USN-3740-1: Linux kernel vulnerabilities
14 August 2018
Several security issues were fixed in the Linux kernel.
Releases
Packages
- linux - Linux kernel
- linux-aws - Linux kernel for Amazon Web Services (AWS) systems
- linux-azure - Linux kernel for Microsoft Azure Cloud systems
- linux-gcp - Linux kernel for Google Cloud Platform (GCP) systems
- linux-kvm - Linux kernel for cloud environments
- linux-oem - Linux kernel for OEM processors
- linux-raspi2 - Linux kernel for Raspberry Pi 2
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 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 18.04
-
linux-image-4.15.0-1017-gcp
-
4.15.0-1017.18
-
linux-image-4.15.0-1019-aws
-
4.15.0-1019.19
-
linux-image-4.15.0-1019-kvm
-
4.15.0-1019.19
-
linux-image-4.15.0-1020-raspi2
-
4.15.0-1020.22
-
linux-image-4.15.0-32-generic
-
4.15.0-32.35
-
linux-image-4.15.0-32-generic-lpae
-
4.15.0-32.35
-
linux-image-4.15.0-32-lowlatency
-
4.15.0-32.35
-
linux-image-4.15.0-32-snapdragon
-
4.15.0-32.35
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.