USN-4751-1: Linux kernel vulnerabilities

25 February 2021

Several security issues were fixed in the Linux kernel.

Releases

Packages

  • linux - Linux kernel
  • linux-aws - Linux kernel for Amazon Web Services (AWS) systems
  • linux-azure - Linux kernel for Microsoft Azure Cloud systems
  • linux-gcp - Linux kernel for Google Cloud Platform (GCP) systems
  • linux-hwe-5.8 - Linux hardware enablement (HWE) kernel
  • linux-kvm - Linux kernel for cloud environments
  • linux-oracle - Linux kernel for Oracle Cloud systems
  • linux-raspi - Linux kernel for Raspberry Pi (V8) systems

Details

It was discovered that the console keyboard driver in the Linux kernel
contained a race condition. A local attacker could use this to expose
sensitive information (kernel memory). (CVE-2020-25656)

Minh Yuan discovered that the tty driver in the Linux kernel contained race
conditions when handling fonts. A local attacker could possibly use this to
expose sensitive information (kernel memory). (CVE-2020-25668)

Bodong Zhao discovered a use-after-free in the Sun keyboard driver
implementation in the Linux kernel. A local attacker could use this to
cause a denial of service or possibly execute arbitrary code.
(CVE-2020-25669)

Kiyin (尹亮) discovered that the perf subsystem in the Linux kernel did
not properly deallocate memory in some situations. A privileged attacker
could use this to cause a denial of service (kernel memory exhaustion).
(CVE-2020-25704)

Julien Grall discovered that the Xen dom0 event handler in the Linux kernel
did not properly limit the number of events queued. An attacker in a guest
VM could use this to cause a denial of service in the host OS.
(CVE-2020-27673)

Jinoh Kang discovered that the Xen event channel infrastructure in the
Linux kernel contained a race condition. An attacker in guest could
possibly use this to cause a denial of service (dom0 crash).
(CVE-2020-27675)

Daniel Axtens discovered that PowerPC RTAS implementation in the Linux
kernel did not properly restrict memory accesses in some situations. A
privileged local attacker could use this to arbitrarily modify kernel
memory, potentially bypassing kernel lockdown restrictions.
(CVE-2020-27777)

It was discovered that the jfs file system implementation in the Linux
kernel contained an out-of-bounds read vulnerability. A local attacker
could use this to possibly cause a denial of service (system crash).
(CVE-2020-27815)

Shisong Qin and Bodong Zhao discovered that Speakup screen reader driver in
the Linux kernel did not correctly handle setting line discipline in some
situations. A local attacker could use this to cause a denial of service
(system crash). (CVE-2020-27830, CVE-2020-28941)

It was discovered that a use-after-free vulnerability existed in the
infiniband hfi1 device driver in the Linux kernel. A local attacker could
possibly use this to cause a denial of service (system crash).
(CVE-2020-27835)

It was discovered that an information leak existed in the syscall
implementation in the Linux kernel on 32 bit systems. A local attacker
could use this to expose sensitive information (kernel memory).
(CVE-2020-28588)

Minh Yuan discovered that the framebuffer console driver in the Linux
kernel did not properly handle fonts in some conditions. A local attacker
could use this to cause a denial of service (system crash) or possibly
expose sensitive information (kernel memory). (CVE-2020-28974)

Michael Kurth and Pawel Wieczorkiewicz discovered that the Xen event
processing backend in the Linux kernel did not properly limit the number of
events queued. An attacker in a guest VM could use this to cause a denial
of service in the host OS. (CVE-2020-29568)

Olivier Benjamin and Pawel Wieczorkiewicz discovered a race condition the
Xen paravirt block backend in the Linux kernel, leading to a use-after-free
vulnerability. An attacker in a guest VM could use this to cause a denial
of service in the host OS. (CVE-2020-29569)

Jann Horn discovered that the tty subsystem of the Linux kernel did not use
consistent locking in some situations, leading to a read-after-free
vulnerability. A local attacker could use this to cause a denial of service
(system crash) or possibly expose sensitive information (kernel memory).
(CVE-2020-29660)

Jann Horn discovered a race condition in the tty subsystem of the Linux
kernel in the locking for the TIOCSPGRP ioctl(), leading to a use-after-
free vulnerability. A local attacker could use this to cause a denial of
service (system crash) or possibly execute arbitrary code. (CVE-2020-29661)

It was discovered that a race condition existed that caused the Linux
kernel to not properly restrict exit signal delivery. A local attacker
could possibly use this to send signals to arbitrary processes.
(CVE-2020-35508)

Update instructions

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

Ubuntu 20.10
Ubuntu 20.04

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.

