USN-3821-1: Linux kernel vulnerabilities

14 November 2018

linux, linux-aws, linux-kvm, linux-raspi2, linux-snapdragon vulnerabilities

A security issue affects these releases of Ubuntu and its derivatives:

  • Ubuntu 16.04 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-kvm - Linux kernel for cloud environments
  • linux-raspi2 - Linux kernel for Raspberry Pi 2
  • linux-snapdragon - Linux kernel for Snapdragon processors

Details

Wen Xu discovered that the ext4 filesystem implementation in the Linux kernel did not properly ensure that xattr information remained in inode bodies. An attacker could use this to construct a malicious ext4 image that, when mounted, could cause a denial of service (system crash). (CVE-2018-10880)

It was discovered that the alarmtimer implementation in the Linux kernel contained an integer overflow vulnerability. A local attacker could use this to cause a denial of service. (CVE-2018-13053)

Wen Xu discovered that the f2fs filesystem implementation in the Linux kernel did not properly validate metadata. An attacker could use this to construct a malicious f2fs image that, when mounted, could cause a denial of service (system crash). (CVE-2018-13096)

Wen Xu and Po-Ning Tseng discovered that the btrfs filesystem implementation in the Linux kernel did not properly handle relocations in some situations. An attacker could use this to construct a malicious btrfs image that, when mounted, could cause a denial of service (system crash). (CVE-2018-14609)

Wen Xu discovered that the HFS+ filesystem implementation in the Linux kernel did not properly handle malformed catalog data in some situations. An attacker could use this to construct a malicious HFS+ image that, when mounted, could cause a denial of service (system crash). (CVE-2018-14617)

Jann Horn discovered that the procfs file system implementation in the Linux kernel did not properly restrict the ability to inspect the kernel stack of an arbitrary task. A local attacker could use this to expose sensitive information. (CVE-2018-17972)

It was discovered that the KVM implementation in the Linux kernel on ARM 64bit processors did not properly handle some ioctls. An attacker with the privilege to create KVM-based virtual machines could use this to cause a denial of service (host system crash) or execute arbitrary code in the host. (CVE-2018-18021)

Update instructions

The problem can be corrected by updating your system to the following package versions:

Ubuntu 16.04 LTS
linux-image-4.4.0-1037-kvm - 4.4.0-1037.43
linux-image-4.4.0-1072-aws - 4.4.0-1072.82
linux-image-4.4.0-1100-raspi2 - 4.4.0-1100.108
linux-image-4.4.0-1104-snapdragon - 4.4.0-1104.109
linux-image-4.4.0-139-generic - 4.4.0-139.165
linux-image-4.4.0-139-generic-lpae - 4.4.0-139.165
linux-image-4.4.0-139-lowlatency - 4.4.0-139.165
linux-image-4.4.0-139-powerpc-e500mc - 4.4.0-139.165
linux-image-4.4.0-139-powerpc-smp - 4.4.0-139.165
linux-image-4.4.0-139-powerpc64-emb - 4.4.0-139.165
linux-image-4.4.0-139-powerpc64-smp - 4.4.0-139.165
linux-image-aws - 4.4.0.1072.74
linux-image-generic - 4.4.0.139.145
linux-image-generic-lpae - 4.4.0.139.145
linux-image-kvm - 4.4.0.1037.36
linux-image-lowlatency - 4.4.0.139.145
linux-image-powerpc-e500mc - 4.4.0.139.145
linux-image-powerpc-smp - 4.4.0.139.145
linux-image-powerpc64-emb - 4.4.0.139.145
linux-image-powerpc64-smp - 4.4.0.139.145
linux-image-raspi2 - 4.4.0.1100.100
linux-image-snapdragon - 4.4.0.1104.96

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.

References