Azure Linux 3.0 Security Update: kernel (CVE-2025-21866)

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

include('compat.inc');

if (description)
{
  script_id(296199);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/01/22");

  script_cve_id("CVE-2025-21866");

  script_name(english:"Azure Linux 3.0 Security Update: kernel (CVE-2025-21866)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Azure Linux host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The version of kernel installed on the remote Azure Linux 3.0 host is prior to tested version. It is, therefore,
affected by a vulnerability as referenced in the CVE-2025-21866 advisory.

  - In the Linux kernel, the following vulnerability has been resolved: powerpc/code-patching: Fix KASAN hit
    by not flagging text patching area as VM_ALLOC Erhard reported the following KASAN hit while booting his
    PowerMac G4 with a KASAN-enabled kernel 6.13-rc6: BUG: KASAN: vmalloc-out-of-bounds in
    copy_to_kernel_nofault+0xd8/0x1c8 Write of size 8 at addr f1000000 by task chronyd/1293 CPU: 0 UID: 123
    PID: 1293 Comm: chronyd Tainted: G W 6.13.0-rc6-PMacG4 #2 Tainted: [W]=WARN Hardware name: PowerMac3,6
    7455 0x80010303 PowerMac Call Trace: [c2437590] [c1631a84] dump_stack_lvl+0x70/0x8c (unreliable)
    [c24375b0] [c0504998] print_report+0xdc/0x504 [c2437610] [c050475c] kasan_report+0xf8/0x108 [c2437690]
    [c0505a3c] kasan_check_range+0x24/0x18c [c24376a0] [c03fb5e4] copy_to_kernel_nofault+0xd8/0x1c8 [c24376c0]
    [c004c014] patch_instructions+0x15c/0x16c [c2437710] [c00731a8] bpf_arch_text_copy+0x60/0x7c [c2437730]
    [c0281168] bpf_jit_binary_pack_finalize+0x50/0xac [c2437750] [c0073cf4] bpf_int_jit_compile+0xb30/0xdec
    [c2437880] [c0280394] bpf_prog_select_runtime+0x15c/0x478 [c24378d0] [c1263428]
    bpf_prepare_filter+0xbf8/0xc14 [c2437990] [c12677ec] bpf_prog_create_from_user+0x258/0x2b4 [c24379d0]
    [c027111c] do_seccomp+0x3dc/0x1890 [c2437ac0] [c001d8e0] system_call_exception+0x2dc/0x420 [c2437f30]
    [c00281ac] ret_from_syscall+0x0/0x2c --- interrupt: c00 at 0x5a1274 NIP: 005a1274 LR: 006a3b3c CTR:
    005296c8 REGS: c2437f40 TRAP: 0c00 Tainted: G W (6.13.0-rc6-PMacG4) MSR: 0200f932
    <VEC,EE,PR,FP,ME,IR,DR,RI> CR: 24004422 XER: 00000000 GPR00: 00000166 af8f3fa0 a7ee3540 00000001 00000000
    013b6500 005a5858 0200f932 GPR08: 00000000 00001fe9 013d5fc8 005296c8 2822244c 00b2fcd8 00000000 af8f4b57
    GPR16: 00000000 00000001 00000000 00000000 00000000 00000001 00000000 00000002 GPR24: 00afdbb0 00000000
    00000000 00000000 006e0004 013ce060 006e7c1c 00000001 NIP [005a1274] 0x5a1274 LR [006a3b3c] 0x6a3b3c ---
    interrupt: c00 The buggy address belongs to the virtual mapping at [f1000000, f1002000) created by:
    text_area_cpu_up+0x20/0x190 The buggy address belongs to the physical page: page: refcount:1 mapcount:0
    mapping:00000000 index:0x0 pfn:0x76e30 flags: 0x80000000(zone=2) raw: 80000000 00000000 00000122 00000000
    00000000 00000000 ffffffff 00000001 raw: 00000000 page dumped because: kasan: bad access detected Memory
    state around the buggy address: f0ffff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f0ffff80: 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 >f1000000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ^
    f1000080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f1000100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
    f8 f8 f8 ================================================================== f8 corresponds to
    KASAN_VMALLOC_INVALID which means the area is not initialised hence not supposed to be used yet. Powerpc
    text patching infrastructure allocates a virtual memory area using get_vm_area() and flags it as VM_ALLOC.
    But that flag is meant to be used for vmalloc() and vmalloc() allocated memory is not supposed to be used
    before a call to __vmalloc_node_range() which is never called for that area. That went undetected until
    commit e4137f08816b (mm, kasan, kmsan: instrument copy_from/to_kernel_nofault) The area allocated by
    text_area_cpu_up() is not vmalloc memory, it is mapped directly on demand when needed by
    map_kernel_page(). There is no VM flag corresponding to such usage, so just pass no flag. That way the
    area will be unpoisonned and usable immediately. (CVE-2025-21866)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.");
  script_set_attribute(attribute:"see_also", value:"https://nvd.nist.gov/vuln/detail/CVE-2025-21866");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  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-2025-21866");

