CVE-2026-64158 (GCVE-0-2026-64158)

Vulnerability from cvelistv5 – Published: 2026-07-19 15:40 – Updated: 2026-07-19 15:40
VLAI
Title
netfs: Fix write streaming disablement if fd open O_RDWR
Summary
In the Linux kernel, the following vulnerability has been resolved: netfs: Fix write streaming disablement if fd open O_RDWR In netfs_perform_write(), "write streaming" (the caching of dirty data in dirty but !uptodate folios) is performed to avoid the need to read data that is just going to get immediately overwritten. However, this is/will be disabled in three circumstances: if the fd is open O_RDWR, if fscache is in use (as we need to round out the blocks for DIO) or if content encryption is enabled (again for rounding out purposes). The idea behind disabling it if the fd is open O_RDWR is that we'd need to flush the write-streaming page before we could read the data, particularly through mmap. But netfs now fills in the gaps if ->read_folio() is called on the page, so that is unnecessary. Further, this doesn't actually work if a separate fd is open for reading. Fix this by removing the check for O_RDWR, thereby allowing streaming writes even when we might read. This caused a number of problems with the generic/522 xfstest, but those are now fixed.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: c38f4e96e605f17990e871214e6ea1496bc4e65f , < 9adf8e47d73d5e3c2fe77dea649dcde350ccd65c (git)
Affected: c38f4e96e605f17990e871214e6ea1496bc4e65f , < 616578e40dcba3f94810d841c5a52b7e3bc8ede7 (git)
Affected: c38f4e96e605f17990e871214e6ea1496bc4e65f , < 7a9fa5b020a3a40f8291a71cd44c08d931da430d (git)
Affected: c38f4e96e605f17990e871214e6ea1496bc4e65f , < 70a7b9193bbbfceaab5974de66834c64ccc875dd (git)
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Linux Linux Affected: 6.8
Unaffected: 0 , < 6.8 (semver)
Unaffected: 6.12.92 , ≤ 6.12.* (semver)
Unaffected: 6.18.34 , ≤ 6.18.* (semver)
Unaffected: 7.0.11 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
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{
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          "product": "Linux",
          "programFiles": [
            "fs/netfs/buffered_write.c"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfs: Fix write streaming disablement if fd open O_RDWR\n\nIn netfs_perform_write(), \"write streaming\" (the caching of dirty data in\ndirty but !uptodate folios) is performed to avoid the need to read data\nthat is just going to get immediately overwritten.  However, this is/will\nbe disabled in three circumstances: if the fd is open O_RDWR, if fscache is\nin use (as we need to round out the blocks for DIO) or if content\nencryption is enabled (again for rounding out purposes).\n\nThe idea behind disabling it if the fd is open O_RDWR is that we\u0027d need to\nflush the write-streaming page before we could read the data, particularly\nthrough mmap.  But netfs now fills in the gaps if -\u003eread_folio() is called\non the page, so that is unnecessary.  Further, this doesn\u0027t actually work\nif a separate fd is open for reading.\n\nFix this by removing the check for O_RDWR, thereby allowing streaming\nwrites even when we might read.\n\nThis caused a number of problems with the generic/522 xfstest, but those\nare now fixed."
        }
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      "providerMetadata": {
        "dateUpdated": "2026-07-19T15:40:45.692Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64158",
    "datePublished": "2026-07-19T15:40:45.692Z",
    "dateReserved": "2026-07-19T07:54:57.038Z",
    "dateUpdated": "2026-07-19T15:40:45.692Z",
    "state": "PUBLISHED"
  },
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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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  • 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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