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Ubuntu Security Notice (C) 2021-2024 Canonical, Inc. / NASL script (C) 2021-2024 and is owned by Tenable, Inc. or an Affiliate thereof.UBUNTU_USN-4948-1.NASL
HistoryMay 12, 2021 - 12:00 a.m.

Ubuntu 20.04 LTS : Linux kernel (OEM) vulnerabilities (USN-4948-1)

2021-05-1200:00:00
Ubuntu Security Notice (C) 2021-2024 Canonical, Inc. / NASL script (C) 2021-2024 and is owned by Tenable, Inc. or an Affiliate thereof.
www.tenable.com
59

8.8 High

AI Score

Confidence

Low

The remote Ubuntu 20.04 LTS host has a package installed that is affected by multiple vulnerabilities as referenced in the USN-4948-1 advisory.

  • A vulnerability was found in Linux Kernel where refcount leak in llcp_sock_bind() causing use-after-free which might lead to privilege escalations. (CVE-2020-25670)

  • A vulnerability was found in Linux Kernel, where a refcount leak in llcp_sock_connect() causing use-after- free which might lead to privilege escalations. (CVE-2020-25671)

  • A memory leak vulnerability was found in Linux kernel in llcp_sock_connect (CVE-2020-25672)

  • The fix for XSA-365 includes initialization of pointers such that subsequent cleanup code wouldn’t use uninitialized or stale values. This initialization went too far and may under certain conditions also overwrite pointers which are in need of cleaning up. The lack of cleanup would result in leaking persistent grants. The leak in turn would prevent fully cleaning up after a respective guest has died, leaving around zombie domains. All Linux versions having the fix for XSA-365 applied are vulnerable.
    XSA-365 was classified to affect versions back to at least 3.11. (CVE-2021-28688)

  • An issue was discovered in fs/io_uring.c in the Linux kernel through 5.11.8. It allows attackers to cause a denial of service (deadlock) because exit may be waiting to park a SQPOLL thread, but concurrently that SQPOLL thread is waiting for a signal to start, aka CID-3ebba796fa25. (CVE-2021-28951)

  • An issue was discovered in the Linux kernel through 5.11.8. The sound/soc/qcom/sdm845.c soundwire device driver has a buffer overflow when an unexpected port ID number is encountered, aka CID-1c668e1c0a0f. (This has been fixed in 5.12-rc4.) (CVE-2021-28952)

  • A race condition was discovered in get_old_root in fs/btrfs/ctree.c in the Linux kernel through 5.11.8. It allows attackers to cause a denial of service (BUG) because of a lack of locking on an extent buffer before a cloning operation, aka CID-dbcc7d57bffc. (CVE-2021-28964)

  • In intel_pmu_drain_pebs_nhm in arch/x86/events/intel/ds.c in the Linux kernel through 5.11.8 on some Haswell CPUs, userspace applications (such as perf-fuzzer) can cause a system crash because the PEBS status in a PEBS record is mishandled, aka CID-d88d05a9e0b6. (CVE-2021-28971)

  • In drivers/pci/hotplug/rpadlpar_sysfs.c in the Linux kernel through 5.11.8, the RPA PCI Hotplug driver has a user-tolerable buffer overflow when writing a new device name to the driver from userspace, allowing userspace to write data to the kernel stack frame directly. This occurs because add_slot_store and remove_slot_store mishandle drc_name ‘\0’ termination, aka CID-cc7a0bb058b8. (CVE-2021-28972)

  • An issue was discovered in the Linux kernel through 5.11.10. drivers/net/ethernet/freescale/gianfar.c in the Freescale Gianfar Ethernet driver allows attackers to cause a system crash because a negative fragment size is calculated in situations involving an rx queue overrun when jumbo packets are used and NAPI is enabled, aka CID-d8861bab48b6. (CVE-2021-29264)

  • An issue was discovered in the Linux kernel before 5.11.9. drivers/vhost/vdpa.c has a use-after-free because v->config_ctx has an invalid value upon re-opening a character device, aka CID-f6bbf0010ba0.
    (CVE-2021-29266)

  • An issue was discovered in the Linux kernel before 5.11.11. tipc_nl_retrieve_key in net/tipc/node.c does not properly validate certain data sizes, aka CID-0217ed2848e8. (CVE-2021-29646)

