio (ie. i_size \u003e remote_i_size).  The update\nneeds to limit zero_point to remote_i_size, not i_size as i_size is a local\nphenomenon reflecting updates made locally to the pagecache, not stuff\nwritten to the server.  remote_i_size tracks the server\u0027s i_size.\n\n[*] The zero point is the file position from which we can assume that the\n    server will just return zeros, so we can avoid generating reads.\n\nNote that netfs_invalidate_folio() probably doesn\u0027t need fixing as\nzero_point should be updated by setattr after truncation or fallocate.\n\nFound with:\n\n    fsx -q -N 1000000 -p 10000 -o 128000 -l 600000 \\\n        /xfstest.test/junk --replay-ops=junk.fsxops\n\nusing the following as junk.fsxops:\n\n    truncate 0x0 0x1bbae 0x82864\n    write 0x3ef2e 0xf9c8 0x1bbae\n    write 0x67e05 0xcb5a 0x4e8f6\n    mapread 0x57781 0x85b6 0x7495f\n    copy_range 0x5d3d 0x10329 0x54fac 0x7495f\n    write 0x64710 0x1c2b 0x7495f\n    mapread 0x64000 0x1000 0x7495f\n\non cifs with the default cache option.\n\nIt shows read-gaps on folio 0x64 failing with a short read (ie. it hits\nEOF) if the FMODE_READ check is commented out in netfs_perform_write():\n\n                if (//(file-\u003ef_mode \u0026 FMODE_READ) ||\n                    netfs_is_cache_enabled(ctx)) {\n\nand no fscache.  This was initially found with the generic/522 xfstest."
        }
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        {
          "url": "https://git.kernel.org/stable/c/4543a4d737944134a1394afe797622546fbcc98a"
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      "title": "netfs: Fix zeropoint update where i_size \u003e remote_i_size",
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    "datePublished": "2026-07-19T15:40:46.400Z",
    "dateReserved": "2026-07-19T07:54:57.038Z",
    "dateUpdated": "2026-07-19T15:40:46.400Z",
    "state": "PUBLISHED"
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-07-20T10:59:39+00:00",
      "cve": "CVE-2026-64159",
      "id": "CVE-2026-64159",
      "initial_release_date": "2026-07-19T00:00:00+00:00",
      "product_status:known_affected": "76",
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      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: netfs: Fix zeropoint update where i_size \u003e remote_i_size",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64159.json",
      "version": "3"
    }
  }
}



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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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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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