Unity Linux 20.1050e Security Update: kernel (UTSA-2026-099779)

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

include('compat.inc');

if (description)
{
  script_id(336752);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/08/17");

  script_cve_id("CVE-2026-63796");

  script_name(english:"Unity Linux 20.1050e Security Update: kernel (UTSA-2026-099779)");

  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-2026-099779 advisory.

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

    ocfs2: reject oversized group bitmap descriptors

    ocfs2_validate_gd_parent() only bounds bg_bits against the parent
    allocator's chain geometry.  A malicious descriptor can still claim a
    bg_size/bg_bits pair that exceeds the bitmap bytes that physically fit in
    the group descriptor block, so later bitmap scans and bit updates can run
    past bg_bitmap.

    Add a physical-cap check based on ocfs2_group_bitmap_size() for the parent
    allocator type and reject descriptors whose bg_size or bg_bits exceed that
    capacity.  Keep the existing chain geometry check so both the on-disk
    bitmap layout and the allocator metadata must agree before the descriptor
    is used.

    Validation reproduced this kernel report:
    KASAN use-after-free in _find_next_bit+0x7f/0xc0
    Read of size 8
    Call trace:
      dump_stack_lvl+0x66/0xa0 (?:?)
      print_report+0xd0/0x630 (?:?)
      _find_next_bit+0x7f/0xc0 (?:?)
      srso_alias_return_thunk+0x5/0xfbef5 (?:?)
      __virt_addr_valid+0x188/0x2f0 (?:?)
      kasan_report+0xe4/0x120 (?:?)
      ocfs2_find_max_contig_free_bits+0x35/0x70 (fs/ocfs2/suballoc.c:1375)
      ocfs2_block_group_set_bits+0x472/0x4b0 (fs/ocfs2/suballoc.c:1457)
      ocfs2_cluster_group_search+0x16b/0x440 (fs/ocfs2/suballoc.c:86)
      ocfs2_bg_discontig_fix_result+0x1ef/0x230 (fs/ocfs2/suballoc.c:1786)
      ocfs2_search_chain+0x8f8/0x10a0 (fs/ocfs2/suballoc.c:1886)
      get_page_from_freelist+0x70e/0x2370 (?:?)
      lock_release+0xc6/0x290 (?:?)
      do_raw_spin_unlock+0x9a/0x100 (?:?)
      kasan_unpoison+0x27/0x60 (?:?)
      __bfs+0x147/0x240 (?:?)
      get_page_from_freelist+0x83d/0x2370 (?:?)
      ocfs2_claim_suballoc_bits+0x38c/0xe70 (fs/ocfs2/suballoc.c:96)
      sched_domains_numa_masks_clear+0x70/0xd0 (?:?)
      check_irq_usage+0xe8/0xb70 (?:?)
      __ocfs2_claim_clusters+0x18d/0x4c0 (fs/ocfs2/suballoc.c:2497)
      check_path+0x24/0x50 (?:?)
      rcu_is_watching+0x20/0x50 (?:?)
      check_prev_add+0xfd/0xd00 (?:?)
      ocfs2_add_clusters_in_btree+0x17d/0x810 (fs/ocfs2/suballoc.c:?)
      __folio_batch_add_and_move+0x1f5/0x3d0 (?:?)
      ocfs2_add_inode_data+0xd9/0x120 (fs/ocfs2/suballoc.c:?)
      filemap_add_folio+0x105/0x1f0 (?:?)
      ocfs2_write_begin_nolock+0x29f7/0x2f80 (fs/ocfs2/suballoc.c:3043)
      ocfs2_read_inode_block+0xb5/0x110 (fs/ocfs2/suballoc.c:?)
      down_write+0xf5/0x180 (?:?)
      ocfs2_write_begin+0x180/0x240 (fs/ocfs2/suballoc.c:?)
      __mark_inode_dirty+0x758/0x9a0 (?:?)
      inode_to_bdi+0x41/0x90 (?:?)
      balance_dirty_pages_ratelimited_flags+0xf8/0x1d0 (?:?)
      generic_perform_write+0x252/0x440 (?:?)
      mnt_put_write_access_file+0x16/0x70 (?:?)
      file_update_time_flags+0xe4/0x200 (?:?)
      ocfs2_file_write_iter+0x80a/0x1320 (fs/ocfs2/suballoc.c:?)
      lock_acquire+0x184/0x2f0 (?:?)
      ksys_write+0xd2/0x170 (?:?)
      apparmor_file_permission+0xf5/0x310 (?:?)
      read_zero+0x8d/0x140 (?:?)
      lock_is_held_type+0x8f/0x100 (?:?)

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-2026-099779
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?47a8a224");
  # https://lore.kernel.org/linux-cve-announce/2026071900-CVE-2026-63796-9a88@gregkh
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?6e82f9c7");
  script_set_attribute(attribute:"see_also", value:"https://nvd.nist.gov/vuln/detail/CVE-2026-63796");
  script_set_attribute(attribute:"solution", value:
"Update the affected kernel package.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:S/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/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-2026-63796");

  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:"2026/07/08");
  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_HOLE,
      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');
}