[LSN-0082-1] 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 ESM
Summary
Several security issues were fixed in the kernel.
Software Description
– linux – Linux kernel – 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
Jann Horn discovered that the tty subsystem of the Linux kernel did not use consistent locking in some situations, leading to a read-after-free vulnerability. A local attacker could use this to cause a denial of service (system crash) or possibly expose sensitive information (kernel memory). (CVE-2020-29660)
Jann Horn discovered a race condition in the tty subsystem of the Linux kernel in the locking for the TIOCSPGRP ioctl(), leading to a use-after- free vulnerability. A local attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code. (CVE-2020-29661)
De4dCr0w of 360 Alpha Lab discovered that the BPF verifier in the Linux kernel did not properly handle mod32 destination register truncation when the source register was known to be 0. A local attacker could use this to expose sensitive information (kernel memory) or possibly execute arbitrary code. (CVE-2021-3444)
kernel: use-after-free in route4_change() in net/sched/cls_route.c (CVE-2021-3715)
Update instructions
The problem can be corrected by updating your kernel livepatch to the following versions:
Ubuntu 20.04 LTS gcp – 82.2 generic – 82.2 gke – 82.2 gkeop – 82.2 lowlatency – 82.2
Ubuntu 18.04 LTS generic – 82.1 generic – 82.2 gke – 82.1 gke – 82.2 gkeop – 82.2 lowlatency – 82.1 lowlatency – 82.2 oem – 82.1 oem – 82.2
Ubuntu 16.04 ESM generic – 82.1 generic – 82.2 lowlatency – 82.1 lowlatency – 82.2
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-azure-4.15 – 4.15.0-1115 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 ESM linux-aws – 4.4.0-1098 linux-azure – 4.15.0-1063 linux-hwe – 4.15.0-69 linux – 4.4.0-168
Ubuntu 14.04 ESM linux-lts-xenial – 4.4.0-168
References
– CVE-2020-29660 – CVE-2020-29661 – CVE-2021-3444 – CVE-2021-3715