USN-4318-1: Linux kernel vulnerabilities

Releases

• Ubuntu 18.04 ESM
• Ubuntu 16.04 ESM

Packages

• linux - Linux kernel
• linux-hwe - Linux hardware enablement (HWE) kernel

Details

Al Viro discovered that the vfs layer in the Linux kernel contained a use-
after-free vulnerability. A local attacker could use this to cause a denial
of service (system crash) or possibly expose sensitive information (kernel
memory). (CVE-2020-8428)

Gustavo Romero and Paul Mackerras discovered that the KVM implementation in
the Linux kernel for PowerPC processors did not properly keep guest state
separate from host state. A local attacker in a KVM guest could use this to
cause a denial of service (host system crash). (CVE-2020-8834)

Shijie Luo discovered that the ext4 file system implementation in the Linux
kernel did not properly check for a too-large journal size. An attacker
could use this to construct a malicious ext4 image that, when mounted,
could cause a denial of service (soft lockup). (CVE-2020-8992)

Update instructions

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

Ubuntu 18.04

• linux-image-4.15.0-96-generic - 4.15.0-96.97
• linux-image-4.15.0-96-generic-lpae - 4.15.0-96.97
• linux-image-4.15.0-96-lowlatency - 4.15.0-96.97
• linux-image-generic - 4.15.0.96.87
• linux-image-generic-lpae - 4.15.0.96.87
• linux-image-lowlatency - 4.15.0.96.87
• linux-image-virtual - 4.15.0.96.87

Ubuntu 16.04

• linux-image-4.15.0-96-generic - 4.15.0-96.97~16.04.1
• linux-image-4.15.0-96-generic-lpae - 4.15.0-96.97~16.04.1
• linux-image-4.15.0-96-lowlatency - 4.15.0-96.97~16.04.1
• linux-image-generic-hwe-16.04 - 4.15.0.96.104
• linux-image-generic-lpae-hwe-16.04 - 4.15.0.96.104
• linux-image-lowlatency-hwe-16.04 - 4.15.0.96.104
• linux-image-oem - 4.15.0.96.104
• linux-image-virtual-hwe-16.04 - 4.15.0.96.104

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-2020-8428
• CVE-2020-8834
• CVE-2020-8992