Related notices

  • USN-4912-1: linux-image-5.6.0-1053-oem, linux-image-oem-20.04, linux-oem-5.6
  • USN-4680-1: linux-image-powerpc-smp, linux-image-generic-hwe-16.04, linux-image-generic-lpae-hwe-16.04, linux-image-lowlatency, linux-image-azure, linux-image-gcp, linux-image-powerpc64-smp, linux-kvm, linux-azure, linux-image-generic, linux-image-4.15.0-1091-aws, linux-image-aws-lts-18.04, linux-image-powerpc-e500mc, linux-image-4.15.0-129-generic, linux-image-generic-hwe-16.04-edge, linux-snapdragon, linux-image-4.15.0-1077-gke, linux-image-azure-edge, linux-image-virtual-hwe-16.04-edge, linux-image-lowlatency-hwe-16.04, linux-image-oem, linux-image-gke, linux-image-raspi2, linux-image-azure-lts-18.04, linux-image-generic-lpae-hwe-16.04-edge, linux-image-generic-lpae, linux-azure-4.15, linux-image-kvm, linux-image-oracle, linux-image-gcp-lts-18.04, linux-hwe, linux-image-gke-4.15, linux-image-4.15.0-129-generic-lpae, linux-aws-hwe, linux-raspi2, linux-gcp, linux-image-4.15.0-1103-azure, linux-oracle, linux-image-4.15.0-1091-gcp, linux-image-virtual-hwe-16.04, linux-image-4.15.0-1094-snapdragon, linux-gcp-4.15, linux-image-4.15.0-1077-raspi2, linux-image-aws-hwe, linux-image-virtual, linux-gke-4.15, linux-aws, linux-image-4.15.0-1082-kvm, linux-image-powerpc64-emb, linux-image-snapdragon, linux-image-4.15.0-1062-oracle, linux, linux-image-4.15.0-129-lowlatency, linux-image-lowlatency-hwe-16.04-edge, linux-image-oracle-lts-18.04
  • USN-4679-1: linux-image-lowlatency, linux-oracle-5.4, linux-image-snapdragon-hwe-18.04, linux-image-lowlatency-hwe-18.04-edge, linux-image-azure, linux-image-gcp, linux-kvm, linux-image-virtual-hwe-20.04, linux-azure, linux-image-generic, linux-image-generic-hwe-18.04, linux-image-generic-lpae-hwe-18.04, linux-image-raspi2-hwe-18.04-edge, linux-azure-5.4, linux-image-5.4.0-59-generic, linux-image-azure-edge, linux-image-gcp-edge, linux-image-oracle-edge, linux-image-raspi, linux-image-raspi-hwe-18.04-edge, linux-image-5.4.0-1026-raspi, linux-image-aws-edge, linux-image-oem, linux-image-generic-hwe-18.04-edge, linux-image-raspi2, linux-image-aws, linux-image-generic-hwe-20.04, linux-image-generic-lpae-hwe-20.04, linux-image-lowlatency-hwe-20.04, linux-aws-5.4, linux-hwe-5.4, linux-image-generic-lpae, linux-image-kvm, linux-image-oem-osp1, linux-image-oracle, linux-image-virtual-hwe-18.04, linux-image-raspi-hwe-18.04, linux-image-5.4.0-59-lowlatency, linux-gcp-5.4, linux-image-5.4.0-1033-gke, linux-image-5.4.0-1033-gcp, linux-image-5.4.0-1034-aws, linux-gcp, linux-raspi-5.4, linux-image-raspi2-hwe-18.04, linux-image-5.4.0-1034-oracle, linux-oracle, linux-image-5.4.0-1031-kvm, linux-image-generic-lpae-hwe-18.04-edge, linux-image-virtual-hwe-18.04-edge, linux-image-5.4.0-59-generic-lpae, linux-raspi, linux-image-5.4.0-1035-azure, linux-image-virtual, linux-aws, linux-image-lowlatency-hwe-18.04, linux-gke-5.4, linux-image-snapdragon-hwe-18.04-edge, linux, linux-image-gke-5.4
  • USN-4752-1: linux-image-oem-20.04, linux-image-5.6.0-1048-oem, linux-oem-5.6