  • An issue was discovered in the Linux kernel before 5.11.11. qrtr_recvmsg in net/qrtr/qrtr.c allows attackers to obtain sensitive information from kernel memory because of a partially uninitialized data structure, aka CID-50535249f624. (CVE-2021-29647)

  • An issue was discovered in the Linux kernel before 5.11.11. The user mode driver (UMD) has a copy_process() memory leak, related to a lack of cleanup steps in kernel/usermode_driver.c and kernel/bpf/preload/bpf_preload_kern.c, aka CID-f60a85cad677. (CVE-2021-29649)

  • An issue was discovered in the Linux kernel before 5.11.11. The netfilter subsystem allows attackers to cause a denial of service (panic) because net/netfilter/x_tables.c and include/linux/netfilter/x_tables.h lack a full memory barrier upon the assignment of a new table value, aka CID-175e476b8cdf.
    (CVE-2021-29650)

  • arch/x86/kvm/svm/nested.c in the Linux kernel before 5.11.12 has a use-after-free in which an AMD KVM guest can bypass access control on host OS MSRs when there are nested guests, aka CID-a58d9166a756. This occurs because of a TOCTOU race condition associated with a VMCB12 double fetch in nested_svm_vmrun.
    (CVE-2021-29657)

  • An out-of-bounds (OOB) memory write flaw was found in list_devices in drivers/md/dm-ioctl.c in the Multi- device driver module in the Linux kernel before 5.12. A bound check failure allows an attacker with special user (CAP_SYS_ADMIN) privilege to gain access to out-of-bounds memory leading to a system crash or a leak of internal kernel information. The highest threat from this vulnerability is to system availability. (CVE-2021-31916)

  • A flaw was found in the Nosy driver in the Linux kernel. This issue allows a device to be inserted twice into a doubly-linked list, leading to a use-after-free when one of these devices is removed. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability. Versions before kernel 5.12-rc6 are affected (CVE-2021-3483)

  • The eBPF RINGBUF bpf_ringbuf_reserve() function in the Linux kernel did not check that the allocated size was smaller than the ringbuf size, allowing an attacker to perform out-of-bounds writes within the kernel and therefore, arbitrary code execution. This issue was fixed via commit 4b81ccebaeee (bpf, ringbuf: Deny reserve of buffers larger than ringbuf) (v5.13-rc4) and backported to the stable kernels in v5.12.4, v5.11.21, and v5.10.37. It was introduced via 457f44363a88 (bpf: Implement BPF ring buffer and verifier support for it) (v5.8-rc1). (CVE-2021-3489)

  • The eBPF ALU32 bounds tracking for bitwise ops (AND, OR and XOR) in the Linux kernel did not properly update 32-bit bounds, which could be turned into out of bounds reads and writes in the Linux kernel and therefore, arbitrary code execution. This issue was fixed via commit 049c4e13714e (bpf: Fix alu32 const subreg bound tracking on bitwise operations) (v5.13-rc4) and backported to the stable kernels in v5.12.4, v5.11.21, and v5.10.37. The AND/OR issues were introduced by commit 3f50f132d840 (bpf: Verifier, do explicit ALU32 bounds tracking) (5.7-rc1) and the XOR variant was introduced by 2921c90d4718 (bpf:Fix a verifier failure with xor) ( 5.10-rc1). (CVE-2021-3490)

  • The io_uring subsystem in the Linux kernel allowed the MAX_RW_COUNT limit to be bypassed in the PROVIDE_BUFFERS operation, which led to negative values being usedin mem_rw when reading /proc/<PID>/mem.
    This could be used to create a heap overflow leading to arbitrary code execution in the kernel. It was addressed via commit d1f82808877b (io_uring: truncate lengths larger than MAX_RW_COUNT on provide buffers) (v5.13-rc1) and backported to the stable kernels in v5.12.4, v5.11.21, and v5.10.37. It was introduced in ddf0322db79c (io_uring: add IORING_OP_PROVIDE_BUFFERS) (v5.7-rc1). (CVE-2021-3491)

Note that Nessus has not tested for these issues but has instead relied only on the application’s self-reported version number.

