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AUSCERT External Security Bulletin Redistribution
ESB-2021.3070
LSN-0081-1: Kernel Live Patch Security Notice
14 September 2021
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AusCERT Security Bulletin Summary
---------------------------------
Product: Linux Kernel
Publisher: Ubuntu
Operating System: Ubuntu
Impact/Access: Root Compromise -- Existing Account
Execute Arbitrary Code/Commands -- Existing Account
Denial of Service -- Existing Account
Access Confidential Data -- Existing Account
Reduced Security -- Existing Account
Resolution: Patch/Upgrade
CVE Names: CVE-2021-33909 CVE-2021-22555 CVE-2021-3656
CVE-2021-3653
Reference: ESB-2021.3015
ESB-2021.2899
ESB-2021.2749
Original Bulletin:
https://ubuntu.com/security/notices/LSN-0081-1
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LSN-0081-1: Kernel Live Patch Security Notice
13 September 2021
Several security issues were fixed in the kernel.
Releases
o Ubuntu 20.04 LTS
o Ubuntu 18.04 LTS
o Ubuntu 16.04 ESM
o Ubuntu 14.04 ESM
Software Description
o gcp - Linux kernel for Google Cloud Platform (GCP) systems - (>=
5.4.0-1009)
o generic-4.15 - Linux hardware enablement (HWE) kernel - (>= 4.15.0-69, >=
4.15.0-69)
o generic-4.4 - Linux kernel - (>= 4.4.0-168, >= 4.4.0-211, >= 4.4.0-168)
o generic-5.4 - Linux kernel - (>= 5.4.0-26, >= 5.4.0-26)
o gke - Linux kernel for Google Container Engine (GKE) systems - (>=
5.4.0-1033)
o gke-4.15 - Linux kernel for Google Container Engine (GKE) systems - (>=
4.15.0-1076)
o gke-5.4 - Linux kernel for Google Container Engine (GKE) systems - (>=
5.4.0-1009)
o gkeop - Linux kernel for Google Container Engine (GKE) systems - (>=
5.4.0-1009)
o gkeop-5.4 - Linux kernel for Google Container Engine (GKE) systems - (>=
5.4.0-1007)
o lowlatency-4.15 - Linux hardware enablement (HWE) kernel - (>= 4.15.0-69, >
= 4.15.0-69)
o lowlatency-4.4 - Linux kernel - (>= 4.4.0-168, >= 4.4.0-211, >= 4.4.0-168)
o lowlatency-5.4 - Linux kernel - (>= 5.4.0-26, >= 5.4.0-26)
o oem - Linux kernel for OEM systems - (>= 4.15.0-1063)
Details
Maxim Levitsky discovered that the KVM hypervisor implementation for AMD
processors in the Linux kernel did not properly prevent a guest VM from
enabling AVIC in nested guest VMs. An attacker in a guest VM could use this
to write to portions of the host's physical memory.( CVE-2021-3653 )
Maxim Levitsky and Paolo Bonzini discovered that the KVM hypervisor
implementation for AMD processors in the Linux kernel allowed a guest VM to
disable restrictions on VMLOAD/VMSAVE in a nested guest. An attacker in a
guest VM could use this to read or write portions of the host's physical
memory.( CVE-2021-3656 )
Andy Nguyen discovered that the netfilter subsystem in the Linux kernel
contained an out-of-bounds write in its setsockopt() implementation. A
local attacker could use this to cause a denial of service (system crash)
or possibly execute arbitrary code.( CVE-2021-22555 )
It was discovered that the virtual file system implementation in the Linux
kernel contained an unsigned to signed integer conversion error. A local
attacker could use this to cause a denial of service (system crash) or
execute arbitrary code.( CVE-2021-33909 )
Checking update status
The problem can be corrected in these Livepatch versions:
Kernel type 20.04 18.04 16.04 14.04
gcp 81.1 - - -
generic-4.15 - 81.1 81.1 -
generic-4.4 - - 81.1 81.1
generic-5.4 81.1 81.1 - -
gke 81.1 - - -
gke-4.15 - 81.1 - -
gke-5.4 - 81.1 - -
gkeop 81.1 - - -
gkeop-5.4 - 81.1 - -
lowlatency-4.15 - 81.1 81.1 -
lowlatency-4.4 - - 81.1 81.1
lowlatency-5.4 81.1 81.1 - -
oem - 81.1 - -
To check your kernel type and Livepatch version, enter this command:
canonical-livepatch status
References
o CVE-2021-3653
o CVE-2021-22555
o CVE-2021-3656
o CVE-2021-33909
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