  • USN-4683-1: linux-image-5.6.0-1039-oem, linux-image-oem-20.04, linux-oem-5.6
  • USN-4708-1: linux-image-powerpc-smp, linux-image-generic-lts-wily, linux-image-lowlatency, linux-lts-xenial, linux-image-generic-lpae-lts-vivid, linux-image-powerpc64-smp, linux-image-4.4.0-201-generic, linux-image-powerpc-smp-lts-xenial, linux-image-powerpc-e500mc-lts-vivid, linux-image-4.4.0-201-powerpc64-smp, linux-image-generic, linux-image-virtual-lts-xenial, linux-image-powerpc64-smp-lts-vivid, linux-image-powerpc-e500mc, linux-image-generic-lts-xenial, linux-image-4.4.0-201-powerpc-e500mc, linux-image-generic-lts-utopic, linux-image-4.4.0-201-powerpc64-emb, linux-image-powerpc-e500mc-lts-xenial, linux-image-powerpc64-emb-lts-vivid, linux-image-4.4.0-201-lowlatency, linux-image-generic-lpae-lts-wily, linux-image-powerpc64-smp-lts-xenial, linux-image-generic-lpae-lts-utopic, linux-image-4.4.0-201-powerpc-smp, linux-image-powerpc-smp-lts-wily, linux-image-powerpc64-emb-lts-xenial, linux-image-lowlatency-lts-xenial, linux-image-powerpc64-emb-lts-utopic, linux-image-powerpc64-emb-lts-wily, linux-image-powerpc-smp-lts-utopic, linux-image-generic-lpae, linux-image-generic-lpae-lts-xenial, linux-image-lowlatency-lts-wily, linux-image-lowlatency-lts-vivid, linux-image-virtual-lts-utopic, linux-image-lowlatency-lts-utopic, linux-image-powerpc-e500mc-lts-wily, linux-image-powerpc64-smp-lts-utopic, linux-image-virtual-lts-wily, linux-image-4.4.0-201-generic-lpae, linux-image-powerpc-e500mc-lts-utopic, linux-image-powerpc-smp-lts-vivid, linux-image-virtual-lts-vivid, linux-image-powerpc64-smp-lts-wily, linux-image-generic-lts-vivid, linux-image-virtual, linux-image-powerpc64-emb, linux
  • USN-4710-1: linux-image-powerpc-smp, linux-image-generic-hwe-16.04, linux-image-generic-lpae-hwe-16.04, linux-image-lowlatency, linux-image-4.15.0-135-generic, linux-image-powerpc64-smp, linux-image-generic, linux-image-powerpc-e500mc, linux-image-generic-hwe-16.04-edge, linux-image-virtual-hwe-16.04-edge, linux-image-lowlatency-hwe-16.04, linux-image-oem, linux-image-4.15.0-135-generic-lpae, linux-image-4.15.0-135-lowlatency, linux-image-4.15.0-133-lowlatency, linux-image-generic-lpae-hwe-16.04-edge, linux-image-generic-lpae, linux-hwe, linux-image-4.15.0-133-generic-lpae, linux-image-4.15.0-133-generic, linux-image-virtual-hwe-16.04, linux-image-virtual, linux-image-powerpc64-emb, linux, linux-image-lowlatency-hwe-16.04-edge
  • USN-4876-1: linux-image-powerpc-smp, linux-image-generic-lts-wily, linux-image-lowlatency, linux-image-4.4.0-204-powerpc-smp, linux-lts-xenial, linux-image-generic-lpae-lts-vivid, linux-image-powerpc64-smp, linux-image-4.4.0-204-lowlatency, linux-image-powerpc-smp-lts-xenial, linux-image-powerpc-e500mc-lts-vivid, linux-image-generic, linux-image-virtual-lts-xenial, linux-kvm, linux-image-powerpc64-smp-lts-vivid, linux-image-powerpc-e500mc, linux-image-generic-lts-xenial, linux-image-4.4.0-1147-raspi2, linux-snapdragon, linux-image-generic-lts-utopic, linux-image-powerpc-e500mc-lts-xenial, linux-image-powerpc64-emb-lts-vivid, linux-image-generic-lpae-lts-wily, linux-image-powerpc64-smp-lts-xenial, linux-image-4.4.0-1151-snapdragon, linux-image-4.4.0-204-generic, linux-image-generic-lpae-lts-utopic, linux-image-4.4.0-1123-aws, linux-image-4.4.0-204-powerpc-e500mc, linux-image-raspi2, linux-image-powerpc-smp-lts-wily, linux-image-aws, linux-image-powerpc64-emb-lts-xenial, linux-image-lowlatency-lts-xenial, linux-image-4.4.0-1089-kvm, linux-image-powerpc64-emb-lts-utopic, linux-image-powerpc64-emb-lts-wily, linux-image-powerpc-smp-lts-utopic, linux-image-generic-lpae, linux-image-generic-lpae-lts-xenial, linux-image-kvm, linux-image-lowlatency-lts-wily, linux-image-lowlatency-lts-vivid, linux-image-virtual-lts-utopic, linux-image-lowlatency-lts-utopic, linux-image-powerpc-e500mc-lts-wily, linux-image-powerpc64-smp-lts-utopic, linux-image-virtual-lts-wily, linux-image-4.4.0-204-powerpc64-emb, linux-raspi2, linux-image-4.4.0-204-powerpc64-smp, linux-image-powerpc-e500mc-lts-utopic, linux-image-powerpc-smp-lts-vivid, linux-image-virtual-lts-vivid, linux-image-powerpc64-smp-lts-wily, linux-image-generic-lts-vivid, linux-image-virtual, linux-image-4.4.0-204-generic-lpae, linux-image-4.4.0-1087-aws, linux-aws, linux-image-powerpc64-emb, linux-image-snapdragon, linux
  • USN-4748-1: linux-image-4.4.0-203-generic-lpae, linux-image-powerpc-smp, linux-image-generic-lts-wily, linux-image-lowlatency, linux-lts-xenial, linux-image-4.4.0-203-powerpc64-emb, linux-image-generic-lpae-lts-vivid, linux-image-powerpc64-smp, linux-kvm, linux-image-powerpc-smp-lts-xenial, linux-image-powerpc-e500mc-lts-vivid, linux-image-generic, linux-image-virtual-lts-xenial, linux-image-powerpc64-smp-lts-vivid, linux-image-powerpc-e500mc, linux-image-generic-lts-xenial, linux-image-4.4.0-203-powerpc-smp, linux-image-4.4.0-1150-snapdragon, linux-snapdragon, linux-image-generic-lts-utopic, linux-image-powerpc-e500mc-lts-xenial, linux-image-4.4.0-203-generic, linux-image-4.4.0-1122-aws, linux-image-generic-lpae-lts-wily, linux-image-powerpc64-emb-lts-vivid, linux-image-4.4.0-203-lowlatency, linux-image-powerpc64-smp-lts-xenial, linux-image-4.4.0-1146-raspi2, linux-image-generic-lpae-lts-utopic, linux-image-4.4.0-1086-aws, linux-image-raspi2, linux-image-powerpc-smp-lts-wily, linux-image-aws, linux-image-powerpc64-emb-lts-xenial, linux-image-4.4.0-203-powerpc64-smp, linux-image-lowlatency-lts-xenial, linux-image-powerpc64-emb-lts-utopic, linux-image-powerpc64-emb-lts-wily, linux-image-powerpc-smp-lts-utopic, linux-image-generic-lpae, linux-image-generic-lpae-lts-xenial, linux-image-kvm, linux-image-lowlatency-lts-wily, linux-image-lowlatency-lts-vivid, linux-image-virtual-lts-utopic, linux-image-lowlatency-lts-utopic, linux-image-powerpc-e500mc-lts-wily, linux-image-powerpc64-smp-lts-utopic, linux-image-virtual-lts-wily, linux-raspi2, linux-image-4.4.0-1088-kvm, linux-image-4.4.0-203-powerpc-e500mc, linux-image-powerpc-e500mc-lts-utopic, linux-image-powerpc-smp-lts-vivid, linux-image-virtual-lts-vivid, linux-image-powerpc64-smp-lts-wily, linux-image-generic-lts-vivid, linux-image-virtual, linux-aws, linux-image-powerpc64-emb, linux-image-snapdragon, linux