  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:"2025/03/12");
  script_set_attribute(attribute:"patch_publication_date", value:"2025/04/08");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/01/22");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:microsoft:azure_linux:bpftool");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:microsoft:azure_linux:kernel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:microsoft:azure_linux:kernel-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:microsoft:azure_linux:kernel-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:microsoft:azure_linux:kernel-docs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:microsoft:azure_linux:kernel-drivers-accessibility");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:microsoft:azure_linux:kernel-drivers-gpu");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:microsoft:azure_linux:kernel-drivers-intree-amdgpu");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:microsoft:azure_linux:kernel-drivers-sound");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:microsoft:azure_linux:kernel-tools");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:microsoft:azure_linux:python3-perf");
  script_set_attribute(attribute:"cpe", value:"x-cpe:/o:microsoft:azure_linux");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Azure 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/AzureLinux/release", "Host/AzureLinux/rpm-list", "Host/cpu");

  exit(0);
}
include('rpm.inc');

if (!get_kb_item('Host/local_checks_enabled')) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var release = get_kb_item('Host/AzureLinux/release');
if (isnull(release) || 'Azure Linux' >!< release) audit(AUDIT_OS_NOT, 'Azure Linux');
var os_ver = pregmatch(pattern: "Azure Linux ([0-9]+(\.[0-9]+)?)", string:release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, 'Azure Linux');
os_ver = os_ver[1];
if (! preg(pattern:"^3([^0-9]|$)", string:os_ver)) audit(AUDIT_OS_NOT, 'Azure Linux 3.0', 'Azure Linux ' + os_ver);

if (!get_kb_item('Host/AzureLinux/rpm-list')) audit(AUDIT_PACKAGE_LIST_MISSING);

var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('x86_64' >!< cpu && cpu !~ "^i[3-6]86$" && 'aarch64' >!< cpu)
  audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Azure Linux', cpu);

var pkgs = [
    {'reference':'bpftool-6.6.82.1-1.azl3', 'cpu':'aarch64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'bpftool-6.6.82.1-1.azl3', 'cpu':'x86_64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-6.6.82.1-1.azl3', 'cpu':'aarch64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-6.6.82.1-1.azl3', 'cpu':'x86_64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-debuginfo-6.6.82.1-1.azl3', 'cpu':'aarch64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-debuginfo-6.6.82.1-1.azl3', 'cpu':'x86_64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-devel-6.6.82.1-1.azl3', 'cpu':'aarch64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-devel-6.6.82.1-1.azl3', 'cpu':'x86_64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-docs-6.6.82.1-1.azl3', 'cpu':'aarch64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-docs-6.6.82.1-1.azl3', 'cpu':'x86_64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-drivers-accessibility-6.6.82.1-1.azl3', 'cpu':'aarch64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-drivers-accessibility-6.6.82.1-1.azl3', 'cpu':'x86_64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-drivers-gpu-6.6.82.1-1.azl3', 'cpu':'aarch64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-drivers-gpu-6.6.82.1-1.azl3', 'cpu':'x86_64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-drivers-intree-amdgpu-6.6.82.1-1.azl3', 'cpu':'aarch64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-drivers-intree-amdgpu-6.6.82.1-1.azl3', 'cpu':'x86_64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-drivers-sound-6.6.82.1-1.azl3', 'cpu':'aarch64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-drivers-sound-6.6.82.1-1.azl3', 'cpu':'x86_64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-tools-6.6.82.1-1.azl3', 'cpu':'aarch64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'kernel-tools-6.6.82.1-1.azl3', 'cpu':'x86_64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'python3-perf-6.6.82.1-1.azl3', 'cpu':'aarch64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'python3-perf-6.6.82.1-1.azl3', 'cpu':'x86_64', 'release':'3.0', 'rpm_spec_vers_cmp':TRUE}
];

var flag = 0;
foreach var package_array ( pkgs ) {
  var reference = NULL;
  var _release = NULL;
  var sp = NULL;
  var _cpu = NULL;
  var el_string = NULL;
  var rpm_spec_vers_cmp = NULL;
  var epoch = NULL;
  var allowmaj = NULL;
  var exists_check = NULL;
  var cves = NULL;
  if (!empty_or_null(package_array['reference'])) reference = package_array['reference'];
  if (!empty_or_null(package_array['release'])) _release = 'Azure Linux ' + package_array['release'];
  if (!empty_or_null(package_array['sp'])) sp = package_array['sp'];
  if (!empty_or_null(package_array['cpu'])) _cpu = package_array['cpu'];
  if (!empty_or_null(package_array['el_string'])) el_string = package_array['el_string'];
  if (!empty_or_null(package_array['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = package_array['rpm_spec_vers_cmp'];
  if (!empty_or_null(package_array['epoch'])) epoch = package_array['epoch'];
  if (!empty_or_null(package_array['allowmaj'])) allowmaj = package_array['allowmaj'];
  if (!empty_or_null(package_array['exists_check'])) exists_check = package_array['exists_check'];
  if (!empty_or_null(package_array['cves'])) cves = package_array['cves'];
  if (reference && _release && (!exists_check || rpm_exists(release:_release, rpm:exists_check))) {
    if (rpm_check(release:_release, 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, 'bpftool / kernel / kernel-debuginfo / kernel-devel / kernel-docs / etc');
}