Unity Linux 20.1050e Security Update: kernel (UTSA-2026-099951)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(336445);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/08/17");

  script_cve_id("CVE-2026-45985");

  script_name(english:"Unity Linux 20.1050e Security Update: kernel (UTSA-2026-099951)");

  script_set_attribute(attribute:"synopsis", value:
"The Unity Linux host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The Unity Linux 20 host has a package installed that is affected by a vulnerability as referenced in the
UTSA-2026-099951 advisory.

    In the Linux kernel, the following vulnerability has been resolved:

    ext4: don't set EXT4_GET_BLOCKS_CONVERT when splitting before submitting I/O

    When allocating blocks during within-EOF DIO and writeback with
    dioread_nolock enabled, EXT4_GET_BLOCKS_PRE_IO was set to split an
    existing large unwritten extent. However, EXT4_GET_BLOCKS_CONVERT was
    set when calling ext4_split_convert_extents(), which may potentially
    result in stale data issues.

    Assume we have an unwritten extent, and then DIO writes the second half.

       [UUUUUUUUUUUUUUUU] on-disk extent        U: unwritten extent
       [UUUUUUUUUUUUUUUU] extent status tree
                |<-   ->| ----> dio write this range

    First, ext4_iomap_alloc() call ext4_map_blocks() with
    EXT4_GET_BLOCKS_PRE_IO, EXT4_GET_BLOCKS_UNWRIT_EXT and
    EXT4_GET_BLOCKS_CREATE flags set. ext4_map_blocks() find this extent and
    call ext4_split_convert_extents() with EXT4_GET_BLOCKS_CONVERT and the
    above flags set.

    Then, ext4_split_convert_extents() calls ext4_split_extent() with
    EXT4_EXT_MAY_ZEROOUT, EXT4_EXT_MARK_UNWRIT2 and EXT4_EXT_DATA_VALID2
    flags set, and it calls ext4_split_extent_at() to split the second half
    with EXT4_EXT_DATA_VALID2, EXT4_EXT_MARK_UNWRIT1, EXT4_EXT_MAY_ZEROOUT
    and EXT4_EXT_MARK_UNWRIT2 flags set. However, ext4_split_extent_at()
    failed to insert extent since a temporary lack -ENOSPC. It zeroes out
    the first half but convert the entire on-disk extent to written since
    the EXT4_EXT_DATA_VALID2 flag set, but left the second half as unwritten
    in the extent status tree.

       [0000000000SSSSSS]  data                S: stale data, 0: zeroed
       [WWWWWWWWWWWWWWWW]  on-disk extent      W: written extent
       [WWWWWWWWWWUUUUUU]  extent status tree

    Finally, if the DIO failed to write data to the disk, the stale data in
    the second half will be exposed once the cached extent entry is gone.

    Fix this issue by not passing EXT4_GET_BLOCKS_CONVERT when splitting
    an unwritten extent before submitting I/O, and make
    ext4_split_convert_extents() to zero out the entire extent range
    to zero for this case, and also mark the extent in the extent status
    tree for consistency.

Tenable has extracted the preceding description block directly from the Unity Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.");
  # https://src.uniontech.com/#/security_advisory_detail?utsa_id=UTSA-2026-099951
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?a3240f72");
  # https://lore.kernel.org/linux-cve-announce/2026052739-CVE-2026-45985-6195@gregkh
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?72cf7a06");
  script_set_attribute(attribute:"see_also", value:"https://nvd.nist.gov/vuln/detail/CVE-2026-45985");
  script_set_attribute(attribute:"solution", value:
"Update the affected kernel package.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:S/C:N/I:N/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-45985");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/04/23");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/08/13");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/08/17");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Unity Linux Local Security Checks");

  script_copyright(english:"This script is Copyright (C) 2026 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info2.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/UOS-Server/release", "Host/UOS-Server/rpm-list", "Host/cpu");

  exit(0);
}
include('rpm2.inc');

if (!get_kb_item('Host/local_checks_enabled')) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_product = get_kb_item('installed_os/local/SSH/0/product');
if (isnull(os_product) || 'UOS Server' >!< os_product) audit(AUDIT_OS_NOT, 'UOS Server');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'UOS Server');
if (! preg(pattern:"^20.1050e([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'UOS Server 20.1050e', 'UOS Server ' + os_version);

if (!get_kb_item('Host/UOS-Server/rpm-list')) audit(AUDIT_PACKAGE_LIST_MISSING);

var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('aarch64' >!< cpu && 'amd64' >!< cpu && 'x86_64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'UOS Server', cpu);


var constraints = [
  {
    'release': '20',
    'sp': '1050e',
    'pkgs': [
      {'reference':'kernel-5.10.0-27.18.uel20', 'sp':'1050e', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-5.10.0-27.18.uel20', 'sp':'1050e', 'cpu':'amd64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-5.10.0-27.18.uel20', 'sp':'1050e', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE}
    ]
  }
];

var os_release = get_one_kb_item('installed_os/local/SSH/0/release');
var os_sp = get_one_kb_item('Host/*/minor_release');

var flag = 0;
var reference;
var sp;
var _cpu;
var el_string;
var rpm_spec_vers_cmp;
var epoch;
var allowmaj;
var exists_check;
var cves;
foreach var constraint ( constraints ) {
  # Check that the target release is equal to the affected release
  if (!empty_or_null(constraint['release'])){
    if (constraint['release'] != os_release) continue;
  }
  if (!empty_or_null(constraint['sp'])){
    if (constraint['sp'] != os_sp) continue;
  }
  foreach var pkg ( constraint['pkgs'] ) {
    reference = NULL;
    sp = NULL;
    _cpu = NULL;
    el_string = NULL;
    rpm_spec_vers_cmp = NULL;
    epoch = NULL;
    allowmaj = NULL;
    exists_check = NULL;
    cves = NULL;
    if (!empty_or_null(pkg['reference'])) reference = pkg['reference'];
    if (!empty_or_null(pkg['sp'])) sp = pkg['sp'];
    if (!empty_or_null(pkg['cpu'])) _cpu = pkg['cpu'];
    if (!empty_or_null(pkg['el_string'])) el_string = pkg['el_string'];
    if (!empty_or_null(pkg['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = pkg['rpm_spec_vers_cmp'];
    if (!empty_or_null(pkg['epoch'])) epoch = pkg['epoch'];
    if (!empty_or_null(pkg['allowmaj'])) allowmaj = pkg['allowmaj'];
    if (!empty_or_null(pkg['exists_check'])) exists_check = pkg['exists_check'];
    if (!empty_or_null(pkg['cves'])) cves = pkg['cves'];
    if (reference &&
        ## (no known rpm to check OR known rpm_exists)
        (!exists_check || rpm_exists(rpm:exists_check)) &&
        rpm_check(sp:sp, cpu:_cpu, reference:reference, epoch:epoch, el_string:el_string, rpm_spec_vers_cmp:rpm_spec_vers_cmp, allowmaj:allowmaj, cves:cves)) flag++;
  }
}


if (flag)
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_WARNING,
      extra      : rpm_report_get()
  );
  exit(0);
}
else
{
  var tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'kernel');
}