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CVE-2019-14821

Published: 1 October 2019

An out-of-bounds access issue was found in the Linux kernel, all versions through 5.3, in the way Linux kernel's KVM hypervisor implements the Coalesced MMIO write operation. It operates on an MMIO ring buffer 'struct kvm_coalesced_mmio' object, wherein write indices 'ring->first' and 'ring->last' value could be supplied by a host user-space process. An unprivileged host user or process with access to '/dev/kvm' device could use this flaw to crash the host kernel, resulting in a denial of service or potentially escalating privileges on the system.

From the Ubuntu security team

Matt Delco discovered that the KVM hypervisor implementation in the Linux kernel did not properly perform bounds checking when handling coalesced MMIO write operations. A local attacker with write access to /dev/kvm could use this to cause a denial of service (system crash).

Notes

AuthorNote
tyhicks
An attacker needs write access to the /dev/kvm device file to exploit
this flaw. By default, Ubuntu users don't have privileges to write to
/dev/kvm. This is true even when libvirt is installed and in use.

Mitigation

Ensure that untrusted users cannot write to the /dev/kvm device
Priority

Medium

CVSS 3 base score: 8.8

Status

Package Release Status
linux
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-66.75)
disco
Released (5.0.0-32.34)
eoan Not vulnerable
(5.3.0-17.18)
focal Not vulnerable
(5.4.0-9.12)
precise Ignored
(was needed ESM criteria)
trusty Ignored
(was needed ESM criteria)
upstream
Released (5.4~rc1)
xenial
Released (4.4.0-166.195)
Patches:
Introduced by

5f94c1741bdc7a336553122036e8a779e616ccbf

Fixed by b60fe990c6b07ef6d4df67bc0530c7c90a62623a
linux-aws
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1052.54)
disco
Released (5.0.0-1019.21)
eoan Not vulnerable
(5.3.0-1003.3)
focal Not vulnerable
(5.4.0-1005.5)
precise Does not exist

trusty
Released (4.4.0-1056.60)
upstream
Released (5.4~rc1)
xenial
Released (4.4.0-1096.107)
linux-aws-5.0
Launchpad, Ubuntu, Debian
bionic Not vulnerable
(5.0.0-1021.24~18.04.1)
disco Does not exist

eoan Does not exist

focal Does not exist

precise Does not exist

trusty Does not exist

upstream
Released (5.4~rc1)
xenial Does not exist

linux-aws-hwe
Launchpad, Ubuntu, Debian
bionic Does not exist

disco Does not exist

eoan Does not exist

focal Does not exist

precise Does not exist

trusty Does not exist

upstream
Released (5.4~rc1)
xenial
Released (4.15.0-1052.54~16.04.1)
linux-azure
Launchpad, Ubuntu, Debian
bionic
Released (5.0.0-1023.24~18.04.1)
disco
Released (5.0.0-1023.24)
eoan Not vulnerable
(5.3.0-1002.2)
focal Not vulnerable
(5.4.0-1006.6)
precise Does not exist

trusty
Released (4.15.0-1061.66~14.04.1)
upstream
Released (5.4~rc1)
xenial
Released (4.15.0-1061.66)
linux-azure-5.3
Launchpad, Ubuntu, Debian
bionic Not vulnerable
(5.3.0-1007.8~18.04.1)
disco Does not exist

eoan Does not exist

focal Does not exist

precise Does not exist

trusty Does not exist

upstream
Released (5.4~rc1)
xenial Does not exist

linux-azure-edge
Launchpad, Ubuntu, Debian
bionic
Released (5.0.0-1023.24~18.04.1)
disco Does not exist

eoan Does not exist

focal Does not exist

precise Does not exist

trusty Does not exist

upstream
Released (5.4~rc1)
xenial
Released (4.15.0-1061.66)
linux-gcp
Launchpad, Ubuntu, Debian
bionic
Released (5.0.0-1021.21~18.04.1)
disco
Released (5.0.0-1021.21)
eoan Not vulnerable
(5.3.0-1003.3)
focal Not vulnerable
(5.4.0-1005.5)
precise Does not exist

trusty Does not exist

upstream
Released (5.4~rc1)
xenial
Released (4.15.0-1047.50)
linux-gcp-5.3
Launchpad, Ubuntu, Debian
bionic Not vulnerable
(5.3.0-1008.9~18.04.1)
disco Does not exist

eoan Does not exist

focal Does not exist

precise Does not exist

trusty Does not exist

upstream
Released (5.4~rc1)
xenial Does not exist

linux-gcp-edge
Launchpad, Ubuntu, Debian
bionic
Released (5.0.0-1021.21~18.04.1)
disco Does not exist

eoan Does not exist

focal Does not exist

precise Does not exist

trusty Does not exist

upstream
Released (5.4~rc1)
xenial Does not exist

linux-gke-4.15
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1046.49)
disco Does not exist

