[LSN-0076-1] Linux kernel vulnerability

Linux kernel vulnerabilities
A security issue affects these releases of Ubuntu and its derivatives:
– Ubuntu 20.04 LTS – Ubuntu 18.04 LTS – Ubuntu 16.04 LTS – Ubuntu 14.04 ESM
Summary
Several security issues were fixed in the kernel.
Software Description
– 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-gke – Linux kernel for Google Container Engine (GKE) systems – linux-gkeop – Linux kernel for Google Container Engine (GKE) systems – linux-oem – 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)
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 kernel livepatch to the following versions:
Ubuntu 20.04 LTS aws – 76.3 azure – 76.3 gcp – 76.3 generic – 76.3 gke – 76.3 gkeop – 76.3 lowlatency – 76.3
Ubuntu 18.04 LTS aws – 76.2 generic – 76.3 gke – 76.3 gkeop – 76.3 lowlatency – 76.3 oem – 76.2
Ubuntu 16.04 LTS aws – 76.1 azure – 76.2 generic – 76.2 lowlatency – 76.2
Ubuntu 14.04 ESM generic – 76.1 lowlatency – 76.1
Support Information
Kernels older than the levels listed below do not receive livepatch updates. If you are running a kernel version earlier than the one listed below, please upgrade your kernel as soon as possible.
Ubuntu 20.04 LTS linux-aws – 5.4.0-1009 linux-azure – 5.4.0-1010 linux-gcp – 5.4.0-1009 linux-gke – 5.4.0-1033 linux-gkeop – 5.4.0-1009 linux-oem – 5.4.0-26 linux – 5.4.0-26
Ubuntu 18.04 LTS linux-aws – 4.15.0-1054 linux-gke-4.15 – 4.15.0-1076 linux-gke-5.4 – 5.4.0-1009 linux-gkeop-5.4 – 5.4.0-1007 linux-hwe-5.4 – 5.4.0-26 linux-oem – 4.15.0-1063 linux – 4.15.0-69
Ubuntu 16.04 LTS linux-aws – 4.4.0-1098 linux-azure – 4.15.0-1063 linux-azure – 4.15.0-1078 linux-hwe – 4.15.0-69 linux – 4.4.0-168
Ubuntu 14.04 ESM linux-lts-xenial – 4.4.0-168
References
– CVE-2021-3493 – CVE-2021-29154