USN-3582-1: Linux kernel vulnerabilities

22 February 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

Mohamed Ghannam discovered that the IPv4 raw socket implementation in the Linux kernel contained a race condition leading to uninitialized pointer usage. A local attacker could use this to cause a denial of service or possibly execute arbitrary code. (CVE-2017-17712)

Laurent Guerby discovered that the mbcache feature in the ext2 and ext4 filesystems in the Linux kernel improperly handled xattr block caching. A local attacker could use this to cause a denial of service. (CVE-2015-8952)

Vitaly Mayatskikh discovered that the SCSI subsystem in the Linux kernel did not properly track reference counts when merging buffers. A local attacker could use this to cause a denial of service (memory exhaustion). (CVE-2017-12190)

ChunYu Wang discovered that a use-after-free vulnerability existed in the SCTP protocol 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-2017-15115)

Mohamed Ghannam discovered a use-after-free vulnerability in the DCCP protocol 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-2017-8824)

USN-3540-1 mitigated CVE-2017-5715 (Spectre Variant 2) for the amd64 architecture in Ubuntu 16.04 LTS. This update provides the compiler-based retpoline kernel mitigation for the amd64 and i386 architectures. Original advisory details:

Jann Horn discovered that microprocessors utilizing speculative execution and branch prediction may allow unauthorized memory reads via sidechannel attacks. This flaw is known as Spectre. A local attacker could use this to expose sensitive information, including kernel memory. (CVE-2017-5715)

Update instructions

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

Ubuntu 16.04 LTS
linux-image-4.4.0-1019-kvm - 4.4.0-1019.24
linux-image-4.4.0-1052-aws - 4.4.0-1052.61
linux-image-4.4.0-1085-raspi2 - 4.4.0-1085.93
linux-image-4.4.0-1087-snapdragon - 4.4.0-1087.92
linux-image-4.4.0-116-generic - 4.4.0-116.140
linux-image-4.4.0-116-generic-lpae - 4.4.0-116.140
linux-image-4.4.0-116-lowlatency - 4.4.0-116.140
linux-image-4.4.0-116-powerpc-e500mc - 4.4.0-116.140
linux-image-4.4.0-116-powerpc-smp - 4.4.0-116.140
linux-image-4.4.0-116-powerpc64-emb - 4.4.0-116.140
linux-image-4.4.0-116-powerpc64-smp - 4.4.0-116.140
linux-image-aws - 4.4.0.1052.54
linux-image-generic - 4.4.0.116.122
linux-image-generic-lpae - 4.4.0.116.122
linux-image-kvm - 4.4.0.1019.18
linux-image-lowlatency - 4.4.0.116.122
linux-image-powerpc-e500mc - 4.4.0.116.122
linux-image-powerpc-smp - 4.4.0.116.122
linux-image-powerpc64-emb - 4.4.0.116.122
linux-image-powerpc64-smp - 4.4.0.116.122
linux-image-raspi2 - 4.4.0.1085.85
linux-image-snapdragon - 4.4.0.1087.79

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