USN-4679-1: Linux kernel vulnerabilities

Releases

• Ubuntu 20.04 LTS
• Ubuntu 18.04 ESM

Packages

• linux - Linux kernel
• linux-aws - Linux kernel for Amazon Web Services (AWS) systems
• linux-aws-5.4 - Linux kernel for Amazon Web Services (AWS) systems
• linux-azure - Linux kernel for Microsoft Azure Cloud systems
• linux-azure-5.4 - Linux kernel for Microsoft Azure cloud systems
• linux-gcp - Linux kernel for Google Cloud Platform (GCP) systems
• linux-gcp-5.4 - Linux kernel for Google Cloud Platform (GCP) systems
• linux-gke-5.4 - Linux kernel for Google Container Engine (GKE) systems
• linux-hwe-5.4 - Linux hardware enablement (HWE) kernel
• linux-kvm - Linux kernel for cloud environments
• linux-oracle - Linux kernel for Oracle Cloud systems
• linux-oracle-5.4 - Linux kernel for Oracle Cloud systems
• linux-raspi - Linux kernel for Raspberry Pi (V8) systems
• linux-raspi-5.4 - 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)

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)

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)

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)

Update instructions

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

Ubuntu 20.04

• linux-image-5.4.0-1026-raspi - 5.4.0-1026.29
• linux-image-5.4.0-1031-kvm - 5.4.0-1031.32
• linux-image-5.4.0-1033-gcp - 5.4.0-1033.35
• linux-image-5.4.0-1034-aws - 5.4.0-1034.35
• linux-image-5.4.0-1034-oracle - 5.4.0-1034.36
• linux-image-5.4.0-1035-azure - 5.4.0-1035.36
• linux-image-5.4.0-59-generic - 5.4.0-59.65
• linux-image-5.4.0-59-generic-lpae - 5.4.0-59.65
• linux-image-5.4.0-59-lowlatency - 5.4.0-59.65
• linux-image-aws - 5.4.0.1034.35
• linux-image-azure - 5.4.0.1035.33
• linux-image-gcp - 5.4.0.1033.42
• linux-image-generic - 5.4.0.59.62
• linux-image-generic-lpae - 5.4.0.59.62
• linux-image-kvm - 5.4.0.1031.29
• linux-image-lowlatency - 5.4.0.59.62
• linux-image-oem - 5.4.0.59.62
• linux-image-oem-osp1 - 5.4.0.59.62
• linux-image-oracle - 5.4.0.1034.31
• linux-image-raspi - 5.4.0.1026.61
• linux-image-raspi2 - 5.4.0.1026.61
• linux-image-virtual - 5.4.0.59.62

Ubuntu 18.04

• linux-image-5.4.0-1026-raspi - 5.4.0-1026.29~18.04.1
• linux-image-5.4.0-1033-gcp - 5.4.0-1033.35~18.04.1
• linux-image-5.4.0-1033-gke - 5.4.0-1033.35~18.04.1
• linux-image-5.4.0-1034-aws - 5.4.0-1034.35~18.04.1
• linux-image-5.4.0-1034-oracle - 5.4.0-1034.36~18.04.1
• linux-image-5.4.0-1035-azure - 5.4.0-1035.36~18.04.1
• linux-image-5.4.0-59-generic - 5.4.0-59.65~18.04.1
• linux-image-5.4.0-59-generic-lpae - 5.4.0-59.65~18.04.1
• linux-image-5.4.0-59-lowlatency - 5.4.0-59.65~18.04.1
• linux-image-aws - 5.4.0.1034.19
• linux-image-azure - 5.4.0.1035.17
• linux-image-gcp - 5.4.0.1033.21
• linux-image-generic-hwe-18.04 - 5.4.0.59.65~18.04.54
• linux-image-generic-lpae-hwe-18.04 - 5.4.0.59.65~18.04.54
• linux-image-gke-5.4 - 5.4.0.1033.35~18.04.2
• linux-image-lowlatency-hwe-18.04 - 5.4.0.59.65~18.04.54
• linux-image-oem - 5.4.0.59.65~18.04.54
• linux-image-oem-osp1 - 5.4.0.59.65~18.04.54
• linux-image-oracle - 5.4.0.1034.36~18.04.18
• linux-image-raspi-hwe-18.04 - 5.4.0.1026.30
• linux-image-snapdragon-hwe-18.04 - 5.4.0.59.65~18.04.54
• linux-image-virtual-hwe-18.04 - 5.4.0.59.65~18.04.54