Related notices

• USN-4320-1: linux-image-powerpc64-smp-lts-xenial, linux-image-powerpc64-emb-lts-wily, linux-image-powerpc64-emb, linux-image-generic-lpae-lts-xenial, linux-image-powerpc64-smp-lts-wily, linux-image-powerpc64-smp-lts-utopic, linux-kvm, linux-image-4.4.0-177-generic, linux-image-powerpc-e500mc, linux-snapdragon, linux-image-generic-lpae, linux-image-powerpc64-smp, linux-image-powerpc64-emb-lts-utopic, linux-image-generic-lts-vivid, linux-image-virtual, linux-image-generic-lpae-lts-utopic, linux-image-4.4.0-177-powerpc64-emb, linux-image-snapdragon, linux-image-powerpc64-emb-lts-vivid, linux-image-virtual-lts-xenial, linux-image-generic-lts-xenial, linux-image-4.4.0-177-powerpc-e500mc, linux-image-4.4.0-177-lowlatency, linux-image-aws, linux-image-4.4.0-177-powerpc64-smp, linux-image-generic-lpae-lts-vivid, linux-image-lowlatency-lts-wily, linux-image-generic-lpae-lts-wily, linux-image-powerpc-e500mc-lts-xenial, linux-image-raspi2, linux-image-virtual-lts-utopic, linux-image-kvm, linux-image-4.4.0-1131-raspi2, linux-image-lowlatency-lts-vivid, linux-image-powerpc-smp-lts-vivid, linux-raspi2, linux-image-4.4.0-1065-aws, linux-image-generic-lts-utopic, linux-image-virtual-lts-vivid, linux-image-generic-lts-wily, linux-image-powerpc64-emb-lts-xenial, linux-image-powerpc-smp, linux-image-lowlatency, linux, linux-image-4.4.0-1135-snapdragon, linux-image-powerpc-e500mc-lts-vivid, linux-image-powerpc64-smp-lts-vivid, linux-image-powerpc-smp-lts-xenial, linux-image-lowlatency-lts-xenial, linux-image-4.4.0-1105-aws, linux-image-virtual-lts-wily, linux-image-powerpc-e500mc-lts-utopic, linux-image-powerpc-smp-lts-utopic, linux-lts-xenial, linux-image-powerpc-smp-lts-wily, linux-image-4.4.0-177-powerpc-smp, linux-image-generic, linux-image-lowlatency-lts-utopic, linux-image-powerpc-e500mc-lts-wily, linux-image-4.4.0-1069-kvm, linux-image-4.4.0-177-generic-lpae, linux-aws
• USN-4319-1: linux-image-azure, linux-kvm, linux-image-virtual-hwe-18.04-edge, linux-image-generic-hwe-18.04, linux-image-5.3.0-1015-kvm, linux-image-5.3.0-46-snapdragon, linux-image-gcp, linux-image-generic-lpae, linux-image-virtual, linux-image-5.3.0-46-generic-lpae, linux-image-5.3.0-1016-aws, linux-image-snapdragon, linux-image-oracle, linux-image-5.3.0-46-generic, linux-azure-5.3, linux-image-5.3.0-1017-gcp, linux-image-gke, linux-image-snapdragon-hwe-18.04-edge, linux-image-aws, linux-image-5.3.0-1019-azure, linux-image-generic-hwe-18.04-edge, linux-image-raspi2, linux-image-generic-lpae-hwe-18.04-edge, linux-image-kvm, linux-gcp, linux-raspi2, linux-hwe, linux-oracle-5.3, linux-oracle, linux-image-raspi2-hwe-18.04, linux-image-generic-lpae-hwe-18.04, linux-image-lowlatency, linux-raspi2-5.3, linux, linux-azure, linux-image-5.3.0-1022-raspi2, linux-image-gcp-edge, linux-image-5.3.0-46-lowlatency, linux-image-5.3.0-1014-oracle, linux-image-lowlatency-hwe-18.04, linux-image-virtual-hwe-18.04, linux-gcp-5.3, linux-image-snapdragon-hwe-18.04, linux-image-lowlatency-hwe-18.04-edge, linux-image-generic, linux-image-oracle-edge, linux-image-azure-edge, linux-aws
• USN-4324-1: linux-image-azure, linux-image-4.15.0-1077-azure, linux-kvm, linux-snapdragon, linux-image-4.15.0-1065-aws, linux-image-gcp, linux-image-snapdragon, linux-image-oracle, linux-image-gke, linux-image-4.15.0-1060-raspi2, linux-image-4.15.0-1076-snapdragon, linux-image-gke-4.15, linux-gke-4.15, linux-image-aws, linux-image-raspi2, linux-image-kvm, linux-gcp, linux-image-oracle-lts-18.04, linux-raspi2, linux-oracle, linux-oem, linux-image-4.15.0-1037-oracle, linux-image-aws-lts-18.04, linux-azure, linux-image-4.15.0-1057-gke, linux-image-4.15.0-1058-kvm, linux-image-4.15.0-1060-gcp, linux-aws-hwe, linux-image-4.15.0-1079-oem, linux-image-aws-hwe, linux-image-oem, linux-image-azure-edge, linux-aws