#%NASL_MIN_LEVEL 70300
##
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-4948-1. The text
# itself is copyright (C) Canonical, Inc. See
# <https://ubuntu.com/security/notices>. Ubuntu(R) is a registered
# trademark of Canonical, Inc.
##

include('deprecated_nasl_level.inc');
include('compat.inc');

if (description)
{
  script_id(149407);
  script_version("1.10");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/01/09");

  script_cve_id(
    "CVE-2020-25670",
    "CVE-2020-25671",
    "CVE-2020-25672",
    "CVE-2021-3483",
    "CVE-2021-3489",
    "CVE-2021-3490",
    "CVE-2021-3491",
    "CVE-2021-28688",
    "CVE-2021-28951",
    "CVE-2021-28952",
    "CVE-2021-28964",
    "CVE-2021-28971",
    "CVE-2021-28972",
    "CVE-2021-29264",
    "CVE-2021-29266",
    "CVE-2021-29646",
    "CVE-2021-29647",
    "CVE-2021-29649",
    "CVE-2021-29650",
    "CVE-2021-29657",
    "CVE-2021-31916"
  );
  script_xref(name:"USN", value:"4948-1");

  script_name(english:"Ubuntu 20.04 LTS : Linux kernel (OEM) vulnerabilities (USN-4948-1)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Ubuntu host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The remote Ubuntu 20.04 LTS host has a package installed that is affected by multiple vulnerabilities as referenced in
the USN-4948-1 advisory.

  - A vulnerability was found in Linux Kernel where refcount leak in llcp_sock_bind() causing use-after-free
    which might lead to privilege escalations. (CVE-2020-25670)

  - A vulnerability was found in Linux Kernel, where a refcount leak in llcp_sock_connect() causing use-after-
    free which might lead to privilege escalations. (CVE-2020-25671)

  - A memory leak vulnerability was found in Linux kernel in llcp_sock_connect (CVE-2020-25672)

  - The fix for XSA-365 includes initialization of pointers such that subsequent cleanup code wouldn't use
    uninitialized or stale values. This initialization went too far and may under certain conditions also
    overwrite pointers which are in need of cleaning up. The lack of cleanup would result in leaking
    persistent grants. The leak in turn would prevent fully cleaning up after a respective guest has died,
    leaving around zombie domains. All Linux versions having the fix for XSA-365 applied are vulnerable.
    XSA-365 was classified to affect versions back to at least 3.11. (CVE-2021-28688)

  - An issue was discovered in fs/io_uring.c in the Linux kernel through 5.11.8. It allows attackers to cause
    a denial of service (deadlock) because exit may be waiting to park a SQPOLL thread, but concurrently that
    SQPOLL thread is waiting for a signal to start, aka CID-3ebba796fa25. (CVE-2021-28951)

  - An issue was discovered in the Linux kernel through 5.11.8. The sound/soc/qcom/sdm845.c soundwire device
    driver has a buffer overflow when an unexpected port ID number is encountered, aka CID-1c668e1c0a0f. (This
    has been fixed in 5.12-rc4.) (CVE-2021-28952)

  - A race condition was discovered in get_old_root in fs/btrfs/ctree.c in the Linux kernel through 5.11.8. It
    allows attackers to cause a denial of service (BUG) because of a lack of locking on an extent buffer
    before a cloning operation, aka CID-dbcc7d57bffc. (CVE-2021-28964)

  - In intel_pmu_drain_pebs_nhm in arch/x86/events/intel/ds.c in the Linux kernel through 5.11.8 on some
    Haswell CPUs, userspace applications (such as perf-fuzzer) can cause a system crash because the PEBS
    status in a PEBS record is mishandled, aka CID-d88d05a9e0b6. (CVE-2021-28971)

  - In drivers/pci/hotplug/rpadlpar_sysfs.c in the Linux kernel through 5.11.8, the RPA PCI Hotplug driver has
    a user-tolerable buffer overflow when writing a new device name to the driver from userspace, allowing
    userspace to write data to the kernel stack frame directly. This occurs because add_slot_store and
    remove_slot_store mishandle drc_name '\0' termination, aka CID-cc7a0bb058b8. (CVE-2021-28972)

  - An issue was discovered in the Linux kernel through 5.11.10. drivers/net/ethernet/freescale/gianfar.c in
    the Freescale Gianfar Ethernet driver allows attackers to cause a system crash because a negative fragment
    size is calculated in situations involving an rx queue overrun when jumbo packets are used and NAPI is
    enabled, aka CID-d8861bab48b6. (CVE-2021-29264)