  • USN-4681-1: linux-image-4.4.0-198-lowlatency, linux-image-4.4.0-198-powerpc-e500mc, linux-image-generic-lts-wily, linux-image-lowlatency, linux-image-powerpc-smp, linux-lts-xenial, linux-image-4.4.0-198-generic, linux-image-generic-lpae-lts-vivid, linux-image-powerpc64-smp, linux-kvm, linux-image-powerpc-smp-lts-xenial, linux-image-powerpc-e500mc-lts-vivid, linux-image-generic, linux-image-virtual-lts-xenial, linux-image-powerpc64-smp-lts-vivid, linux-image-powerpc-e500mc, linux-image-generic-lts-xenial, linux-snapdragon, linux-image-4.4.0-198-powerpc64-emb, linux-image-4.4.0-1083-aws, linux-image-generic-lts-utopic, linux-image-powerpc-e500mc-lts-xenial, linux-image-powerpc64-emb-lts-vivid, linux-image-generic-lpae-lts-wily, linux-image-powerpc64-smp-lts-xenial, linux-image-generic-lpae-lts-utopic, linux-image-4.4.0-1147-snapdragon, linux-image-raspi2, linux-image-powerpc-smp-lts-wily, linux-image-aws, linux-image-powerpc64-emb-lts-xenial, linux-image-lowlatency-lts-xenial, linux-image-powerpc64-emb-lts-utopic, linux-image-powerpc64-emb-lts-wily, linux-image-powerpc-smp-lts-utopic, linux-image-generic-lpae, linux-image-generic-lpae-lts-xenial, linux-image-kvm, linux-image-lowlatency-lts-wily, linux-image-4.4.0-198-powerpc-smp, linux-image-lowlatency-lts-vivid, linux-image-lowlatency-lts-utopic, linux-image-powerpc-e500mc-lts-wily, linux-image-powerpc64-smp-lts-utopic, linux-image-virtual-lts-utopic, linux-image-virtual-lts-wily, linux-raspi2, linux-image-powerpc-e500mc-lts-utopic, linux-image-powerpc-smp-lts-vivid, linux-image-virtual-lts-vivid, linux-image-powerpc64-smp-lts-wily, linux-image-4.4.0-198-generic-lpae, linux-image-generic-lts-vivid, linux-image-virtual, linux-aws, linux-image-4.4.0-1085-kvm, linux-image-4.4.0-198-powerpc64-smp, linux-image-powerpc64-emb, linux-image-snapdragon, linux, linux-image-4.4.0-1119-aws, linux-image-4.4.0-1143-raspi2
  • USN-4750-1: linux-image-5.4.0-1036-gke, linux-image-lowlatency, linux-oracle-5.4, linux-image-snapdragon-hwe-18.04, linux-image-lowlatency-hwe-18.04-edge, linux-image-azure, linux-image-gcp, linux-kvm, linux-azure, linux-image-generic, linux-image-5.4.0-1040-azure, linux-image-5.4.0-66-generic, linux-image-generic-hwe-18.04, linux-image-generic-lpae-hwe-18.04, linux-image-raspi2-hwe-18.04-edge, linux-azure-5.4, linux-image-azure-edge, linux-image-gcp-edge, linux-image-5.4.0-1038-aws, linux-image-oracle-edge, linux-image-raspi, linux-image-raspi-hwe-18.04-edge, linux-image-5.4.0-1037-gcp, linux-image-aws-edge, linux-image-oem, linux-image-generic-hwe-18.04-edge, linux-image-raspi2, linux-gkeop, linux-image-aws, linux-image-5.4.0-1029-raspi, linux-aws-5.4, linux-hwe-5.4, linux-image-generic-lpae, linux-image-kvm, linux-image-oem-osp1, linux-image-oracle, linux-image-5.4.0-1038-oracle, linux-image