A Linux kernel security update has been released for Ubuntu Linux 14.04 ESM, 16.04 LTS, and 18.04 LTS.

USN-5018-1: Linux kernel vulnerabilities

==========================================================================
Ubuntu Security Notice USN-5018-1
July 20, 2021

linux, linux-aws, linux-aws-hwe, linux-azure, linux-azure-4.15, linux-gcp,
linux-gcp-4.15, linux-hwe, linux-kvm, linux-oracle, linux-raspi2,
linux-snapdragon vulnerabilities
==========================================================================

A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 18.04 LTS
- Ubuntu 16.04 ESM
- Ubuntu 14.04 ESM

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- linux: Linux kernel
- linux-aws: Linux kernel for Amazon Web Services (AWS) systems
- linux-azure-4.15: Linux kernel for Microsoft Azure Cloud systems
- linux-gcp-4.15: Linux kernel for Google Cloud Platform (GCP) systems
- linux-kvm: Linux kernel for cloud environments
- linux-oracle: Linux kernel for Oracle Cloud systems
- linux-raspi2: Linux kernel for Raspberry Pi (V8) systems
- linux-snapdragon: Linux kernel for Qualcomm Snapdragon processors
- linux-aws-hwe: Linux kernel for Amazon Web Services (AWS-HWE) systems
- linux-azure: Linux kernel for Microsoft Azure Cloud systems
- linux-gcp: Linux kernel for Google Cloud Platform (GCP) systems
- linux-hwe: Linux hardware enablement (HWE) kernel

Details:

It was discovered that the virtual file system implementation in the Linux
kernel contained an unsigned to signed integer conversion error. A local
attacker could use this to cause a denial of service (system crash) or
execute arbitrary code. (CVE-2021-33909)

Piotr Krysiuk discovered that the eBPF implementation in the Linux kernel
did not properly enforce limits for pointer operations. A local attacker
could use this to cause a denial of service (system crash) or possibly
execute arbitrary code. (CVE-2021-33200)

Mathy Vanhoef discovered that the Linux kernel’s WiFi implementation did
not properly clear received fragments from memory in some situations. A
physically proximate attacker could possibly use this issue to inject
packets or expose sensitive information. (CVE-2020-24586)

Mathy Vanhoef discovered that the Linux kernel’s WiFi implementation
incorrectly handled encrypted fragments. A physically proximate attacker
could possibly use this issue to decrypt fragments. (CVE-2020-24587)

Mathy Vanhoef discovered that the Linux kernel’s WiFi implementation
incorrectly handled EAPOL frames from unauthenticated senders. A physically
proximate attacker could inject malicious packets to cause a denial of
service (system crash). (CVE-2020-26139)

Mathy Vanhoef discovered that the Linux kernel’s WiFi implementation could
reassemble mixed encrypted and plaintext fragments. A physically proximate
attacker could possibly use this issue to inject packets or exfiltrate
selected fragments. (CVE-2020-26147)

It was discovered that the bluetooth subsystem in the Linux kernel did not
properly perform access control. An authenticated attacker could possibly
use this to expose sensitive information. (CVE-2020-26558, CVE-2021-0129)

Or Cohen and Nadav Markus discovered a use-after-free vulnerability in the
nfc implementation in the Linux kernel. A privileged local attacker could
use this issue to cause a denial of service (system crash) or possibly
execute arbitrary code. (CVE-2021-23134)

Piotr Krysiuk discovered that the eBPF implementation in the Linux kernel
did not properly prevent speculative loads in certain situations. A local
attacker could use this to expose sensitive information (kernel memory).
(CVE-2021-31829)

It was discovered that a race condition in the kernel Bluetooth subsystem
could lead to use-after-free of slab objects. An attacker could use this
issue to possibly execute arbitrary code. (CVE-2021-32399)

