USN-4916-1: Linux kernel vulnerabilities

15 April 2021

Several security issues were fixed in the Linux kernel.

Releases

Packages

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)

Piotr Krysiuk discovered that the BPF JIT compiler for x86 in the Linux
kernel did not properly validate computation of branch displacements in
some situations. A local attacker could use this to cause a denial of
service (system crash) or possibly execute arbitrary code. (CVE-2021-29154)

Update instructions

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

Ubuntu 18.04
Ubuntu 16.04
Ubuntu 14.04

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-oem-5.6, linux-image-oem-20.04
  • LSN-0076-1: lowlatency-5.4, gkeop, gke-4.15, azure, gcp, generic-5.4, generic-4.15, generic-4.4, gke, gkeop-5.4, lowlatency-4.4, aws, lowlatency-4.15, oem, gke-5.4
  • USN-4917-1: linux-image-gke-5.4, linux-image-5.4.0-72-generic, linux-hwe-5.4, linux-image-raspi-hwe-18.04, linux-image-gkeop-5.4, linux-image-5.4.0-1014-gkeop, linux-image-oem-20.04b, linux-image-5.4.0-1046-azure, linux-image-gke-5.3, linux-kvm, linux-image-oracle, linux-image-generic, linux-image-gke, linux-image-5.4.0-1038-kvm, linux-image-gcp, linux-image-5.10.0-1022-oem, linux-image-generic-lpae, linux-image-raspi-hwe-18.04-edge, linux-image-5.8.0-50-generic, linux-image-lowlatency, linux-image-raspi2, linux-image-5.4.0-1043-oracle, linux-image-5.8.0-1028-gcp, linux-aws, linux-image-generic-64k-hwe-20.04-edge, linux-image-gkeop-5.3, linux-image-generic-hwe-18.04, linux-image-5.4.0-1042-gcp, linux-image-virtual-hwe-20.04, linux-gcp-5.4, linux-image-azure-edge, linux-image-5.3.0-73-generic, linux-gkeop-5.4, linux-image-5.8.0-1021-raspi-nolpae, linux-image-lowlatency-hwe-18.04, linux-image-generic-lpae-hwe-18.04, linux-image-generic-hwe-18.04-edge, linux-image-raspi2-hwe-18.04-edge, linux-image-oracle-edge, linux-image-oem-20.04, linux-image-5.8.0-1029-azure, linux-image-5.4.0-72-lowlatency, linux-image-generic-64k, linux-image-oem-20.04-edge, linux-image-oem-osp1, linux-image-gcp-edge, linux-azure-5.4, linux-image-5.8.0-1021-raspi, linux-gcp, linux-hwe, linux-image-5.4.0-72-generic-lpae, linux-image-snapdragon-hwe-18.04, linux-image-generic-hwe-20.04, linux-image-generic-64k-hwe-20.04, linux-image-lowlatency-hwe-20.04-edge, linux-image-generic-lpae-hwe-20.04, linux-oracle-5.4, linux-image-5.4.0-1045-aws, linux-image-lowlatency-hwe-18.04-edge, linux-image-virtual-hwe-18.04, linux-image-generic-hwe-20.04-edge, linux-image-5.3.0-73-lowlatency, linux-image-virtual, linux-image-aws, linux-gkeop, linux-aws-5.4, linux, linux-image-5.8.0-50-generic-64k, linux-image-5.4.0-1042-gke, linux-image-raspi2-hwe-18.04, linux-raspi, linux-oem-5.10, linux-image-generic-lpae-hwe-18.04-edge, linux-image-gkeop, linux-image-azure, linux-image-5.8.0-1026-oracle, linux-oracle, linux-image-raspi, linux-image-aws-edge, linux-image-5.8.0-50-generic-lpae, linux-image-kvm, linux-image-virtual-hwe-18.04-edge, linux-image-snapdragon-hwe-18.04-edge, linux-raspi2-5.3, linux-image-5.3.0-1039-raspi2, linux-raspi-5.4, linux-image-raspi-nolpae, linux-azure, linux-image-5.8.0-1024-kvm, linux-hwe-5.8, linux-image-5.8.0-1030-aws, linux-gke-5.4, linux-image-oem, linux-gke-5.3, linux-image-generic-lpae-hwe-20.04-edge, linux-image-lowlatency-hwe-20.04, linux-image-5.3.0-1042-gke, linux-image-5.4.0-1034-raspi, linux-image-5.8.0-50-lowlatency, linux-image-virtual-hwe-20.04-edge
  • USN-4915-1: linux-image-5.6.0-1054-oem, linux-oem-5.6, linux-image-oem-20.04