-virtual-hwe-18.04, linux-image-raspi-hwe-18.04, linux-gcp-5.4, linux-raspi-5.4, linux-gcp, linux-gkeop-5.4, linux-image-raspi2-hwe-18.04, linux-oracle, linux-image-generic-lpae-hwe-18.04-edge, linux-image-virtual-hwe-18.04-edge, linux-raspi, linux-image-gkeop, linux-image-5.4.0-66-generic-lpae, linux-image-virtual, linux-image-5.4.0-1033-kvm, linux-aws, linux-image-5.4.0-1010-gkeop, linux-image-lowlatency-hwe-18.04, linux-gke-5.4, linux-image-gkeop-5.4, linux-image-snapdragon-hwe-18.04-edge, linux, linux-image-5.4.0-66-lowlatency, linux-image-gke-5.4
  • USN-4709-1: linux-image-4.4.0-1149-snapdragon, linux-image-kvm, linux-image-4.4.0-1087-kvm, linux-image-4.4.0-1085-aws, linux-aws, linux-image-4.4.0-1121-aws, linux-image-snapdragon, linux-kvm, linux-raspi2, linux-image-raspi2, linux-image-aws, linux-image-4.4.0-1145-raspi2, linux-snapdragon
  • USN-4749-1: linux-image-4.15.0-136-generic, linux-image-powerpc-smp, linux-image-generic-hwe-16.04, linux-image-generic-lpae-hwe-16.04, linux-image-lowlatency, linux-image-azure, linux-image-gcp, linux-image-4.15.0-136-generic-lpae, linux-image-powerpc64-smp, linux-image-4.15.0-1108-azure, linux-kvm, linux-image-4.15.0-1065-oracle, linux-azure, linux-image-4.15.0-1085-kvm, linux-image-generic, linux-image-aws-lts-18.04, linux-image-powerpc-e500mc, linux-image-dell300x, linux-image-generic-hwe-16.04-edge, linux-snapdragon, linux-image-4.15.0-1096-snapdragon, linux-image-azure-edge, linux-image-virtual-hwe-16.04-edge, linux-image-4.15.0-136-lowlatency, linux-image-lowlatency-hwe-16.04, linux-image-oem, linux-image-gke, linux-image-raspi2, linux-image-azure-lts-18.04, linux-image-generic-lpae-hwe-16.04-edge, linux-image-generic-lpae, linux-azure-4.15, linux-image-kvm, linux-image-4.15.0-1079-raspi2, linux-image-oracle, linux-image-4.15.0-1079-gke, linux-image-gcp-lts-18.04, linux-hwe, linux-image-gke-4.15, linux-aws-hwe, linux-dell300x, linux-raspi2, linux-gcp, linux-oracle, linux-image-4.15.0-1094-aws, linux-image-virtual-hwe-16.04, linux-image-virtual, linux-gcp-4.15, linux-image-4.15.0-1012-dell300x, linux-image-aws-hwe, linux-gke-4.15, linux-aws, linux-image-4.15.0-1093-gcp, linux-image-powerpc64-emb, linux-image-snapdragon, linux, linux-image-lowlatency-hwe-16.04-edge, linux-image-oracle-lts-18.04
  • USN-4711-1: linux-image-4.15.0-1106-azure, linux-image-azure, linux-image-gcp, linux-image-4.15.0-1064-oracle, linux-kvm, linux-azure, linux-image-4.15.0-1093-aws, linux-image-4.15.0-1095-snapdragon, linux-image-aws-lts-18.04, linux-snapdragon, linux-image-azure-edge, linux-image-gke, linux-image-raspi2, linux-image-4.15.0-1078-raspi2, linux-image-azure-lts-18.04, linux-image-4.15.0-1078-gke, linux-azure-4.15, linux-image-kvm, linux-image-oracle, linux-image-gcp-lts-18.04, linux-image-gke-4.15, linux-aws-hwe, linux-image-4.15.0-1084-kvm, linux-raspi2, linux-gcp, linux-oracle, linux-gcp-4.15, linux-image-aws-hwe, linux-gke-4.15, linux-aws, linux-image-4.15.0-1092-gcp, linux-image-snapdragon, linux-image-oracle-lts-18.04