CVE-2026-99111 (GCVE-0-2026-99111)

Vulnerability from cvelistv5 – Published: 2026-10-28 10:34 – Updated: 2026-10-28 10:34
VLAI
Title
smb: client: fix data corruption with concurrent writes and O_TRUNC
Summary
In the Linux kernel, the following vulnerability has been resolved: smb: client: fix data corruption with concurrent writes and O_TRUNC cifs_do_truncate() flushes dirty pages with filemap_write_and_wait() and truncates the file on the server, but in the old code both operations ran without holding i_rwsem or invalidate_lock. A concurrent buffered write via netfs_perform_write() -- which only needs i_rwsem shared -- could dirty new pages after the flush but before the local truncation, and those pages would be silently discarded by cifs_setsize() -> truncate_pagecache(). Fix by acquiring inode_lock (exclusive i_rwsem) and filemap_invalidate_lock at the top of cifs_do_truncate(), so the entire flush-truncate-resize sequence is atomic with respect to: - buffered writes (blocked by exclusive i_rwsem, since netfs_start_io_write takes i_rwsem shared), - read page faults (blocked by exclusive invalidate_lock, since filemap_fault takes it shared), - writeback collection (blocked by netfs_wb_begin/netfs_wb_end around the server truncate and local resize, since netfs_writepages also acquires the wb lock).
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7033 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 110fee6b9bb58a5c50047fc2594d415f741b591e , < 4d143608a0445443a85c9b29f4c9f8e63d5dbfc9 (git)
Affected: 110fee6b9bb58a5c50047fc2594d415f741b591e , < ffa66fdc7d35b890606767c4d2c7ac26b4d90a99 (git)
Affected: 110fee6b9bb58a5c50047fc2594d415f741b591e , < a8603b52b39f520ea8a34def74c23fba87396d3e (git)
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Linux Linux Affected: 6.18
Unaffected: 0 , < 6.18 (semver)
Unaffected: 6.18.59 , ≤ 6.18.* (semver)
Unaffected: 7.2.13 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
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{
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          "product": "Linux",
          "programFiles": [
            "fs/smb/client/file.c"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix data corruption with concurrent writes and O_TRUNC\n\ncifs_do_truncate() flushes dirty pages with filemap_write_and_wait()\nand truncates the file on the server, but in the old code both\noperations ran without holding i_rwsem or invalidate_lock.  A\nconcurrent buffered write via netfs_perform_write() -- which only\nneeds i_rwsem shared -- could dirty new pages after the flush but\nbefore the local truncation, and those pages would be silently\ndiscarded by cifs_setsize() -\u003e truncate_pagecache().\n\nFix by acquiring inode_lock (exclusive i_rwsem) and\nfilemap_invalidate_lock at the top of cifs_do_truncate(), so the\nentire flush-truncate-resize sequence is atomic with respect to:\n\n  - buffered writes (blocked by exclusive i_rwsem, since\n    netfs_start_io_write takes i_rwsem shared),\n  - read page faults (blocked by exclusive invalidate_lock, since\n    filemap_fault takes it shared),\n  - writeback collection (blocked by netfs_wb_begin/netfs_wb_end\n    around the server truncate and local resize, since\n    netfs_writepages also acquires the wb lock)."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-28T10:34:29.053Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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      "references": [
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          "url": "https://git.kernel.org/stable/c/4d143608a0445443a85c9b29f4c9f8e63d5dbfc9"
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        },
        {
          "url": "https://git.kernel.org/stable/c/a8603b52b39f520ea8a34def74c23fba87396d3e"
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      ],
      "title": "smb: client: fix data corruption with concurrent writes and O_TRUNC",
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-99111",
    "datePublished": "2026-10-28T10:34:29.053Z",
    "dateReserved": "2026-09-25T10:25:14.392Z",
    "dateUpdated": "2026-10-28T10:34:29.053Z",
    "state": "PUBLISHED"
  },
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      "date": "2026-10-29",
      "epss": "0.00167",
      "percentile": "0.05896"
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                "programFiles": [
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        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix data corruption with concurrent writes and O_TRUNC\n\ncifs_do_truncate() flushes dirty pages with filemap_write_and_wait()\nand truncates the file on the server, but in the old code both\noperations ran without holding i_rwsem or invalidate_lock.  A\nconcurrent buffered write via netfs_perform_write() -- which only\nneeds i_rwsem shared -- could dirty new pages after the flush but\nbefore the local truncation, and those pages would be silently\ndiscarded by cifs_setsize() -\u003e truncate_pagecache().\n\nFix by acquiring inode_lock (exclusive i_rwsem) and\nfilemap_invalidate_lock at the top of cifs_do_truncate(), so the\nentire flush-truncate-resize sequence is atomic with respect to:\n\n  - buffered writes (blocked by exclusive i_rwsem, since\n    netfs_start_io_write takes i_rwsem shared),\n  - read page faults (blocked by exclusive invalidate_lock, since\n    filemap_fault takes it shared),\n  - writeback collection (blocked by netfs_wb_begin/netfs_wb_end\n    around the server truncate and local resize, since\n    netfs_writepages also acquires the wb lock)."
          }
        ],
        "id": "CVE-2026-99111",
        "lastModified": "2026-10-28T11:17:30.520",
        "metrics": {},
        "published": "2026-10-28T11:17:30.520",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/4d143608a0445443a85c9b29f4c9f8e63d5dbfc9"
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            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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          }
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Low",
      "current_release_date": "2026-10-29T09:02:53+00:00",
      "cve": "CVE-2026-99111",
      "id": "CVE-2026-99111",
      "initial_release_date": "2026-10-28T00:00:00+00:00",
      "product_status:known_affected": "185",
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      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: smb: client: fix data corruption with concurrent writes and O_TRUNC",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-99111.json",
      "version": "3"
    }
  }
}



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