USN-4915-1: Linux kernel (OEM) vulnerabilities

Releases

• Ubuntu 20.04 LTS

Packages

• linux-oem-5.6 - Linux kernel for OEM systems

Details

It was discovered that the overlayfs implementation in the Linux kernel did
not properly validate the application of file system capabilities with
respect to user namespaces. A local attacker could use this to gain
elevated privileges. (CVE-2021-3493)

Vincent Dehors discovered that the shiftfs file system in the Ubuntu Linux
kernel did not properly handle faults in copy_from_user() when passing
through ioctls to an underlying file system. A local attacker could use
this to cause a denial of service (memory exhaustion) or execute arbitrary
code. (CVE-2021-3492)

Update instructions

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

Ubuntu 20.04

• linux-image-5.6.0-1054-oem - 5.6.0-1054.58
• linux-image-oem-20.04 - 5.6.0.1054.50

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-2021-3493
• CVE-2021-3492

Related notices

• USN-4916-1: linux-dell300x, linux-image-powerpc-smp-lts-utopic, linux-kvm, linux-aws-hwe, linux-image-lowlatency-hwe-16.04-edge, linux-image-virtual-lts-vivid, linux-image-powerpc64-emb-lts-vivid, linux-image-virtual-lts-wily, linux-image-generic-lts-wily, linux-image-azure-lts-18.04, linux-image-4.4.0-1155-snapdragon, linux-image-virtual, linux-image-4.15.0-1113-azure, linux-image-virtual-hwe-16.04, linux-image-powerpc64-emb, linux-image-4.4.0-1151-raspi2, linux-image-powerpc64-smp-lts-utopic, linux-gcp-4.15, linux-image-gke, linux-image-virtual-lts-utopic, linux-image-powerpc-e500mc-lts-utopic, linux-image-generic-lpae-lts-xenial, linux-image-4.15.0-1090-kvm, linux-image-virtual-lts-xenial, linux-image-azure, linux-image-4.4.0-1091-aws, linux-image-4.15.0-1070-oracle, linux-image-4.15.0-1017-dell300x, linux-image-4.4.0-209-powerpc64-smp, linux-image-gcp, linux-image-4.4.0-1127-aws, linux-image-4.15.0-1098-gcp, linux-image-4.15.0-142-generic-lpae, linux-image-lowlatency-hwe-16.04, linux-image-powerpc64-smp-lts-wily, linux-image-powerpc64-smp-lts-xenial, linux-image-kvm, linux-azure-4.15, linux-image-powerpc-smp-lts-wily, linux-image-4.15.0-142-lowlatency, linux-image-aws-lts-18.04, linux-image-4.4.0-209-lowlatency, linux-image-generic-hwe-16.04, linux-raspi2, linux-image-oem, linux-image-generic-lpae-hwe-16.04-edge, linux-image-powerpc-smp, linux-image-lowlatency, linux-image-generic-lpae-lts-utopic, linux-image-azure-edge, linux-image-4.15.0-1099-aws, linux-image-powerpc64-smp-lts-vivid, linux-image-generic-lts-xenial, linux-image-powerpc64-smp, linux-image-virtual-hwe-16.04-edge, linux-image-generic-lpae-lts-wily, linux-image-dell300x, linux-image-generic, linux-image-generic-lts-vivid, linux-image-oracle, linux-image-powerpc-e500mc-lts-vivid, linux-image-4.4.0-209-generic, linux-image-aws-hwe, linux-image-aws, linux-image-lowlatency-lts-vivid, linux-image-powerpc-e500mc, linux-image-powerpc-e500mc-lts-xenial, linux-image-generic-lpae-lts-vivid, linux-image-lowlatency-lts-wily, linux-oracle, linux-azure, linux-image-lowlatency-lts-xenial, linux-image-powerpc-e500mc-lts-wily, linux-image-generic-lpae, linux-image-4.4.0-209-powerpc-e500mc, linux-image-4.4.0-1092-kvm, linux-image-4.4.0-209-powerpc64-emb, linux-aws, linux-image-generic-lpae-hwe-16.04, linux-image-4.15.0-1101-snapdragon, linux-image-powerpc64-emb-lts-utopic, linux-image