USN-3835-1: Linux kernel vulnerabilities

Releases

• Ubuntu 18.10

Packages

• linux - Linux kernel
• linux-gcp - Linux kernel for Google Cloud Platform (GCP) systems
• linux-kvm - Linux kernel for cloud environments
• linux-raspi2 - Linux kernel for Raspberry Pi 2

Details

Jann Horn discovered that the procfs file system implementation in the
Linux kernel did not properly restrict the ability to inspect the kernel
stack of an arbitrary task. A local attacker could use this to expose
sensitive information. (CVE-2018-17972)

Jann Horn discovered that the mremap() system call in the Linux kernel did
not properly flush the TLB when completing, potentially leaving access to a
physical page after it has been released to the page allocator. A local
attacker could use this to cause a denial of service (system crash), expose
sensitive information, or possibly execute arbitrary code. (CVE-2018-18281)

It was discovered that the BPF verifier in the Linux kernel did not
correctly compute numeric bounds in some situations. A local attacker could
use this to cause a denial of service (system crash) or possibly execute
arbitrary code. (CVE-2018-18445)

Daniel Dadap discovered that the module loading implementation in the Linux
kernel did not properly enforce signed module loading when booted with UEFI
Secure Boot in some situations. A local privileged attacker could use this
to execute untrusted code in the kernel. (CVE-2018-18653)

Jann Horn discovered that the Linux kernel mishandles mapping UID or GID
ranges inside nested user namespaces in some situations. A local attacker
could use this to bypass access controls on resources outside the
namespace. (CVE-2018-18955)

Philipp Wendler discovered that the overlayfs implementation in the Linux
kernel did not properly verify the directory contents permissions from
within a unprivileged user namespace. A local attacker could use this to
expose sensitive information (protected file names). (CVE-2018-6559)

Update instructions

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

Ubuntu 18.10

• linux-image-gke - 4.18.0.1004.4
• linux-image-generic - 4.18.0.12.13
• linux-image-4.18.0-12-generic - 4.18.0-12.13
• linux-image-4.18.0-12-snapdragon - 4.18.0-12.13
• linux-image-4.18.0-1007-raspi2 - 4.18.0-1007.9
• linux-image-gcp - 4.18.0.1004.4
• linux-image-4.18.0-12-generic-lpae - 4.18.0-12.13
• linux-image-4.18.0-1004-gcp - 4.18.0-1004.5
• linux-image-4.18.0-12-lowlatency - 4.18.0-12.13
• linux-image-generic-lpae - 4.18.0.12.13
• linux-image-4.18.0-1005-kvm - 4.18.0-1005.5
• linux-image-snapdragon - 4.18.0.12.13
• linux-image-kvm - 4.18.0.1005.5
• linux-image-lowlatency - 4.18.0.12.13
• linux-image-raspi2 - 4.18.0.1007.4

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-2018-17972
• CVE-2018-18281
• CVE-2018-18445
• CVE-2018-18653
• CVE-2018-18955
• CVE-2018-6559