  - An issue was discovered in the Linux kernel before 5.11.9. drivers/vhost/vdpa.c has a use-after-free
    because v->config_ctx has an invalid value upon re-opening a character device, aka CID-f6bbf0010ba0.
    (CVE-2021-29266)

  - An issue was discovered in the Linux kernel before 5.11.11. tipc_nl_retrieve_key in net/tipc/node.c does
    not properly validate certain data sizes, aka CID-0217ed2848e8. (CVE-2021-29646)

  - An issue was discovered in the Linux kernel before 5.11.11. qrtr_recvmsg in net/qrtr/qrtr.c allows
    attackers to obtain sensitive information from kernel memory because of a partially uninitialized data
    structure, aka CID-50535249f624. (CVE-2021-29647)

  - An issue was discovered in the Linux kernel before 5.11.11. The user mode driver (UMD) has a
    copy_process() memory leak, related to a lack of cleanup steps in kernel/usermode_driver.c and
    kernel/bpf/preload/bpf_preload_kern.c, aka CID-f60a85cad677. (CVE-2021-29649)

  - An issue was discovered in the Linux kernel before 5.11.11. The netfilter subsystem allows attackers to
    cause a denial of service (panic) because net/netfilter/x_tables.c and include/linux/netfilter/x_tables.h
    lack a full memory barrier upon the assignment of a new table value, aka CID-175e476b8cdf.
    (CVE-2021-29650)

  - arch/x86/kvm/svm/nested.c in the Linux kernel before 5.11.12 has a use-after-free in which an AMD KVM
    guest can bypass access control on host OS MSRs when there are nested guests, aka CID-a58d9166a756. This
    occurs because of a TOCTOU race condition associated with a VMCB12 double fetch in nested_svm_vmrun.
    (CVE-2021-29657)

  - An out-of-bounds (OOB) memory write flaw was found in list_devices in drivers/md/dm-ioctl.c in the Multi-
    device driver module in the Linux kernel before 5.12. A bound check failure allows an attacker with
    special user (CAP_SYS_ADMIN) privilege to gain access to out-of-bounds memory leading to a system crash or
    a leak of internal kernel information. The highest threat from this vulnerability is to system
    availability. (CVE-2021-31916)

  - A flaw was found in the Nosy driver in the Linux kernel. This issue allows a device to be inserted twice
    into a doubly-linked list, leading to a use-after-free when one of these devices is removed. The highest
    threat from this vulnerability is to confidentiality, integrity, as well as system availability. Versions
    before kernel 5.12-rc6 are affected (CVE-2021-3483)

  - The eBPF RINGBUF bpf_ringbuf_reserve() function in the Linux kernel did not check that the allocated size
    was smaller than the ringbuf size, allowing an attacker to perform out-of-bounds writes within the kernel
    and therefore, arbitrary code execution. This issue was fixed via commit 4b81ccebaeee (bpf, ringbuf: Deny
    reserve of buffers larger than ringbuf) (v5.13-rc4) and backported to the stable kernels in v5.12.4,
    v5.11.21, and v5.10.37. It was introduced via 457f44363a88 (bpf: Implement BPF ring buffer and verifier
    support for it) (v5.8-rc1). (CVE-2021-3489)

  - The eBPF ALU32 bounds tracking for bitwise ops (AND, OR and XOR) in the Linux kernel did not properly
    update 32-bit bounds, which could be turned into out of bounds reads and writes in the Linux kernel and
    therefore, arbitrary code execution. This issue was fixed via commit 049c4e13714e (bpf: Fix alu32 const
    subreg bound tracking on bitwise operations) (v5.13-rc4) and backported to the stable kernels in v5.12.4,
    v5.11.21, and v5.10.37. The AND/OR issues were introduced by commit 3f50f132d840 (bpf: Verifier, do
    explicit ALU32 bounds tracking) (5.7-rc1) and the XOR variant was introduced by 2921c90d4718 (bpf:Fix a
    verifier failure with xor) ( 5.10-rc1). (CVE-2021-3490)

  - The io_uring subsystem in the Linux kernel allowed the MAX_RW_COUNT limit to be bypassed in the
    PROVIDE_BUFFERS operation, which led to negative values being usedin mem_rw when reading /proc/<PID>/mem.
    This could be used to create a heap overflow leading to arbitrary code execution in the kernel. It was
    addressed via commit d1f82808877b (io_uring: truncate lengths larger than MAX_RW_COUNT on provide
    buffers) (v5.13-rc1) and backported to the stable kernels in v5.12.4, v5.11.21, and v5.10.37. It was
    introduced in ddf0322db79c (io_uring: add IORING_OP_PROVIDE_BUFFERS) (v5.7-rc1). (CVE-2021-3491)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/notices/USN-4948-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected kernel package.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:N/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:H/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:H/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2021-3491");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");
  script_set_attribute(attribute:"exploit_framework_core", value:"true");
  script_set_attribute(attribute:"exploited_by_malware", value:"true");
  script_set_attribute(attribute:"metasploit_name", value:'Linux eBPF ALU32 32-bit Invalid Bounds Tracking LPE');
  script_set_attribute(attribute:"exploit_framework_metasploit", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2021/03/20");
  script_set_attribute(attribute:"patch_publication_date", value:"2021/05/11");
  script_set_attribute(attribute:"plugin_publication_date", value:"2021/05/12");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:20.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.10.0-1026-oem");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Ubuntu Local Security Checks");

  script_copyright(english:"Ubuntu Security Notice (C) 2021-2024 Canonical, Inc. / NASL script (C) 2021-2024 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl", "linux_alt_patch_detect.nasl");
  script_require_keys("Host/cpu", "Host/Ubuntu", "Host/Ubuntu/release", "Host/Debian/dpkg-l");

  exit(0);
}

include('debian_package.inc');
include('ksplice.inc');

if ( ! get_kb_item('Host/local_checks_enabled') ) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_release = get_kb_item('Host/Ubuntu/release');
if ( isnull(os_release) ) audit(AUDIT_OS_NOT, 'Ubuntu');
os_release = chomp(os_release);
if (! ('20.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 20.04', 'Ubuntu ' + os_release);
if ( ! get_kb_item('Host/Debian/dpkg-l') ) 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$" && 's390' >!< cpu && 'aarch64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Ubuntu', cpu);

var kernel_mappings = {
  '20.04': {
    '5.10.0': {
      'oem': '5.10.0-1026'
    }
  }
};

var host_kernel_release = get_kb_item('Host/uptrack-uname-r');
if (empty_or_null(host_kernel_release)) host_kernel_release = get_kb_item_or_exit('Host/uname-r');
var host_kernel_base_version = get_kb_item_or_exit('Host/Debian/kernel-base-version');
var host_kernel_type = get_kb_item_or_exit('Host/Debian/kernel-type');
if(empty_or_null(kernel_mappings[os_release][host_kernel_base_version][host_kernel_type])) audit(AUDIT_INST_VER_NOT_VULN, 'kernel ' + host_kernel_release);

var extra = '';
var kernel_fixed_version = kernel_mappings[os_release][host_kernel_base_version][host_kernel_type] + "-" + host_kernel_type;
if (deb_ver_cmp(ver1:host_kernel_release, ver2:kernel_fixed_version) < 0)
{
  extra = extra + 'Running Kernel level of ' + host_kernel_release + ' does not meet the minimum fixed level of ' + kernel_fixed_version + ' for this advisory.\n\n';
}
  else
{
  audit(AUDIT_PATCH_INSTALLED, 'Kernel package for USN-4948-1');
}

if (get_one_kb_item('Host/ksplice/kernel-cves'))
{
  var cve_list = make_list('CVE-2020-25670', 'CVE-2020-25671', 'CVE-2020-25672', 'CVE-2021-3483', 'CVE-2021-3489', 'CVE-2021-3490', 'CVE-2021-3491', 'CVE-2021-28688', 'CVE-2021-28951', 'CVE-2021-28952', 'CVE-2021-28964', 'CVE-2021-28971', 'CVE-2021-28972', 'CVE-2021-29264', 'CVE-2021-29266', 'CVE-2021-29646', 'CVE-2021-29647', 'CVE-2021-29649', 'CVE-2021-29650', 'CVE-2021-29657', 'CVE-2021-31916');
  if (ksplice_cves_check(cve_list))
  {
    audit(AUDIT_PATCH_INSTALLED, 'KSplice hotfix for USN-4948-1');
  }
  else
  {
    extra = extra + ksplice_reporting_text();
  }
}
if (extra) {
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    extra      : extra
  );
  exit(0);
}

References

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Confidence

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