-oracle-lts-18.04, linux-image-snapdragon, linux-image-powerpc64-emb-lts-xenial, linux-image-4.15.0-142-generic, linux-lts-xenial, linux-image-4.4.0-209-powerpc-smp, linux-image-4.4.0-209-generic-lpae, linux-image-powerpc64-emb-lts-wily, linux-image-gcp-lts-18.04, linux-image-lowlatency-lts-utopic, linux-image-raspi2, linux-gcp, linux-image-generic-lts-utopic, linux-hwe, linux, linux-image-powerpc-smp-lts-vivid, linux-snapdragon, linux-image-4.15.0-1084-raspi2, linux-image-powerpc-smp-lts-xenial, linux-image-generic-hwe-16.04-edge
• USN-4917-1: linux-image-generic-lpae-hwe-20.04, linux-image-raspi2-hwe-18.04-edge, linux-image-gkeop-5.4, linux-image-5.4.0-1043-oracle, linux-gke-5.3, linux-image-lowlatency-hwe-18.04, linux-image-virtual-hwe-18.04, linux-image-generic-lpae-hwe-18.04-edge, linux-gcp-5.4, linux-kvm, linux-image-5.8.0-50-generic-lpae, linux-image-virtual-hwe-18.04-edge, linux-image-5.3.0-1042-gke, linux-raspi2-5.3, linux-image-oem-20.04-edge, linux-image-generic-hwe-18.04-edge, linux-image-5.4.0-72-generic-lpae, linux-image-5.8.0-50-lowlatency, linux-image-oem-20.04, linux-image-5.4.0-1014-gkeop, linux-image-5.8.0-50-generic-64k, linux-image-5.8.0-1021-raspi, linux-image-virtual, linux-image-5.8.0-1030-aws, linux-image-5.8.0-1029-azure, linux-image-5.8.0-1028-gcp, linux-image-gkeop, linux-azure-5.4, linux-image-gke, linux-hwe-5.8, linux-image-generic-hwe-18.04, linux-image-gcp-edge, linux-image-5.3.0-73-lowlatency, linux-image-5.8.0-50-generic, linux-image-raspi-hwe-18.04-edge, linux-image-virtual-hwe-20.04, linux-image-5.3.0-73-generic, linux-oem-5.10, linux-image-5.8.0-1024-kvm, linux-oracle-5.4, linux-image-azure, linux-image-5.4.0-1046-azure, linux-image-5.4.0-1038-kvm, linux-raspi-5.4, linux-image-generic-64k-hwe-20.04-edge, linux-image-oracle-edge, linux-image-gcp, linux-image-raspi-hwe-18.04, linux-image-5.3.0-1039-raspi2, linux-image-kvm, linux-hwe-5.4, linux-image-lowlatency-hwe-20.04-edge, linux-image-gkeop-5.3, linux-image-virtual-hwe-20.04-edge, linux-gkeop-5.4, linux-image-raspi-nolpae, linux-image-oem, linux-image-lowlatency, linux-image-aws-edge, linux-image-azure-edge, linux-gkeop, linux-image-generic, linux-image-oracle, linux-image-snapdragon-hwe-18.04, linux-image-5.10.0-1022-oem, linux-image-oem-osp1, linux-image-5.4.0-1034-raspi, linux-image-generic-lpae-hwe-20.04-edge, linux-image-aws, linux-image-generic-lpae-hwe-18.04, linux-image-generic-64k-hwe-20.04, linux-gke-5.4, linux-oracle, linux-azure, linux-image-oem-20.04b, linux-image-generic-lpae, linux-image-5.4.0-1042-gke, linux-image-raspi2-hwe-18.04, linux-image-5.4.0-1042-gcp, linux-image-raspi, linux-image-5.8.0-1026-oracle, linux-aws, linux-image-generic-64k, linux-image-5.8.0-1021-raspi-nolpae, linux-image-gke-5.4, linux-aws-5.4, linux-image-gke-5.3, linux-image-generic-hwe-20.04, linux-image-snapdragon-hwe-18.04-edge, linux-image-raspi2, linux-gcp, linux-hwe, linux, linux-image-lowlatency-hwe-20.04, linux-image-5.4.0-72-generic, linux-image-5.4.0-72-lowlatency, linux-image-generic-hwe-20.04-edge, linux-raspi, linux-image-5.4.0-1045-aws, linux-image-lowlatency-hwe-18.04-edge
• LSN-0076-1: gke-4.15, oem, generic-4.15, gkeop, gke, gkeop-5.4, aws, lowlatency-5.4, generic-4.4, azure, lowlatency-4.4, gcp, generic-5.4, gke-5.4, lowlatency-4.15
• LSN-0077-1: gkeop, gke, gkeop-5.4, lowlatency-5.4, gcp, generic-5.4, gke-5.4