USN-3777-2: Linux kernel (HWE) vulnerabilities
1 October 2018
linux-hwe, linux-gcp vulnerabilities
A security issue affects these releases of Ubuntu and its derivatives:
- Ubuntu 16.04 LTS
Several security issues were fixed in the Linux kernel.
- linux-gcp - Linux kernel for Google Cloud Platform (GCP) systems
- linux-hwe - Linux hardware enablement (HWE) kernel
USN-3777-1 fixed vulnerabilities in the Linux kernel for Ubuntu 18.04 LTS. This update provides the corresponding updates for the Linux Hardware Enablement (HWE) kernel from Ubuntu 18.04 LTS for Ubuntu 16.04 LTS.
Jann Horn discovered that the vmacache subsystem did not properly handle sequence number overflows, leading to a use-after-free vulnerability. A local attacker could use this to cause a denial of service (system crash) or execute arbitrary code. (CVE-2018-17182)
It was discovered that the paravirtualization implementation in the Linux kernel did not properly handle some indirect calls, reducing the effectiveness of Spectre v2 mitigations for paravirtual guests. A local attacker could use this to expose sensitive information. (CVE-2018-15594)
It was discovered that microprocessors utilizing speculative execution and prediction of return addresses via Return Stack Buffer (RSB) may allow unauthorized memory reads via sidechannel attacks. An attacker could use this to expose sensitive information. (CVE-2018-15572)
Andy Lutomirski and Mika Penttilä discovered that the KVM implementation in the Linux kernel did not properly check privilege levels when emulating some instructions. An unprivileged attacker in a guest VM could use this to escalate privileges within the guest. (CVE-2018-10853)
It was discovered that a stack-based buffer overflow existed in the iSCSI target implementation of the Linux kernel. A remote attacker could use this to cause a denial of service (system crash). (CVE-2018-14633)
It was discovered that a memory leak existed in the IRDA subsystem of the Linux kernel. A local attacker could use this to cause a denial of service (kernel memory exhaustion). (CVE-2018-6554)
It was discovered that a use-after-free vulnerability existed in the IRDA implementation in the Linux kernel. A local attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code. (CVE-2018-6555)
USN 3653-2 added a mitigation for Speculative Store Bypass a.k.a. Spectre Variant 4 (CVE-2018-3639). This update provides the corresponding mitigation for ARM64 processors. Please note that for this mitigation to be effective, an updated firmware for the processor may be required. ‘
The problem can be corrected by updating your system to the following package versions:
- Ubuntu 16.04 LTS
- linux-image-4.15.0-1021-gcp - 4.15.0-1021.22~16.04.1
- linux-image-4.15.0-36-generic - 4.15.0-36.39~16.04.1
- linux-image-4.15.0-36-generic-lpae - 4.15.0-36.39~16.04.1
- linux-image-4.15.0-36-lowlatency - 4.15.0-36.39~16.04.1
- linux-image-gcp - 188.8.131.521.35
- linux-image-generic-hwe-16.04 - 184.108.40.206.59
- linux-image-generic-lpae-hwe-16.04 - 220.127.116.11.59
- linux-image-gke - 18.104.22.1681.35
- linux-image-lowlatency-hwe-16.04 - 22.214.171.124.59
- linux-image-oem - 126.96.36.199.59
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.
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.