It was discovered that a use-after-free existed in the Bluetooth HCI driver
of the Linux kernel. A local attacker could use this to cause a denial of
service (system crash) or possibly execute arbitrary code. (CVE-2021-33034)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 18.04 LTS:
linux-image-4.15.0-1078-oracle 4.15.0-1078.86
linux-image-4.15.0-1092-raspi2 4.15.0-1092.98
linux-image-4.15.0-1097-kvm 4.15.0-1097.99
linux-image-4.15.0-1106-gcp 4.15.0-1106.120
linux-image-4.15.0-1109-aws 4.15.0-1109.116
linux-image-4.15.0-1109-snapdragon 4.15.0-1109.118
linux-image-4.15.0-1121-azure 4.15.0-1121.134
linux-image-4.15.0-151-generic 4.15.0-151.157
linux-image-4.15.0-151-generic-lpae 4.15.0-151.157
linux-image-4.15.0-151-lowlatency 4.15.0-151.157
linux-image-aws-lts-18.04 4.15.0.1109.112
linux-image-azure-lts-18.04 4.15.0.1121.94
linux-image-gcp-lts-18.04 4.15.0.1106.125
linux-image-generic 4.15.0.151.139
linux-image-generic-lpae 4.15.0.151.139
linux-image-kvm 4.15.0.1097.93
linux-image-lowlatency 4.15.0.151.139
linux-image-oracle-lts-18.04 4.15.0.1078.88
linux-image-raspi2 4.15.0.1092.90
linux-image-snapdragon 4.15.0.1109.112
linux-image-virtual 4.15.0.151.139

Ubuntu 16.04 ESM:
linux-image-4.15.0-1078-oracle 4.15.0-1078.86~16.04.1
linux-image-4.15.0-1106-gcp 4.15.0-1106.120~16.04.1
linux-image-4.15.0-1109-aws 4.15.0-1109.116~16.04.1
linux-image-4.15.0-1121-azure 4.15.0-1121.134~16.04.1
linux-image-4.15.0-151-generic 4.15.0-151.157~16.04.1
linux-image-4.15.0-151-lowlatency 4.15.0-151.157~16.04.1
linux-image-aws-hwe 4.15.0.1109.100
linux-image-azure 4.15.0.1121.112
linux-image-gcp 4.15.0.1106.107
linux-image-generic-hwe-16.04 4.15.0.151.146
linux-image-gke 4.15.0.1106.107
linux-image-lowlatency-hwe-16.04 4.15.0.151.146
linux-image-oem 4.15.0.151.146
linux-image-oracle 4.15.0.1078.66
linux-image-virtual-hwe-16.04 4.15.0.151.146

Ubuntu 14.04 ESM:
linux-image-4.15.0-1121-azure 4.15.0-1121.134~14.04.1
linux-image-azure 4.15.0.1121.94

After a standard system update you need to reboot your computer to make
all the necessary changes.

ATTENTION: Due to an unavoidable ABI change the kernel updates have
been given a new version number, which requires you to recompile and
reinstall all third party kernel modules you might have installed.
Unless you manually uninstalled the standard kernel metapackages
(e.g. linux-generic, linux-generic-lts-RELEASE, linux-virtual,
linux-powerpc), a standard system upgrade will automatically perform
this as well.

References:
  https://ubuntu.com/security/notices/USN-5018-1
CVE-2020-24586, CVE-2020-24587, CVE-2020-26139, CVE-2020-26147,
CVE-2020-26558, CVE-2021-0129, CVE-2021-23134, CVE-2021-31829,
CVE-2021-32399, CVE-2021-33034, CVE-2021-33200, CVE-2021-33909

Package Information:
  https://launchpad.net/ubuntu/+source/linux/4.15.0-151.157
  https://launchpad.net/ubuntu/+source/linux-aws/4.15.0-1109.116
  https://launchpad.net/ubuntu/+source/linux-azure-4.15/4.15.0-1121.134
  https://launchpad.net/ubuntu/+source/linux-gcp-4.15/4.15.0-1106.120
  https://launchpad.net/ubuntu/+source/linux-kvm/4.15.0-1097.99
  https://launchpad.net/ubuntu/+source/linux-oracle/4.15.0-1078.86
  https://launchpad.net/ubuntu/+source/linux-raspi2/4.15.0-1092.98
  https://launchpad.net/ubuntu/+source/linux-snapdragon/4.15.0-1109.118