USN-3742-3: Linux kernel (Trusty HWE) regressions

21 August 2018

linux-lts-trusty regressions

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

  • Ubuntu 12.04 ESM

Summary

USN-3742-2 introduced regressions in the Linux Hardware Enablement (HWE) kernel for Ubuntu 12.04 ESM.

Software Description

  • linux-lts-trusty - Linux hardware enablement kernel from Trusty for Precise ESM

Details

USN-3742-2 introduced mitigations in the Linux Hardware Enablement (HWE) kernel for Ubuntu 12.04 ESM to address L1 Terminal Fault (L1TF) vulnerabilities (CVE-2018-3620, CVE-2018-3646). Unfortunately, the update introduced regressions that caused kernel panics when booting in some environments as well as preventing Java applications from starting. This update fixes the problems.

We apologize for the inconvenience.

Original advisory details:

It was discovered that memory present in the L1 data cache of an Intel CPU core may be exposed to a malicious process that is executing on the CPU core. This vulnerability is also known as L1 Terminal Fault (L1TF). A local attacker in a guest virtual machine could use this to expose sensitive information (memory from other guests or the host OS). (CVE-2018-3646)

It was discovered that memory present in the L1 data cache of an Intel CPU core may be exposed to a malicious process that is executing on the CPU core. This vulnerability is also known as L1 Terminal Fault (L1TF). A local attacker could use this to expose sensitive information (memory from the kernel or other processes). (CVE-2018-3620)

Andrey Konovalov discovered an out-of-bounds read in the POSIX timers subsystem in the Linux kernel. A local attacker could use this to cause a denial of service (system crash) or expose sensitive information. (CVE-2017-18344)

Juha-Matti Tilli discovered that the TCP implementation in the Linux kernel performed algorithmically expensive operations in some situations when handling incoming packets. A remote attacker could use this to cause a denial of service. (CVE-2018-5390)

Juha-Matti Tilli discovered that the IP implementation in the Linux kernel performed algorithmically expensive operations in some situations when handling incoming packet fragments. A remote attacker could use this to cause a denial of service. (CVE-2018-5391)

Update instructions

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

Ubuntu 12.04 ESM
linux-image-3.13.0-156-generic - 3.13.0-156.206~precise1
linux-image-3.13.0-156-generic-lpae - 3.13.0-156.206~precise1
linux-image-generic-lpae-lts-trusty - 3.13.0.156.146
linux-image-generic-lts-trusty - 3.13.0.156.146

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