========================================================================= Ubuntu Security Notice USN-5210-2 January 12, 2022 linux, linux-gcp, linux-gcp-5.4, linux-hwe-5.4 regression ========================================================================= A security issue affects these releases of Ubuntu and its derivatives: - Ubuntu 20.04 LTS - Ubuntu 18.04 LTS Summary: USN-5210-1 introduced a regression in the Linux kernel. Software Description: - linux: Linux kernel - linux-gcp: Linux kernel for Google Cloud Platform (GCP) systems - linux-gcp-5.4: Linux kernel for Google Cloud Platform (GCP) systems - linux-hwe-5.4: Linux hardware enablement (HWE) kernel Details: USN-5210-1 fixed vulnerabilities in the Linux kernel. Unfortunately, that update introduced a regression that caused failures to boot in environments with AMD Secure Encrypted Virtualization (SEV) enabled. This update fixes the problem. We apologize for the inconvenience. Original advisory details: Nadav Amit discovered that the hugetlb implementation in the Linux kernel did not perform TLB flushes under certain conditions. A local attacker could use this to leak or alter data from other processes that use huge pages. (CVE-2021-4002) It was discovered that the Linux kernel did not properly enforce certain types of entries in the Secure Boot Forbidden Signature Database (aka dbx) protection mechanism. An attacker could use this to bypass UEFI Secure Boot restrictions. (CVE-2020-26541) It was discovered that a race condition existed in the overlay file system implementation in the Linux kernel. A local attacker could use this to cause a denial of service (system crash). (CVE-2021-20321) It was discovered that the NFC subsystem in the Linux kernel contained a use-after-free vulnerability in its NFC Controller Interface (NCI) implementation. A local attacker could possibly use this to cause a denial of service (system crash) or execute arbitrary code. (CVE-2021-3760) It was discovered that an integer overflow could be triggered in the eBPF implementation in the Linux kernel when preallocating objects for stack maps. A privileged local attacker could use this to cause a denial of service or possibly execute arbitrary code. (CVE-2021-41864) It was discovered that the KVM implementation for POWER8 processors in the Linux kernel did not properly keep track if a wakeup event could be resolved by a guest. An attacker in a guest VM could possibly use this to cause a denial of service (host OS crash). (CVE-2021-43056) It was discovered that the ISDN CAPI implementation in the Linux kernel contained a race condition in certain situations that could trigger an array out-of-bounds bug. A privileged local attacker could possibly use this to cause a denial of service or execute arbitrary code. (CVE-2021-43389) Update instructions: The problem can be corrected by updating your system to the following package versions: Ubuntu 20.04 LTS: linux-image-5.4.0-1060-gcp 5.4.0-1060.64 linux-image-5.4.0-94-generic 5.4.0-94.106 linux-image-5.4.0-94-generic-lpae 5.4.0-94.106 linux-image-5.4.0-94-lowlatency 5.4.0-94.106 linux-image-gcp-lts-20.04 5.4.0.1060.70 linux-image-generic 5.4.0.94.98 linux-image-generic-lpae 5.4.0.94.98 linux-image-lowlatency 5.4.0.94.98 linux-image-oem 5.4.0.94.98 linux-image-oem-osp1 5.4.0.94.98 linux-image-virtual 5.4.0.94.98 Ubuntu 18.04 LTS: linux-image-5.4.0-1060-gcp 5.4.0-1060.64~18.04.1 linux-image-5.4.0-94-generic 5.4.0-94.106~18.04.1 linux-image-5.4.0-94-generic-lpae 5.4.0-94.106~18.04.1 linux-image-5.4.0-94-lowlatency 5.4.0-94.106~18.04.1 linux-image-gcp 5.4.0.1060.46 linux-image-generic-hwe-18.04 5.4.0.94.106~18.04.83 linux-image-generic-lpae-hwe-18.04 5.4.0.94.106~18.04.83 linux-image-lowlatency-hwe-18.04 5.4.0.94.106~18.04.83 linux-image-oem 5.4.0.94.106~18.04.83 linux-image-oem-osp1 5.4.0.94.106~18.04.83 linux-image-snapdragon-hwe-18.04 5.4.0.94.106~18.04.83 linux-image-virtual-hwe-18.04 5.4.0.94.106~18.04.83 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://ubuntu.com/security/notices/USN-5210-2 https://ubuntu.com/security/notices/USN-5210-1 https://launchpad.net/bugs/1956575 Package Information: https://launchpad.net/ubuntu/+source/linux/5.4.0-94.106 https://launchpad.net/ubuntu/+source/linux-gcp/5.4.0-1060.64 https://launchpad.net/ubuntu/+source/linux-gcp-5.4/5.4.0-1060.64~18.04.1 https://launchpad.net/ubuntu/+source/linux-hwe-5.4/5.4.0-94.106~18.04.1