7.8 - USN-3742-1

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

- Ubuntu 14.04 LTS

Summary:

Several security issues were fixed in the Linux kernel.

Software Description: - linux: Linux kernel

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 14.04 LTS:
linux-image-3.13.0-155-generic 3.13.0-155.205
linux-image-3.13.0-155-generic-lpae 3.13.0-155.205
linux-image-3.13.0-155-lowlatency 3.13.0-155.205
linux-image-3.13.0-155-powerpc-e500 3.13.0-155.205
linux-image-3.13.0-155-powerpc-e500mc 3.13.0-155.205
linux-image-3.13.0-155-powerpc-smp 3.13.0-155.205
linux-image-3.13.0-155-powerpc64-emb 3.13.0-155.205
linux-image-3.13.0-155-powerpc64-smp 3.13.0-155.205
linux-image-generic 3.13.0.155.165
linux-image-generic-lpae 3.13.0.155.165
linux-image-lowlatency 3.13.0.155.165
linux-image-powerpc-e500 3.13.0.155.165
linux-image-powerpc-e500mc 3.13.0.155.165
linux-image-powerpc-smp 3.13.0.155.165
linux-image-powerpc64-emb 3.13.0.155.165
linux-image-powerpc64-smp 3.13.0.155.165

Please note that the recommended mitigation for CVE-2018-3646 involves updating processor microcode in addition to updating the kernel; however, the kernel includes a fallback for processors that have not received microcode updates.

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:
https://usn.ubuntu.com/usn/usn-3742-1
CVE-2017-18344, CVE-2018-3620, CVE-2018-3646, CVE-2018-5390,
CVE-2018-5391,
https://wiki.ubuntu.com/SecurityTeam/KnowledgeBase/L1TF

Package Information:
https://launchpad.net/ubuntu/+source/linux/3.13.0-155.205