Unity Linux 20.1050e Security Update: kernel (UTSA-2026-100120)

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

include('compat.inc');

if (description)
{
  script_id(336882);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/08/17");

  script_cve_id("CVE-2026-53040");

  script_name(english:"Unity Linux 20.1050e Security Update: kernel (UTSA-2026-100120)");

  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-2026-100120 advisory.

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

    ocfs2: validate bg_bits during freefrag scan

    [BUG]
    A crafted filesystem can trigger an out-of-bounds bitmap walk when
    OCFS2_IOC_INFO is issued with OCFS2_INFO_FL_NON_COHERENT.

    BUG: KASAN: use-after-free in instrument_atomic_read include/linux/instrumented.h:68 [inline]
    BUG: KASAN: use-after-free in _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
    BUG: KASAN: use-after-free in test_bit_le include/asm-generic/bitops/le.h:21 [inline]
    BUG: KASAN: use-after-free in ocfs2_info_freefrag_scan_chain fs/ocfs2/ioctl.c:495 [inline]
    BUG: KASAN: use-after-free in ocfs2_info_freefrag_scan_bitmap fs/ocfs2/ioctl.c:588 [inline]
    BUG: KASAN: use-after-free in ocfs2_info_handle_freefrag fs/ocfs2/ioctl.c:662 [inline]
    BUG: KASAN: use-after-free in ocfs2_info_handle_request+0x1c66/0x3370 fs/ocfs2/ioctl.c:754
    Read of size 8 at addr ffff888031bce000 by task syz.0.636/1435
    Call Trace:
     __dump_stack lib/dump_stack.c:94 [inline]
     dump_stack_lvl+0xbe/0x130 lib/dump_stack.c:120
     print_address_description mm/kasan/report.c:378 [inline]
     print_report+0xd1/0x650 mm/kasan/report.c:482
     kasan_report+0xfb/0x140 mm/kasan/report.c:595
     check_region_inline mm/kasan/generic.c:186 [inline]
     kasan_check_range+0x11c/0x200 mm/kasan/generic.c:200
     __kasan_check_read+0x11/0x20 mm/kasan/shadow.c:31
     instrument_atomic_read include/linux/instrumented.h:68 [inline]
     _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
     test_bit_le include/asm-generic/bitops/le.h:21 [inline]
     ocfs2_info_freefrag_scan_chain fs/ocfs2/ioctl.c:495 [inline]
     ocfs2_info_freefrag_scan_bitmap fs/ocfs2/ioctl.c:588 [inline]
     ocfs2_info_handle_freefrag fs/ocfs2/ioctl.c:662 [inline]
     ocfs2_info_handle_request+0x1c66/0x3370 fs/ocfs2/ioctl.c:754
     ocfs2_info_handle+0x18d/0x2a0 fs/ocfs2/ioctl.c:828
     ocfs2_ioctl+0x632/0x6e0 fs/ocfs2/ioctl.c:913
     vfs_ioctl fs/ioctl.c:51 [inline]
     __do_sys_ioctl fs/ioctl.c:597 [inline]
     __se_sys_ioctl fs/ioctl.c:583 [inline]
     __x64_sys_ioctl+0x197/0x1e0 fs/ioctl.c:583
     ...

    [CAUSE]
    ocfs2_info_freefrag_scan_chain() uses on-disk bg_bits directly as the
    bitmap scan limit. The coherent path reads group descriptors through
    ocfs2_read_group_descriptor(), which validates the descriptor before
    use. The non-coherent path uses ocfs2_read_blocks_sync() instead and
    skips that validation, so an impossible bg_bits value can drive the
    bitmap walk past the end of the block.

    [FIX]
    Compute the bitmap capacity from the filesystem format with
    ocfs2_group_bitmap_size(), report descriptors whose bg_bits exceeds
    that limit, and clamp the scan to the computed capacity. This keeps the
    freefrag report going while avoiding reads beyond the buffer.

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-2026-100120
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?72de78b1");
  # https://lore.kernel.org/linux-cve-announce/2026062456-CVE-2026-53040-e3ea@gregkh
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?ee94342c");
  script_set_attribute(attribute:"see_also", value:"https://nvd.nist.gov/vuln/detail/CVE-2026-53040");
  script_set_attribute(attribute:"solution", value:
"Update the affected kernel package.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:S/C:C/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:H/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-2026-53040");

  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:"2026/06/24");
  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');
}