Unity Linux 20.1070e Security Update: kernel (UTSA-2025-986880)

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

include('compat.inc');

if (description)
{
  script_id(269032);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2025/10/15");

  script_cve_id("CVE-2021-47637");

  script_name(english:"Unity Linux 20.1070e Security Update: kernel (UTSA-2025-986880)");

  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-2025-986880 advisory.

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

    ubifs: Fix deadlock in concurrent rename whiteout and inode writeback

    Following hung tasks:
    [   77.028764] task:kworker/u8:4    state:D stack:    0 pid:  132
    [   77.028820] Call Trace:
    [   77.029027]  schedule+0x8c/0x1b0
    [   77.029067]  mutex_lock+0x50/0x60
    [   77.029074]  ubifs_write_inode+0x68/0x1f0 [ubifs]
    [   77.029117]  __writeback_single_inode+0x43c/0x570
    [   77.029128]  writeback_sb_inodes+0x259/0x740
    [   77.029148]  wb_writeback+0x107/0x4d0
    [   77.029163]  wb_workfn+0x162/0x7b0

    [   92.390442] task:aa              state:D stack:    0 pid: 1506
    [   92.390448] Call Trace:
    [   92.390458]  schedule+0x8c/0x1b0
    [   92.390461]  wb_wait_for_completion+0x82/0xd0
    [   92.390469]  __writeback_inodes_sb_nr+0xb2/0x110
    [   92.390472]  writeback_inodes_sb_nr+0x14/0x20
    [   92.390476]  ubifs_budget_space+0x705/0xdd0 [ubifs]
    [   92.390503]  do_rename.cold+0x7f/0x187 [ubifs]
    [   92.390549]  ubifs_rename+0x8b/0x180 [ubifs]
    [   92.390571]  vfs_rename+0xdb2/0x1170
    [   92.390580]  do_renameat2+0x554/0x770

    , are caused by concurrent rename whiteout and inode writeback processes:
            rename_whiteout(Thread 1)               wb_workfn(Thread2)
    ubifs_rename
      do_rename
        lock_4_inodes (Hold ui_mutex)
        ubifs_budget_space
          make_free_space
            shrink_liability
              __writeback_inodes_sb_nr
                bdi_split_work_to_wbs (Queue new wb work)
                                                  wb_do_writeback(wb work)
                                                    __writeback_single_inode
                                                      ubifs_write_inode
                                                        LOCK(ui_mutex)
                                                               
                  wb_wait_for_completion (Wait wb work) <-- deadlock!

    Reproducer (Detail program in [Link]):
      1. SYS_renameat2(/mp/dir/file, /mp/dir/whiteout, RENAME_WHITEOUT)
      2. Consume out of space before kernel(mdelay) doing budget for whiteout

    Fix it by doing whiteout space budget before locking ubifs inodes.
    BTW, it also fixes wrong goto tag 'out_release' in whiteout budget
    error handling path(It should at least recover dir i_size and unlock
    4 ubifs inodes).

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-2025-986880
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?5dc9532b");
  # https://lore.kernel.org/linux-cve-announce/2025022646-CVE-2021-47637-c754@gregkh
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?53e21d72");
  script_set_attribute(attribute:"see_also", value:"https://nvd.nist.gov/vuln/detail/CVE-2021-47637");
  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-2021-47637");

  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:"2025/02/26");
  script_set_attribute(attribute:"patch_publication_date", value:"2025/09/23");
  script_set_attribute(attribute:"plugin_publication_date", value:"2025/10/07");

  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) 2025 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:"^20.1070e([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'UOS Server 20.1070e', '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': '1070e',
    'pkgs': [
      {'reference':'kernel-5.10.0-74.16', 'sp':'1070e', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-5.10.0-74.16', 'sp':'1070e', 'cpu':'amd64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-5.10.0-74.16', 'sp':'1070e', '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');
}