Related notices

• USN-3821-1: linux, linux-raspi2, linux-image-4.4.0-139-generic-lpae, linux-kvm, linux-image-4.4.0-1100-raspi2, linux-image-4.4.0-139-powerpc64-emb, linux-aws, linux-image-extra-4.4.0-139-generic, linux-image-4.4.0-1104-snapdragon, linux-image-4.4.0-139-powerpc-e500mc, linux-image-4.4.0-139-generic, linux-image-4.4.0-139-powerpc-smp, linux-snapdragon, linux-image-4.4.0-139-powerpc64-smp, linux-image-4.4.0-1072-aws, linux-image-4.4.0-1037-kvm, linux-image-4.4.0-139-lowlatency
• USN-3880-2: linux-lts-trusty, linux-image-generic-lts-trusty, linux-image-3.13.0-165-generic-lpae, linux-image-generic-lpae-lts-trusty, linux-image-3.13.0-165-generic
• USN-3871-4: linux-aws-hwe, linux-gcp, linux-image-4.15.0-1027-gcp, linux-hwe, linux-image-aws-hwe, linux-image-4.15.0-1032-aws, linux-image-gke, linux-image-virtual-hwe-16.04, linux-image-oem, linux-image-generic-lpae-hwe-16.04, linux-image-generic-hwe-16.04, linux-image-lowlatency-hwe-16.04, linux-image-4.15.0-45-generic, linux-image-gcp, linux-image-4.15.0-45-generic-lpae, linux-image-4.15.0-45-lowlatency
• USN-3871-1: linux-image-generic-hwe-16.04-edge, linux-image-generic-lpae-hwe-16.04-edge, linux, linux-image-virtual-hwe-16.04, linux-image-4.15.0-44-snapdragon, linux-image-4.15.0-44-lowlatency, linux-image-generic-lpae-hwe-16.04, linux-image-virtual-hwe-16.04-edge, linux-image-4.15.0-44-generic, linux-image-generic-hwe-16.04, linux-image-4.15.0-44-generic-lpae, linux-image-generic, linux-image-generic-lpae, linux-image-lowlatency-hwe-16.04, linux-image-lowlatency-hwe-16.04-edge, linux-image-virtual, linux-image-snapdragon, linux-image-lowlatency
• USN-3871-5: linux-image-azure, linux-azure, linux-image-4.15.0-1037-azure
• USN-3832-1: linux-image-aws, linux-image-4.18.0-1006-aws, linux-aws
• USN-3880-1: linux-image-lowlatency-pae, linux-image-3.13.0-165-powerpc-e500mc, linux-image-generic-lts-raring, linux-image-3.13.0-165-generic, linux-image-powerpc64-emb, linux-image-3.13.0-165-powerpc64-emb, linux, linux-image-highbank, linux-image-powerpc-e500mc, linux-image-powerpc64-smp, linux-image-powerpc-e500, linux-image-3.13.0-165-powerpc-smp, linux-image-powerpc-smp, linux-image-generic-pae, linux-image-lowlatency, linux-image-generic-lts-saucy, linux-image-3.13.0-165-powerpc-e500, linux-image-generic, linux-image-generic-lpae, linux-image-3.13.0-165-lowlatency, linux-image-virtual, linux-image-3.13.0-165-powerpc64-smp, linux-image-omap, linux-image-generic-lts-quantal, linux-image-generic-lts-trusty, linux-image-3.13.0-165-generic-lpae, linux-image-generic-lpae-lts-trusty, linux-image-generic-lpae-lts-saucy
• USN-3871-3: linux-image-gke, linux-gcp, linux-image-4.15.0-1027-gcp, linux-image-4.15.0-1029-kvm, linux-image-4.15.0-1032-aws, linux-image-4.15.0-1033-oem, linux-image-oem, linux-image-4.15.0-1031-raspi2, linux-kvm, linux-oem, linux-image-gcp, linux-image-raspi2, linux-image-aws, linux-image-kvm, linux-aws, linux-raspi2
• USN-3821-2: linux-lts-xenial, linux-image-4.4.0-139-powerpc64-emb, linux-image-4.4.0-1034-aws, linux-aws, linux-image-extra-4.4.0-139-generic, linux-image-4.4.0-139-powerpc-e500mc, linux-image-4.4.0-139-generic, linux-image-4.4.0-139-powerpc-smp, linux-image-4.4.0-139-powerpc64-smp, linux-image-4.4.0-139-generic-lpae, linux-image-4.4.0-139-lowlatency
• USN-3847-2: linux-aws-hwe, linux-gcp, linux-image-unsigned-4.15.0-1026-gcp, linux-hwe, linux-image-4.15.0-43-lowlatency, linux-image-unsigned-4.15.0-1036-azure, linux-azure, linux-image-unsigned-4.15.0-43-lowlatency, linux-image-4.15.0-43-generic-lpae, linux-image-4.15.0-43-generic, linux-image-unsigned-4.15.0-43-generic, linux-image-4.15.0-1031-aws
• USN-3847-3: linux-image-unsigned-4.15.0-1036-azure, linux-azure
• USN-3847-1: linux-image-unsigned-4.15.0-1026-gcp, linux-image-4.15.0-43-lowlatency, linux-kvm, linux-image-unsigned-4.15.0-43-lowlatency, linux-image-unsigned-4.15.0-1030-oem, linux-image-4.15.0-1030-raspi2, linux-gcp, linux, linux-aws, linux-image-4.15.0-1028-kvm, linux-image-4.15.0-43-generic, linux-image-unsigned-4.15.0-43-generic, linux-image-4.15.0-1031-aws, linux-raspi2, linux-image-unsigned-4.15.0-1036-azure, linux-image-4.15.0-43-snapdragon, linux-azure, linux-oem, linux-image-4.15.0-43-generic-lpae
• USN-3833-1: linux-image-4.15.0-1029-aws, linux-aws
• USN-3836-1: linux-image-4.15.0-1027-kvm, linux-gcp, linux, linux-image-4.15.0-42-lowlatency, linux-image-4.15.0-42-snapdragon, linux-kvm, linux-image-4.15.0-42-generic, linux-image-4.15.0-42-generic-lpae, linux-image-unsigned-4.15.0-42-generic, linux-image-unsigned-4.15.0-42-lowlatency, linux-image-unsigned-4.15.0-1025-gcp, linux-image-4.15.0-1029-raspi2, linux-raspi2
• USN-3836-2: linux-gcp, linux-hwe, linux-image-4.15.0-42-lowlatency, linux-image-4.15.0-42-generic, linux-image-4.15.0-42-generic-lpae, linux-image-unsigned-4.15.0-42-generic, linux-image-unsigned-4.15.0-42-lowlatency, linux-image-unsigned-4.15.0-1025-gcp