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

• CVE-2020-28974
• CVE-2020-25656
• CVE-2020-25704
• CVE-2020-27675
• CVE-2020-27777
• CVE-2020-25668

Related notices

• USN-4680-1: linux-image-4.15.0-1082-kvm, linux-image-snapdragon, linux-kvm, linux-image-raspi2, linux-image-lowlatency-hwe-16.04, linux-image-generic-lpae-hwe-16.04, linux-aws-hwe, linux-gcp-4.15, linux-image-lowlatency-hwe-16.04-edge, linux-image-4.15.0-129-generic-lpae, linux-image-oem, linux-image-4.15.0-129-generic, linux-image-4.15.0-1094-snapdragon, linux-oracle, linux-raspi2, linux-image-generic, linux-image-virtual-hwe-16.04-edge, linux-image-4.15.0-1103-azure, linux-image-4.15.0-1077-gke, linux-image-azure-lts-18.04, linux-image-4.15.0-1077-raspi2, linux-image-gcp-lts-18.04, linux-image-lowlatency, linux-image-aws-lts-18.04, linux-image-gcp, linux-image-gke-4.15, linux-hwe, linux-image-generic-hwe-16.04, linux-image-generic-hwe-16.04-edge, linux-image-azure-edge, linux-image-generic-lpae-hwe-16.04-edge, linux-image-aws-hwe, linux-image-oracle-lts-18.04, linux-image-gke, linux-azure-4.15, linux-image-4.15.0-129-lowlatency, linux-image-4.15.0-1062-oracle, linux-image-generic-lpae, linux-gcp, linux-image-4.15.0-1091-aws, linux-image-azure, linux-aws, linux-image-oracle, linux-image-4.15.0-1091-gcp, linux, linux-azure, linux-image-virtual-hwe-16.04, linux-snapdragon, linux-image-virtual, linux-image-kvm, linux-gke-4.15
• USN-4681-1: linux-image-aws, linux-image-virtual-lts-wily, linux-image-4.4.0-198-powerpc-smp, linux-image-4.4.0-198-generic-lpae, linux-image-snapdragon, linux-kvm, linux-image-4.4.0-1083-aws, linux-image-raspi2, linux-image-4.4.0-1143-raspi2, linux-image-powerpc64-smp, linux-image-powerpc64-emb-lts-wily, linux-image-powerpc-smp-lts-utopic, linux-image-powerpc-e500mc-lts-vivid, linux-raspi2, linux-image-generic-lpae-lts-vivid, linux-image-generic, linux-image-powerpc64-emb, linux-image-generic-lpae-lts-utopic, linux-image-4.4.0-198-powerpc64-emb, linux-image-powerpc64-smp-lts-wily, linux-image-generic-lpae-lts-xenial, linux-image-powerpc64-smp-lts-xenial, linux-image-lowlatency-lts-vivid, linux-image-4.4.0-198-powerpc-e500mc, linux-image-powerpc-smp-lts-vivid, linux-image-lowlatency, linux-image-4.4.0-1085-kvm, linux-image-4.4.0-198-powerpc64-smp, linux-image-lowlatency-lts-xenial, linux-image-powerpc-e500mc, linux-image-4.4.0-1147-snapdragon, linux-image-4.4.0-198-generic, linux-image-powerpc64-smp-lts-utopic, linux-image-powerpc64-smp-lts-vivid, linux-image-virtual-lts-utopic, linux-image-virtual-lts-xenial, linux-image-virtual-lts-vivid, linux-image-powerpc-smp, linux-image-powerpc64-emb-lts-vivid, linux-image-lowlatency-lts-wily, linux-image-generic-lts-vivid, linux-image-powerpc-smp-lts-wily, linux-image-powerpc-smp-lts-xenial, linux-image-generic-lts-wily, linux-image-powerpc-e500mc-lts-utopic, linux-image-generic-lpae, linux-image-lowlatency-lts-utopic, linux-lts-xenial, linux-image-powerpc-e500mc-lts-xenial, linux-image-generic-lts-xenial, linux-image-generic-lpae-lts-wily, linux-aws, linux-image-generic-lts-utopic, linux-image-powerpc-e500mc-lts-wily, linux-image-powerpc64-emb-lts-utopic, linux, linux-image-4.4.0-198-lowlatency, linux-image-4.4.0-1119-aws, linux-image-powerpc64-emb-lts-xenial, linux-snapdragon, linux-image-virtual, linux-image-kvm
• USN-4683-1: linux-oem-5.6, linux-image-oem-20.04, linux-image-5.6.0-1039-oem
