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USN-4916-1: Linux kernel vulnerabilities

15 April 2021

Several security issues were fixed in the Linux kernel.

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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)

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Ubuntu Pro provides ten-year security coverage to 25,000+ packages in Main and Universe repositories, and it is free for up to five machines.

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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.

References

Related notices

  • USN-4915-1: linux-image-5.6.0-1054-oem, linux-oem-5.6, linux-image-oem-20.04
  • USN-4917-1: linux-image-gke, linux-image-gke-5.3, linux-image-5.3.0-1042-gke, linux-oem-5.10, linux-image-raspi2-hwe-18.04, linux, linux-image-lowlatency, linux-image-azure, linux-image-lowlatency-hwe-18.04, linux-image-5.3.0-1039-raspi2, linux-image-virtual-hwe-18.04, linux-image-5.3.0-73-generic, linux-image-5.4.0-1042-gke, linux-image-5.8.0-50-generic-lpae, linux-image-oem-20.04b, linux-image-generic-64k-hwe-20.04, linux-image-5.4.0-1045-aws, linux-image-5.4.0-72-generic-lpae, linux-image-raspi, linux-image-kvm, linux-image-raspi-hwe-18.04, linux-gkeop, linux-image-generic-hwe-18.04, linux-image-5.4.0-1014-gkeop, linux-image-generic-hwe-20.04, linux-hwe, linux-image-5.4.0-1042-gcp, linux-image-generic-lpae-hwe-18.04-edge, linux-kvm, linux-image-generic-64k-hwe-20.04-edge, linux-image-5.4.0-1043-oracle, linux-image-snapdragon-hwe-18.04, linux-image-generic-hwe-18.04-edge, linux-image-oem-20.04-edge, linux-hwe-5.8, linux-image-lowlatency-hwe-18.04-edge, linux-image-virtual-hwe-20.04, linux-image-virtual-hwe-18.04-edge, linux-oracle, linux-image-generic-lpae, linux-image-oem, linux-raspi2-5.3, linux-image-gkeop-5.3, linux-image-5.4.0-72-generic, linux-image-raspi2, linux-image-virtual-hwe-20.04-edge, linux-image-5.3.0-73-lowlatency, linux-aws, linux-image-raspi2-hwe-18.04-edge, linux-image-5.8.0-1021-raspi-nolpae, linux-image-generic-lpae-hwe-18.04, linux-image-virtual, linux-image-gcp, linux-image-snapdragon-hwe-18.04-edge, linux-image-5.8.0-1024-kvm, linux-image-azure-edge, linux-image-5.4.0-1034-raspi, linux-image-gke-5.4, linux-gkeop-5.4, linux-image-aws-edge, linux-image-5.4.0-1046-azure, linux-image-aws, linux-image-generic-lpae-hwe-20.04-edge, linux-image-5.4.0-1038-kvm, linux-image-oem-20.04, linux-oracle-5.4, linux-azure-5.4, linux-image-5.4.0-72-lowlatency, linux-image-oracle, linux-image-5.8.0-50-generic-64k, linux-image-generic-lpae-hwe-20.04, linux-gcp-5.4, linux-image-lowlatency-hwe-20.04-edge, linux-image-generic-64k, linux-aws-5.4, linux-image-lowlatency-hwe-20.04, linux-image-5.8.0-50-generic, linux-image-raspi-hwe-18.04-edge, linux-image-5.8.0-1028-gcp, linux-image-generic, linux-image-gkeop, linux-raspi, linux-azure, linux-gke-5.3, linux-image-5.8.0-1021-raspi, linux-raspi-5.4, linux-image-generic-hwe-20.04-edge, linux-hwe-5.4, linux-gcp, linux-gke-5.4, linux-image-gkeop-5.4, linux-image-5.8.0-1026-oracle, linux-image-oem-osp1, linux-image-5.10.0-1022-oem, linux-image-5.8.0-1030-aws, linux-image-gcp-edge, linux-image-5.8.0-1029-azure, linux-image-raspi-nolpae, linux-image-oracle-edge, linux-image-5.8.0-50-lowlatency
  • LSN-0076-1: gcp, generic-5.4, gke, generic-4.4, lowlatency-5.4, gkeop, aws, lowlatency-4.15, azure, lowlatency-4.4, oem, gke-4.15, generic-4.15, gkeop-5.4, gke-5.4
  • USN-4912-1: linux-oem-5.6, linux-image-5.6.0-1053-oem, linux-image-oem-20.04

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