[USN-4876-1] Linux kernel vulnerabilities

========================================================================== Ubuntu Security Notice USN-4876-1 March 16, 2021
linux, linux-aws, linux-kvm, linux-lts-xenial, linux-raspi2, linux-snapdragon vulnerabilities ==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:
– Ubuntu 16.04 LTS – Ubuntu 14.04 ESM
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-kvm: Linux kernel for cloud environments – linux-raspi2: Linux kernel for Raspberry Pi (V8) systems – linux-snapdragon: Linux kernel for Qualcomm Snapdragon processors – linux-lts-xenial: Linux hardware enablement kernel from Xenial for Trusty
Details:
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)
It was discovered that the Marvell WiFi-Ex device driver in the Linux kernel did not properly validate ad-hoc SSIDs. A local attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code. (CVE-2020-36158)
吴异 discovered that the NFS implementation in the Linux kernel did not properly prevent access outside of an NFS export that is a subdirectory of a file system. An attacker could possibly use this to bypass NFS access restrictions. (CVE-2021-3178)
Update instructions:
The problem can be corrected by updating your system to the following package versions:
Ubuntu 16.04 LTS: linux-image-4.4.0-1089-kvm 4.4.0-1089.98 linux-image-4.4.0-1123-aws 4.4.0-1123.137 linux-image-4.4.0-1147-raspi2 4.4.0-1147.157 linux-image-4.4.0-1151-snapdragon 4.4.0-1151.161 linux-image-4.4.0-204-generic 4.4.0-204.236 linux-image-4.4.0-204-generic-lpae 4.4.0-204.236 linux-image-4.4.0-204-lowlatency 4.4.0-204.236 linux-image-4.4.0-204-powerpc-e500mc 4.4.0-204.236 linux-image-4.4.0-204-powerpc-smp 4.4.0-204.236 linux-image-4.4.0-204-powerpc64-emb 4.4.0-204.236 linux-image-4.4.0-204-powerpc64-smp 4.4.0-204.236 linux-image-aws 4.4.0.1123.128 linux-image-generic 4.4.0.204.210 linux-image-generic-lpae 4.4.0.204.210 linux-image-kvm 4.4.0.1089.87 linux-image-lowlatency 4.4.0.204.210 linux-image-powerpc-e500mc 4.4.0.204.210 linux-image-powerpc-smp 4.4.0.204.210 linux-image-powerpc64-emb 4.4.0.204.210 linux-image-powerpc64-smp 4.4.0.204.210 linux-image-raspi2 4.4.0.1147.147 linux-image-snapdragon 4.4.0.1151.143 linux-image-virtual 4.4.0.204.210
Ubuntu 14.04 ESM: linux-image-4.4.0-1087-aws 4.4.0-1087.91 linux-image-4.4.0-204-generic 4.4.0-204.236~14.04.1 linux-image-4.4.0-204-generic-lpae 4.4.0-204.236~14.04.1 linux-image-4.4.0-204-lowlatency 4.4.0-204.236~14.04.1 linux-image-4.4.0-204-powerpc-e500mc 4.4.0-204.236~14.04.1 linux-image-4.4.0-204-powerpc-smp 4.4.0-204.236~14.04.1 linux-image-4.4.0-204-powerpc64-emb 4.4.0-204.236~14.04.1 linux-image-4.4.0-204-powerpc64-smp 4.4.0-204.236~14.04.1 linux-image-aws 4.4.0.1087.84 linux-image-generic-lpae-lts-xenial 4.4.0.204.178 linux-image-generic-lts-xenial 4.4.0.204.178 linux-image-lowlatency-lts-xenial 4.4.0.204.178 linux-image-powerpc-e500mc-lts-xenial 4.4.0.204.178 linux-image-powerpc-smp-lts-xenial 4.4.0.204.178 linux-image-powerpc64-emb-lts-xenial 4.4.0.204.178 linux-image-powerpc64-smp-lts-xenial 4.4.0.204.178 linux-image-virtual-lts-xenial 4.4.0.204.178
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: ubuntu.com/security/notices/USN-4876-1 CVE-2020-29569, CVE-2020-36158, CVE-2021-3178
Package Information: launchpad.net/ubuntu/+source/linux/4.4.0-204.236 launchpad.net/ubuntu/+source/linux-aws/4.4.0-1123.137 launchpad.net/ubuntu/+source/linux-kvm/4.4.0-1089.98 launchpad.net/ubuntu/+source/linux-raspi2/4.4.0-1147.157 launchpad.net/ubuntu/+source/linux-snapdragon/4.4.0-1151.161