• USN-4751-1: linux-image-5.8.0-44-generic-64k, linux-image-aws, linux-image-generic-64k-hwe-20.04, linux-image-generic-hwe-20.04-edge, linux-kvm, linux-image-lowlatency-hwe-20.04, linux-image-5.8.0-1023-gcp, linux-image-generic-lpae-hwe-20.04-edge, linux-image-5.8.0-1021-oracle, linux-image-5.8.0-1016-raspi, linux-image-virtual-hwe-20.04-edge, linux-image-raspi-nolpae, linux-image-lowlatency-hwe-20.04-edge, linux-image-5.8.0-44-lowlatency, linux-hwe-5.8, linux-image-5.8.0-44-generic-lpae, linux-oracle, linux-image-generic, linux-image-generic-lpae-hwe-20.04, linux-image-raspi, linux-image-lowlatency, linux-image-5.8.0-1016-raspi-nolpae, linux-image-5.8.0-1023-azure, linux-image-gcp, linux-raspi, linux-image-virtual-hwe-20.04, linux-image-generic-64k-hwe-20.04-edge, linux-image-oem-20.04, linux-image-gke, linux-image-generic-hwe-20.04, linux-image-generic-lpae, linux-gcp, linux-image-5.8.0-44-generic, linux-image-azure, linux-aws, linux-image-oracle, linux-image-5.8.0-1024-aws, linux, linux-azure, linux-image-generic-64k, linux-image-5.8.0-1019-kvm, linux-image-virtual, linux-image-kvm
• USN-4710-1: linux-image-lowlatency-hwe-16.04, linux-image-generic-lpae-hwe-16.04, linux-image-lowlatency-hwe-16.04-edge, linux-image-4.15.0-133-lowlatency, linux-image-oem, linux-image-generic, linux-image-virtual-hwe-16.04-edge, linux-image-4.15.0-133-generic, linux-image-4.15.0-135-generic-lpae, linux-image-lowlatency, linux-hwe, linux-image-generic-hwe-16.04, linux-image-generic-hwe-16.04-edge, linux-image-generic-lpae-hwe-16.04-edge, linux-image-4.15.0-133-generic-lpae, linux-image-4.15.0-135-generic, linux-image-generic-lpae, linux-image-4.15.0-135-lowlatency, linux, linux-image-virtual-hwe-16.04, linux-image-virtual
• USN-4711-1: linux-image-snapdragon, linux-kvm, linux-image-raspi2, linux-image-kvm, linux-image-4.15.0-1078-raspi2, linux-aws-hwe, linux-gcp-4.15, linux-image-4.15.0-1095-snapdragon, linux-raspi2, linux-image-4.15.0-1106-azure, linux-oracle, linux-image-4.15.0-1084-kvm, linux-image-azure-lts-18.04, linux-image-gcp-lts-18.04, linux-image-aws-lts-18.04, linux-image-gcp, linux-image-gke-4.15, linux-image-azure-edge, linux-image-aws-hwe, linux-image-4.15.0-1093-aws, linux-image-gke, linux-azure-4.15, linux-image-oracle-lts-18.04, linux-gcp, linux-image-azure, linux-aws, linux-image-oracle, linux-azure, linux-image-4.15.0-1092-gcp, linux-snapdragon, linux-image-4.15.0-1064-oracle, linux-image-4.15.0-1078-gke, linux-gke-4.15
• USN-4752-1: linux-oem-5.6, linux-image-5.6.0-1048-oem, linux-image-oem-20.04
• USN-4708-1: linux-image-virtual-lts-wily, linux-image-4.4.0-201-powerpc64-emb, linux-image-4.4.0-201-powerpc-e500mc, linux-image-powerpc64-smp, linux-image-powerpc64-emb-lts-wily, linux-image-4.4.0-201-generic-lpae, linux-image-powerpc-smp-lts-utopic, linux-image-powerpc-e500mc-lts-vivid, linux-image-4.4.0-201-lowlatency, linux-image-generic-lpae-lts-vivid, linux-image-generic, linux-image-powerpc64-emb, linux-image-generic-lpae-lts-utopic, linux-image-powerpc64-smp-lts-wily, linux-image-generic-lpae-lts-xenial, linux-image-powerpc64-smp-lts-xenial, linux-image-4.4.0-201-generic, linux-image-lowlatency-lts-vivid, linux-image-powerpc-smp-lts-vivid, linux-image-lowlatency, linux-image-powerpc-e500mc, linux-image-powerpc64-smp-lts-utopic, linux-image-lowlatency-lts-xenial, linux-image-powerpc64-smp-lts-vivid, linux-image-virtual-lts-utopic, linux-image-virtual-lts-xenial, linux-image-virtual-lts-vivid, linux-image-powerpc-smp, linux-image-4.4.0-201-powerpc-smp, linux-image-powerpc64-emb-lts-vivid, linux-image-lowlatency-lts-wily, linux-image-generic-lts-vivid, linux-image-powerpc-smp-lts-wily, linux-image-4.4.0-201-powerpc64-smp, linux-image-powerpc-smp-lts-xenial, linux-image-generic-lts-wily, linux-image-powerpc-e500mc-lts-utopic, linux-image-generic-lpae, linux-image-lowlatency-lts-utopic, linux-lts-xenial, linux-image-powerpc-e500mc-lts-xenial, linux-image-generic-lts-xenial, linux-image-generic-lpae-lts-wily, linux-image-powerpc64-emb-lts-utopic, linux-image-generic-lts-utopic, linux-image-powerpc-e500mc-lts-wily, linux-image-powerpc64-emb-lts-xenial, linux, linux-image-virtual