Unity Linux 20.1050a Security Update: kernel (UTSA-2026-053298)

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

include('compat.inc');

if (description)
{
  script_id(343219);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/06");

  script_cve_id("CVE-2025-22058");

  script_name(english:"Unity Linux 20.1050a Security Update: kernel (UTSA-2026-053298)");

  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-2026-053298 advisory.

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

    udp: Fix memory accounting leak.

    Matt Dowling reported a weird UDP memory usage issue.

    Under normal operation, the UDP memory usage reported in /proc/net/sockstat
    remains close to zero.  However, it occasionally spiked to 524,288 pages
    and never dropped.  Moreover, the value doubled when the application was
    terminated.  Finally, it caused intermittent packet drops.

    We can reproduce the issue with the script below [0]:

      1. /proc/net/sockstat reports 0 pages

        # cat /proc/net/sockstat | grep UDP:
        UDP: inuse 1 mem 0

      2. Run the script till the report reaches 524,288

        # python3 test.py & sleep 5
        # cat /proc/net/sockstat | grep UDP:
        UDP: inuse 3 mem 524288  <-- (INT_MAX + 1) >> PAGE_SHIFT

      3. Kill the socket and confirm the number never drops

        # pkill python3 && sleep 5
        # cat /proc/net/sockstat | grep UDP:
        UDP: inuse 1 mem 524288

      4. (necessary since v6.0) Trigger proto_memory_pcpu_drain()

        # python3 test.py & sleep 1 && pkill python3

      5. The number doubles

        # cat /proc/net/sockstat | grep UDP:
        UDP: inuse 1 mem 1048577

    The application set INT_MAX to SO_RCVBUF, which triggered an integer
    overflow in udp_rmem_release().

    When a socket is close()d, udp_destruct_common() purges its receive
    queue and sums up skb->truesize in the queue.  This total is calculated
    and stored in a local unsigned integer variable.

    The total size is then passed to udp_rmem_release() to adjust memory
    accounting.  However, because the function takes a signed integer
    argument, the total size can wrap around, causing an overflow.

    Then, the released amount is calculated as follows:

      1) Add size to sk->sk_forward_alloc.
      2) Round down sk->sk_forward_alloc to the nearest lower multiple of
          PAGE_SIZE and assign it to amount.
      3) Subtract amount from sk->sk_forward_alloc.
      4) Pass amount >> PAGE_SHIFT to __sk_mem_reduce_allocated().

    When the issue occurred, the total in udp_destruct_common() was 2147484480
    (INT_MAX + 833), which was cast to -2147482816 in udp_rmem_release().

    At 1) sk->sk_forward_alloc is changed from 3264 to -2147479552, and
    2) sets -2147479552 to amount.  3) reverts the wraparound, so we don't
    see a warning in inet_sock_destruct().  However, udp_memory_allocated
    ends up doubling at 4).

    Since commit 3cd3399dd7a8 (net: implement per-cpu reserves for
    memory_allocated), memory usage no longer doubles immediately after
    a socket is close()d because __sk_mem_reduce_allocated() caches the
    amount in udp_memory_per_cpu_fw_alloc.  However, the next time a UDP
    socket receives a packet, the subtraction takes effect, causing UDP
    memory usage to double.

    This issue makes further memory allocation fail once the socket's
    sk->sk_rmem_alloc exceeds net.ipv4.udp_rmem_min, resulting in packet
    drops.

    To prevent this issue, let's use unsigned int for the calculation and
    call sk_forward_alloc_add() only once for the small delta.

    Note that first_packet_length() also potentially has the same problem.

    [0]:
    from socket import *

    SO_RCVBUFFORCE = 33
    INT_MAX = (2 ** 31) - 1

    s = socket(AF_INET, SOCK_DGRAM)
    s.bind(('', 0))
    s.setsockopt(SOL_SOCKET, SO_RCVBUFFORCE, INT_MAX)

    c = socket(AF_INET, SOCK_DGRAM)
    c.connect(s.getsockname())

    data = b'a' * 100

    while True:
        c.send(data)

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-2026-053298
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?7171eefe");
  # https://lore.kernel.org/linux-cve-announce/2025041606-CVE-2025-22058-045a@gregkh
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?ec33a384");
  script_set_attribute(attribute:"see_also", value:"https://nvd.nist.gov/vuln/detail/CVE-2025-22058");
  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-2025-22058");

  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:"2025/04/16");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/07/27");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/06");

  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:"^(20.1050a)([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'UOS Server 20.1050a', '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 && 'loongarch64' >!< cpu && 'x86_64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'UOS Server', cpu);


var constraints = [
  {
    'release': '20',
    'sp': '1050a',
    'pkgs': [
      {'reference':'kernel-4.19.0-91.82.132.24.uelc20', 'sp':'1050a', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.0-91.82.132.24.uelc20', 'sp':'1050a', 'cpu':'amd64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.0-91.82.132.24.uelc20', 'sp':'1050a', 'cpu':'loongarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.0-91.82.132.24.uelc20', 'sp':'1050a', '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');
}