• USN-4325-1: linux-image-azure, linux-image-gke-5.0, linux-image-oracle, linux-gcp, linux-image-5.0.0-1036-azure, linux-oracle-5.0, linux-image-5.0.0-1014-oracle, linux-image-5.0.0-1047-oem-osp1, linux-image-gcp, linux-image-5.0.0-1034-gcp, linux-image-oem-osp1, linux-oem-osp1, linux-azure, linux-image-5.0.0-1033-gke, linux-gke-5.0
• LSN-0065-1: generic-4.15, gcp, generic-4.4, lowlatency-4.15, aws, lowlatency-4.4, azure
• USN-4344-1: linux-oem-osp1, linux-image-oem-osp1, linux-image-5.0.0-1035-gke, linux-image-5.0.0-1050-oem-osp1, linux-image-gke-5.0, linux-gke-5.0
• USN-4342-1: linux-image-azure, linux-image-5.3.0-1023-raspi2, linux-image-5.3.0-1018-gcp, linux-image-5.3.0-1017-aws, linux-kvm, linux-image-virtual-hwe-18.04-edge, linux-image-5.3.0-1020-azure, linux-image-5.3.0-51-snapdragon, linux-image-generic-hwe-18.04, linux-image-gcp, linux-image-generic-lpae, linux-image-virtual, linux-image-snapdragon, linux-image-oracle, linux-azure-5.3, linux-image-5.3.0-1016-kvm, linux-image-gke, linux-image-snapdragon-hwe-18.04-edge, linux-image-aws, linux-gke-5.3, linux-image-generic-hwe-18.04-edge, linux-image-raspi2, linux-image-generic-lpae-hwe-18.04-edge, linux-image-gke-5.3, linux-image-kvm, linux-gcp, linux-raspi2, linux-hwe, linux-image-5.3.0-1018-gke, linux-oracle-5.3, linux-oracle, linux-image-raspi2-hwe-18.04, linux-image-generic-lpae-hwe-18.04, linux-image-lowlatency, linux-raspi2-5.3, linux, linux-azure, linux-image-gcp-edge, linux-image-5.3.0-51-lowlatency, linux-image-lowlatency-hwe-18.04, linux-gcp-5.3, linux-image-snapdragon-hwe-18.04, linux-image-virtual-hwe-18.04, linux-image-lowlatency-hwe-18.04-edge, linux-image-5.3.0-1016-oracle, linux-image-generic, linux-image-oracle-edge, linux-image-5.3.0-51-generic-lpae, linux-image-5.3.0-51-generic, linux-image-azure-edge, linux-aws
• USN-4419-1: linux-image-powerpc64-smp-lts-xenial, linux-image-powerpc64-emb-lts-wily, linux-image-powerpc64-emb, linux-image-generic-lpae-lts-xenial, linux-image-powerpc64-smp-lts-wily, linux-image-powerpc64-smp-lts-utopic, linux-image-4.4.0-1110-aws, linux-kvm, linux-image-powerpc-e500mc, linux-image-4.4.0-185-powerpc-e500mc, linux-image-4.4.0-185-lowlatency, linux-image-4.4.0-185-powerpc64-smp, linux-snapdragon, linux-image-4.4.0-185-powerpc64-emb, linux-image-generic-lpae, linux-image-powerpc64-smp, linux-image-4.4.0-1076-kvm, linux-image-4.4.0-1074-aws, linux-image-4.4.0-185-generic-lpae, linux-image-generic-lts-vivid, linux-image-generic-lpae-lts-utopic, linux-image-4.4.0-1135-raspi2, linux-image-powerpc64-emb-lts-utopic, linux-image-4.4.0-185-generic, linux-image-powerpc64-emb-lts-vivid, linux-image-snapdragon, linux-image-virtual-lts-xenial, linux-image-4.4.0-185-powerpc-smp, linux-image-virtual, linux-image-generic-lts-xenial, linux-image-aws, linux-image-generic-lpae-lts-vivid, linux-image-lowlatency-lts-wily, linux-image-generic-lpae-lts-wily, linux-image-powerpc-e500mc-lts-xenial, linux-image-raspi2, linux-image-virtual-lts-utopic, linux-image-kvm, linux-image-4.4.0-1139-snapdragon, linux-image-lowlatency-lts-vivid, linux-image-powerpc-smp-lts-vivid, linux-raspi2, linux-image-generic-lts-utopic, linux-image-virtual-lts-vivid, linux-image-generic-lts-wily, linux-image-powerpc64-emb-lts-xenial, linux-image-powerpc-smp, linux-image-lowlatency, linux, linux-image-powerpc-e500mc-lts-vivid, linux-image-powerpc64-smp-lts-vivid, linux-image-powerpc-smp-lts-xenial, linux-image-lowlatency-lts-xenial, linux-image-virtual-lts-wily, linux-image-powerpc-e500mc-lts-utopic, linux-image-powerpc-smp-lts-utopic, linux-lts-xenial, linux-image-powerpc-smp-lts-wily, linux-image-generic, linux-image-lowlatency-lts-utopic, linux-image-powerpc-e500mc-lts-wily, linux-aws