Unity Linux 20.1050e Security Update: kernel (UTSA-2026-021528)

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

include('compat.inc');

if (description)
{
  script_id(315893);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/05/20");

  script_cve_id("CVE-2022-50335");

  script_name(english:"Unity Linux 20.1050e Security Update: kernel (UTSA-2026-021528)");

  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-2026-021528 advisory.

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

    9p: set req refcount to zero to avoid uninitialized usage

    When a new request is allocated, the refcount will be zero if it is
    reused, but if the request is newly allocated from slab, it is not fully
    initialized before being added to idr.

    If the p9_read_work got a response before the refcount initiated. It will
    use a uninitialized req, which will result in a bad request data struct.

    Here is the logs from syzbot.

    Corrupted memory at 0xffff88807eade00b [ 0xff 0x07 0x00 0x00 0x00 0x00
    0x00 0x00 . . . . . . . . ] (in kfence-#110):
     p9_fcall_fini net/9p/client.c:248 [inline]
     p9_req_put net/9p/client.c:396 [inline]
     p9_req_put+0x208/0x250 net/9p/client.c:390
     p9_client_walk+0x247/0x540 net/9p/client.c:1165
     clone_fid fs/9p/fid.h:21 [inline]
     v9fs_fid_xattr_set+0xe4/0x2b0 fs/9p/xattr.c:118
     v9fs_xattr_set fs/9p/xattr.c:100 [inline]
     v9fs_xattr_handler_set+0x6f/0x120 fs/9p/xattr.c:159
     __vfs_setxattr+0x119/0x180 fs/xattr.c:182
     __vfs_setxattr_noperm+0x129/0x5f0 fs/xattr.c:216
     __vfs_setxattr_locked+0x1d3/0x260 fs/xattr.c:277
     vfs_setxattr+0x143/0x340 fs/xattr.c:309
     setxattr+0x146/0x160 fs/xattr.c:617
     path_setxattr+0x197/0x1c0 fs/xattr.c:636
     __do_sys_setxattr fs/xattr.c:652 [inline]
     __se_sys_setxattr fs/xattr.c:648 [inline]
     __ia32_sys_setxattr+0xc0/0x160 fs/xattr.c:648
     do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
     __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178
     do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
     entry_SYSENTER_compat_after_hwframe+0x70/0x82

    Below is a similar scenario, the scenario in the syzbot log looks more
    complicated than this one, but this patch can fix it.

         T21124                   p9_read_work
    ======================== second trans =================================
    p9_client_walk
      p9_client_rpc
        p9_client_prepare_req
          p9_tag_alloc
            req = kmem_cache_alloc(p9_req_cache, GFP_NOFS);
            tag = idr_alloc
            << preempted >>
            req->tc.tag = tag;
                                /* req->[refcount/tag] == uninitialized */
                                m->rreq = p9_tag_lookup(m->client, m->rc.tag);
                                  /* increments uninitalized refcount */

            refcount_set(&req->refcount, 2);
                                /* cb drops one ref */
                                p9_client_cb(req)
                                /* reader thread drops its ref:
                                   request is incorrectly freed */
                                p9_req_put(req)
        /* use after free and ref underflow */
        p9_req_put(req)

    To fix it, we can initialize the refcount to zero before add to idr.

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-2026-021528
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?e37bf10d");
  # https://lore.kernel.org/linux-cve-announce/2025091556-CVE-2022-50335-141b@gregkh
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?93ebda0d");
  script_set_attribute(attribute:"see_also", value:"https://nvd.nist.gov/vuln/detail/CVE-2022-50335");
  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-2022-50335");

  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:"2025/09/15");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/05/21");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/05/20");

  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-4.19.90-2211.5.0.0178.56.uel20', 'sp':'1050e', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.90-2211.5.0.0178.56.uel20', 'sp':'1050e', 'cpu':'amd64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.90-2211.5.0.0178.56.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');
}