========================================================================== Ubuntu Security Notice USN-4751-1 February 25, 2021 linux, linux-aws, linux-azure, linux-gcp, linux-hwe-5.8, linux-kvm, linux-oracle, linux-raspi vulnerabilities ========================================================================== A security issue affects these releases of Ubuntu and its derivatives: - Ubuntu 20.10 - Ubuntu 20.04 LTS Summary: Several security issues were fixed in the Linux 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-kvm: Linux kernel for cloud environments - linux-oracle: Linux kernel for Oracle Cloud systems - linux-raspi: Linux kernel for Raspberry Pi (V8) systems - linux-hwe-5.8: Linux hardware enablement (HWE) kernel Details: It was discovered that the console keyboard driver in the Linux kernel contained a race condition. A local attacker could use this to expose sensitive information (kernel memory). (CVE-2020-25656) Minh Yuan discovered that the tty driver in the Linux kernel contained race conditions when handling fonts. A local attacker could possibly use this to expose sensitive information (kernel memory). (CVE-2020-25668) Bodong Zhao discovered a use-after-free in the Sun keyboard driver implementation in the Linux kernel. A local attacker could use this to cause a denial of service or possibly execute arbitrary code. (CVE-2020-25669) Kiyin (尹亮) discovered that the perf subsystem in the Linux kernel did not properly deallocate memory in some situations. A privileged attacker could use this to cause a denial of service (kernel memory exhaustion). (CVE-2020-25704) Julien Grall discovered that the Xen dom0 event handler in the Linux kernel did not properly limit the number of events queued. An attacker in a guest VM could use this to cause a denial of service in the host OS. (CVE-2020-27673) Jinoh Kang discovered that the Xen event channel infrastructure in the Linux kernel contained a race condition. An attacker in guest could possibly use this to cause a denial of service (dom0 crash). (CVE-2020-27675) Daniel Axtens discovered that PowerPC RTAS implementation in the Linux kernel did not properly restrict memory accesses in some situations. A privileged local attacker could use this to arbitrarily modify kernel memory, potentially bypassing kernel lockdown restrictions. (CVE-2020-27777) It was discovered that the jfs file system implementation in the Linux kernel contained an out-of-bounds read vulnerability. A local attacker could use this to possibly cause a denial of service (system crash). (CVE-2020-27815) Shisong Qin and Bodong Zhao discovered that Speakup screen reader driver in the Linux kernel did not correctly handle setting line discipline in some situations. A local attacker could use this to cause a denial of service (system crash). (CVE-2020-27830, CVE-2020-28941) It was discovered that a use-after-free vulnerability existed in the infiniband hfi1 device driver in the Linux kernel. A local attacker could possibly use this to cause a denial of service (system crash). (CVE-2020-27835) It was discovered that an information leak existed in the syscall implementation in the Linux kernel on 32 bit systems. A local attacker could use this to expose sensitive information (kernel memory). (CVE-2020-28588) Minh Yuan discovered that the framebuffer console driver in the Linux kernel did not properly handle fonts in some conditions. A local attacker could use this to cause a denial of service (system crash) or possibly expose sensitive information (kernel memory). (CVE-2020-28974) Michael Kurth and Pawel Wieczorkiewicz discovered that the Xen event processing backend in the Linux kernel did not properly limit the number of events queued. An attacker in a guest VM could use this to cause a denial of service in the host OS. (CVE-2020-29568) Olivier Benjamin and Pawel Wieczorkiewicz discovered a race condition the Xen paravirt block backend in the Linux kernel, leading to a use-after-free vulnerability. An attacker in a guest VM could use this to cause a denial of service in the host OS. (CVE-2020-29569) 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) It was discovered that a race condition existed that caused the Linux kernel to not properly restrict exit signal delivery. A local attacker could possibly use this to send signals to arbitrary processes. (CVE-2020-35508) Update instructions: The problem can be corrected by updating your system to the following package versions: Ubuntu 20.10: linux-image-5.8.0-1016-raspi 5.8.0-1016.19 linux-image-5.8.0-1016-raspi-nolpae 5.8.0-1016.19 linux-image-5.8.0-1019-kvm 5.8.0-1019.21 linux-image-5.8.0-1021-oracle 5.8.0-1021.22 linux-image-5.8.0-1023-azure 5.8.0-1023.25 linux-image-5.8.0-1023-gcp 5.8.0-1023.24 linux-image-5.8.0-1024-aws 5.8.0-1024.26 linux-image-5.8.0-44-generic 5.8.0-44.50 linux-image-5.8.0-44-generic-64k 5.8.0-44.50 linux-image-5.8.0-44-generic-lpae 5.8.0-44.50 linux-image-5.8.0-44-lowlatency 5.8.0-44.50 linux-image-aws 5.8.0.1024.26 linux-image-azure 5.8.0.1023.23 linux-image-gcp 5.8.0.1023.23 linux-image-generic 5.8.0.44.49 linux-image-generic-64k 5.8.0.44.49 linux-image-generic-lpae 5.8.0.44.49 linux-image-gke 5.8.0.1023.23 linux-image-kvm 5.8.0.1019.21 linux-image-lowlatency 5.8.0.44.49 linux-image-oem-20.04 5.8.0.44.49 linux-image-oracle 5.8.0.1021.20 linux-image-raspi 5.8.0.1016.19 linux-image-raspi-nolpae 5.8.0.1016.19 linux-image-virtual 5.8.0.44.49 Ubuntu 20.04 LTS: linux-image-5.8.0-44-generic 5.8.0-44.50~20.04.1 linux-image-5.8.0-44-generic-lpae 5.8.0-44.50~20.04.1 linux-image-5.8.0-44-lowlatency 5.8.0-44.50~20.04.1 linux-image-generic-64k-hwe-20.04 5.8.0.44.50~20.04.30 linux-image-generic-hwe-20.04 5.8.0.44.50~20.04.30 linux-image-generic-lpae-hwe-20.04 5.8.0.44.50~20.04.30 linux-image-lowlatency-hwe-20.04 5.8.0.44.50~20.04.30 linux-image-virtual-hwe-20.04 5.8.0.44.50~20.04.30 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: https://usn.ubuntu.com/4751-1 CVE-2020-25656, CVE-2020-25668, CVE-2020-25669, CVE-2020-25704, CVE-2020-27673, CVE-2020-27675, CVE-2020-27777, CVE-2020-27815, CVE-2020-27830, CVE-2020-27835, CVE-2020-28588, CVE-2020-28941, CVE-2020-28974, CVE-2020-29568, CVE-2020-29569, CVE-2020-29660, CVE-2020-29661, CVE-2020-35508 Package Information: https://launchpad.net/ubuntu/+source/linux/5.8.0-44.50 https://launchpad.net/ubuntu/+source/linux-aws/5.8.0-1024.26 https://launchpad.net/ubuntu/+source/linux-azure/5.8.0-1023.25 https://launchpad.net/ubuntu/+source/linux-gcp/5.8.0-1023.24 https://launchpad.net/ubuntu/+source/linux-kvm/5.8.0-1019.21 https://launchpad.net/ubuntu/+source/linux-oracle/5.8.0-1021.22 https://launchpad.net/ubuntu/+source/linux-raspi/5.8.0-1016.19 https://launchpad.net/ubuntu/+source/linux-hwe-5.8/5.8.0-44.50~20.04.1