eoan Does not exist

focal Does not exist

precise Does not exist

trusty Does not exist

upstream
Released (5.4~rc1)
xenial Does not exist

linux-gke-5.0
Launchpad, Ubuntu, Debian
bionic
Released (5.0.0-1023.23~18.04.2)
disco Does not exist

eoan Does not exist

focal Does not exist

precise Does not exist

trusty Does not exist

upstream
Released (5.4~rc1)
xenial Does not exist

linux-gke-5.3
Launchpad, Ubuntu, Debian
bionic Not vulnerable
(5.3.0-1011.12~18.04.1)
eoan Does not exist

focal Does not exist

precise Does not exist

trusty Does not exist

upstream
Released (5.4~rc1)
xenial Does not exist

linux-hwe
Launchpad, Ubuntu, Debian
bionic
Released (5.0.0-32.34~18.04.2)
disco Does not exist

eoan Does not exist

focal Does not exist

precise Does not exist

trusty Does not exist

upstream
Released (5.4~rc1)
xenial
Released (4.15.0-66.75~16.04.1)
linux-hwe-edge
Launchpad, Ubuntu, Debian
bionic Ignored
(was pending \[5.3.0-19.20~18.04.2\] now end-of-life)
disco Does not exist

eoan Does not exist

focal Does not exist

precise Does not exist

trusty Does not exist

upstream
Released (5.4~rc1)
xenial
Released (4.15.0-66.75~16.04.1)
linux-kvm
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1048.48)
disco
Released (5.0.0-1020.21)
eoan Not vulnerable
(5.3.0-1003.3)
focal Not vulnerable
(5.4.0-1004.4)
precise Does not exist

trusty Does not exist

upstream
Released (5.4~rc1)
xenial
Released (4.4.0-1060.67)
linux-lts-trusty
Launchpad, Ubuntu, Debian
bionic Does not exist

disco Does not exist

eoan Does not exist

focal Does not exist

precise Ignored
(was needed ESM criteria)
trusty Does not exist

upstream
Released (5.4~rc1)
xenial Does not exist

linux-lts-xenial
Launchpad, Ubuntu, Debian
bionic Does not exist

disco Does not exist

eoan Does not exist

focal Does not exist

precise Does not exist

trusty
Released (4.4.0-166.195~14.04.1)
upstream
Released (5.4~rc1)
xenial Does not exist

linux-oem
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1059.68)
disco Ignored
(reached end-of-life)
eoan
Released (4.15.0-1059.68)
focal Does not exist

precise Does not exist

trusty Does not exist

upstream
Released (5.4~rc1)
xenial Ignored
(was needs-triage now end-of-life)
linux-oem-5.6
Launchpad, Ubuntu, Debian
bionic Does not exist

eoan Does not exist

focal Not vulnerable
(5.4.0-1002.4)
precise Does not exist

trusty Does not exist

upstream
Released (5.4~rc1)
xenial Does not exist

linux-oem-osp1
Launchpad, Ubuntu, Debian
bionic
Released (5.0.0-1025.28)
disco Ignored
(reached end-of-life)
eoan
Released (5.0.0-1025.28)
focal Does not exist

precise Does not exist

trusty Does not exist

upstream
Released (5.4~rc1)
xenial Does not exist

linux-oracle
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1027.30)
disco Ignored
(was pending \[5.0.0-1005.9\] now end-of-life)
eoan Not vulnerable
(5.3.0-1002.2)
focal Not vulnerable
(5.4.0-1005.5)
precise Does not exist

trusty Does not exist

upstream
Released (5.4~rc1)
xenial
Released (4.15.0-1027.30~16.04.1)
linux-oracle-5.0
Launchpad, Ubuntu, Debian
bionic Not vulnerable
(5.0.0-1007.12~18.04.1)
disco Does not exist

eoan Does not exist

focal Does not exist

precise Does not exist

trusty Does not exist

upstream
Released (5.4~rc1)
xenial Does not exist

linux-oracle-5.3
Launchpad, Ubuntu, Debian
bionic Not vulnerable
(5.3.0-1011.12~18.04.1)
eoan Does not exist

focal Does not exist

precise Does not exist

trusty Does not exist

upstream
Released (5.4~rc1)
xenial Does not exist

linux-raspi2
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1049.53)
disco
Released (5.0.0-1020.20)
eoan Not vulnerable
(5.3.0-1006.7)
focal Not vulnerable
(5.4.0-1004.4)
precise Does not exist

trusty Does not exist

upstream
Released (5.4~rc1)
xenial
Released (4.4.0-1124.133)
linux-raspi2-5.3
Launchpad, Ubuntu, Debian
bionic Not vulnerable
(5.3.0-1017.19~18.04.1)
eoan Does not exist

focal Does not exist

precise Does not exist

trusty Does not exist

upstream
Released (5.4~rc1)
xenial Does not exist

linux-snapdragon
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1066.73)
disco
Released (5.0.0-1024.25)
eoan Does not exist

focal Does not exist

precise Does not exist

trusty Does not exist

upstream
Released (5.4~rc1)
xenial
Released (4.4.0-1128.136)