USN-3741-1: Linux kernel vulnerabilities

Releases

• Ubuntu 16.04 ESM

Packages

• 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

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)

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 16.04

• linux-image-4.4.0-1031-kvm - 4.4.0-1031.37
• linux-image-4.4.0-1065-aws - 4.4.0-1065.75
• linux-image-4.4.0-1094-raspi2 - 4.4.0-1094.102
• linux-image-4.4.0-1098-snapdragon - 4.4.0-1098.103
• linux-image-4.4.0-133-generic - 4.4.0-133.159
• linux-image-4.4.0-133-generic-lpae - 4.4.0-133.159
• linux-image-4.4.0-133-lowlatency - 4.4.0-133.159
• linux-image-4.4.0-133-powerpc-e500mc - 4.4.0-133.159
• linux-image-4.4.0-133-powerpc-smp - 4.4.0-133.159
• linux-image-4.4.0-133-powerpc64-emb - 4.4.0-133.159
• linux-image-4.4.0-133-powerpc64-smp - 4.4.0-133.159

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

• CVE-2018-3620
• CVE-2018-3646
• CVE-2018-5390
• CVE-2018-5391
• https://wiki.ubuntu.com/SecurityTeam/KnowledgeBase/L1TF

Related notices

• USN-3742-1: linux-image-3.13.0-155-powerpc64-smp, linux-image-3.13.0-155-powerpc-smp, linux, linux-image-3.13.0-155-powerpc-e500, linux-image-3.13.0-155-lowlatency, linux-image-3.13.0-155-powerpc-e500mc, linux-image-3.13.0-155-powerpc64-emb, linux-image-extra-3.13.0-155-generic, linux-image-3.13.0-155-generic, linux-image-3.13.0-155-generic-lpae
• USN-3742-2: linux-image-generic-lpae-lts-trusty, linux-image-3.13.0-155-generic, linux-lts-trusty, linux-image-generic-lts-trusty, linux-image-3.13.0-155-generic-lpae
• USN-3823-1: linux-image-3.2.0-137-generic-pae, linux-image-3.2.0-137-powerpc64-smp, linux-image-3.2.0-137-virtual, linux-image-powerpc64-smp, linux-image-virtual, linux-image-3.2.0-137-powerpc-smp, linux, linux-image-powerpc-smp, linux-image-generic, linux-image-3.2.0-137-omap, linux-image-3.2.0-137-generic, linux-image-powerpc, linux-image-highbank, linux-image-omap, linux-image-3.2.0-137-highbank, linux-image-generic-pae
• USN-3741-2: linux-image-4.4.0-133-powerpc64-emb, linux-image-4.4.0-133-generic-lpae, linux-image-4.4.0-133-generic, linux-image-4.4.0-133-powerpc64-smp, linux-image-4.4.0-133-powerpc-smp, linux-image-extra-4.4.0-133-generic, linux-aws, linux-image-4.4.0-133-lowlatency, linux-lts-xenial, linux-image-4.4.0-133-powerpc-e500mc, linux-image-4.4.0-1027-aws
• USN-3740-2: linux-image-unsigned-4.15.0-32-generic, linux-hwe, linux-gcp, linux-azure, linux-image-4.15.0-32-generic-lpae, linux-image-4.15.0-32-lowlatency, linux-image-unsigned-4.15.0-1021-azure, linux-image-unsigned-4.15.0-32-lowlatency, linux-image-4.15.0-1017-gcp, linux-image-4.15.0-32-generic
• USN-3740-1: linux, linux-image-unsigned-4.15.0-1021-azure, linux-image-4.15.0-32-lowlatency, linux-image-4.15.0-1017-gcp, linux-raspi2, linux-image-unsigned-4.15.0-1015-oem, linux-azure, linux-image-4.15.0-1019-aws, linux-image-unsigned-4.15.0-32-generic, linux-gcp, linux-image-4.15.0-1020-raspi2, linux-image-4.15.0-32-snapdragon, linux-image-4.15.0-1019-kvm, linux-kvm, linux-image-4.15.0-32-generic-lpae, linux-aws, linux-image-unsigned-4.15.0-32-lowlatency, linux-image-4.15.0-32-generic, linux-oem
• USN-3756-1: intel-microcode
• USN-3763-1: linux-image-3.2.0-135-generic-pae, linux-image-3.2.0-135-omap, linux-image-powerpc64-smp, linux-image-virtual, linux-image-3.2.0-135-virtual, linux, linux-image-3.2.0-135-powerpc64-smp, linux-image-3.2.0-135-generic, linux-image-powerpc-smp, linux-image-generic, linux-image-3.2.0-135-highbank, linux-image-3.2.0-135-powerpc-smp, linux-image-highbank, linux-image-omap, linux-image-generic-pae
• USN-3732-1: linux, linux-image-4.15.0-1017-kvm, linux-raspi2, linux-image-unsigned-4.15.0-1013-oem, linux-image-4.15.0-1017-aws, linux-azure, linux-image-unsigned-4.15.0-30-lowlatency, linux-image-4.15.0-30-lowlatency, linux-image-unsigned-4.15.0-30-generic, linux-image-unsigned-4.15.0-1019-azure, linux-image-4.15.0-1015-gcp, linux-gcp, linux-image-4.15.0-30-snapdragon, linux-kvm, linux-aws, linux-image-4.15.0-30-generic, linux-image-4.15.0-1018-raspi2, linux-oem, linux-image-4.15.0-30-generic-lpae
• USN-3732-2: linux-image-4.15.0-1015-gcp, linux-hwe, linux-gcp, linux-azure, linux-image-unsigned-4.15.0-30-lowlatency, linux-image-4.15.0-30-generic, linux-image-4.15.0-30-lowlatency, linux-image-4.15.0-30-generic-lpae, linux-image-unsigned-4.15.0-30-generic, linux-image-unsigned-4.15.0-1019-azure